David M Meko

Interests

Teaching

Time series analysis

Research

Climatology, hydrology, climate variability, tree rings, water supply

Courses

Scholarly Contributions

Books

• Meko, D. M., & Piovano, E. L. (2015). Advances in Paleohydrology Research and Applications, Special Issue of Journal of Hydrology, vol. 529, Part 2, pages 431– 684. Elsevier.
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  Special issue, J of Hydrology
• Dean, J. S., Meko, D. M., & Swetnam, T. W. (1996). Tree Rings, Environment and Humanity, Proceedings of the International Conference, 17-21 May, 1994. Tucson: Radiocarbon.

Chapters

• Woodhouse, C. A., Lukas, J. J., Morino, K. A., Meko, D. M., & Hirschboeck, K. K. (2016). Chapter 11: Using the past to plan for the future – The value of paleoclimate reconstructions for water resource planning. In Water Policy and Planning in a Variable and Changing Climate. https://www.crcpress.com/Water-Policy-and-Planning-in-a-Variable-Changing-Climate/Miller-Hamlet-Kenney-Redmond/9781482227970: CRC Press - Taylor and Francis.
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  Eds: Kathleen Miller, Alan Hamlet, Douglas Kenney and Kelly RedmondSeries Title & Editor: Drought and Water Crises: Science, Technology, Management, and Policy Issues for the 21st Century, Donald A. Wilhite (Series Editor)
• Meko, D. M., & Woodhouse, C. A. (2011). Application of streamflow reconstruction to water resources management,. In In Dendroclimatology, Progress and Prospects, Developments in Paleoenvironmental Research, vol. 11, edited by M. K. Hughes, T. W. Swetnam, and H. F. Diaz,(pp 231-261). Netherlands: Springer.
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  Meko, D. M., and C. A. Woodhouse (2011), Application of streamflow reconstruction to water resources management, in Dendroclimatology, Progress and Prospects, Develop- ments in Paleoenvironmental Research, vol. 11, edited by M. K. Hughes, T. W. Swetnam, and H. F. Diaz, pp. 231-261, Springer Netherlands.
• Meko, D. M. (1993). Spectral properties of tree-ring data in the United States southwest as related to El Nino/Southern Oscillation. In El Nino: historical and paleoclimatic aspects of the Southern Oscillation, Diaz, H.F., and Markgraf, V., eds.(pp 227-241). Cambridge: Cambridge University Press.
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  Abstract: The spatial extent and geographic orientation of significant interregional tree-ring correlation in the ENSO band is similar to that in the entire 0 to π frequency range. Spatial correlations with the Southwest region are highly significant (99.9% level) and in-phase in a band oriented southwest-northeast from Southern California to Colorado, and weakly significant (95% level) and in-phase with northwestern Wyoming. Spatial correlation of Southwest tree rings with other regional tree-ring series is strongest outside the ENSO band, at wavelengths 20 yr and longer. An important component of low-frequency variance in Southwest trees is a pronounced downward growth trend from the early 1900s to the 1950s. -from Author
• Meko, D. M. (1992). Dendroclimatic evidence from the Great Plains of the United States. In Climate since A.D. 1500,Bradley, R.S., and Jones, P.D., eds(pp 312-330). London: Routledge,.
• Meko, D. M., Hughes, M. K., & Stockton, C. W. (1991). Climate change and climate variability: The paleo record. In Managing Water Resources in the West under Conditions of Climate Uncertainty(pp 71-100). National Academy Press.
• Stockton, C. W., Boggess, W. R., & Meko, D. M. (1985). Climate and tree rings. In Paleoclimate analysis and modeling, Hecht, A.D., ed(pp 71-150). John Wiley & Sons.

Journals/Publications

• Winitsky, A. G., Winitsky, A. G., Meko, D. M., Meko, D. M., Taylor, A. H., Taylor, A. H., Biondi, F., & Biondi, F. (2023). Species Sensitivity to Hydrologic Whiplash in The Tree-Ring Record of the High Sierra Nevada. Environments, 10(1), 12. doi:10.3390/environments10010012
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  Winitsky, A. G., Meko, D. M., Taylor, A. H., & Biondi, F. (2023). Species sensitivity to hydrologic whiplash in the tree-ring record of the High Sierra Nevada. Environments, 10 (1), 12. (Published online 13 January 2023) doi: 10.3390/environments10010012
• Testa, N. R., Squire, J., Van de Water, P., Jull, A. J., Black, B., Meko, D. M., Leavitt, S. W., & Panyushkina, I. P. (2022). Douglas fir multiproxy tree-ring data glimpse MIS 5 environment in the U.S. Pacific Northwest. Forests, 13(12), 2161. doi:https://doi.org/10.3390/f13122161
• Belokopytova, L. V., Meko, D. M., Zhirnova, D. F., Babushkina, E. A., & Vaganov, E. A. (2021). Spatial classification of moisture-sensitive pine and larch tree-ring chronologies within Khakass-Minusinsk Depression, South Siberia.. Trees, 35(6), 2133-2139. doi:10.1007/s00468-021-02196-7
• Nolin, A. F., Tardif, J. C., Conciatori, F., Meko, D. M., & Bergeron, Y. (2021). Multi-century tree-ring anatomical evidence reveals increasing frequency and amplitude of spring discharge and flood in eastern boreal Canada. Global Change Biology, 199, 103444. doi:10.1016/j.gloplacha.2021.103444
• Touchan, R., Black, B., Shamir, E., Hughes, M. K., & Meko, D. M. (2021). A mul-timillennial snow water equivalent reconstruction from giant sequoia tree rings. Climate Dynamics, 56, 1507--1518. doi:10.1007/s00382-020-05548-0
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  Touchan, R., Black, B., Shamir, E., Hughes, M. K., & Meko, D. M. (2021). A mul- timillennial snow water equivalent reconstruction from giant sequoia tree rings. Clim. Dynam.. (Submitted September 2020) doi: 10.1007/s00382-020-05548-0 Volume="56", pages"1507--1518", doi="10.1007/s00382-020-05548-0"
• Williams, A. P., Anchukaitis, K., Woodhouse, C. A., Meko, D. M., Cook, B. I., Bolles, K., & Cook, E. R. (2021). Tree rings and observations suggest no stable cycles in Sierra Nevada cool-season precipitation. PNAS, 57, e2020WR028599. doi:10.1029/2020WR028599
• Zhirnova, D. F., Belokopytova, L. V., Meko, D. M., Babushkina, E. A., & Vaganov, E. A. (2021). Climate change and tree growth in the Khakass-Minusinsk Depression (South Siberia) impacted by large water reservoirs. Sci. Rep., 11, 14266.. doi:10.1038/s41598-021-93745
• Coulthard, B., St. George, S., & Meko, D. M. (2020). The limits of freely-available tree-ring chronologies. Quat. Sci. Rev., 234, 106264. doi:10.1016/j.quascirev.2020.106264
• Lepley, K., Touchan, R., Meko, D., Shamir, E., Graham, R., & Falk, D. (2020). A multi-century Sierra Nevada snowpack reconstruction modeled using upper-elevation coniferous tree rings. The Holocene, First published online May 12, 2020, 1-13. doi:10.1177/0959683620919972
• Meko, D. M., Touchan, R., Kherchouche, D., & Slimani, S. (2020). Direct versus indirect tree-ring reconstruction of annual discharge of Chemora River, Algeria. Forests, 11(9), 986. doi:10.3390/f11090986
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  Meko, D. M., Touchan, R., Kherchouche, D., & Slimani, S. (2020). Direct versus in- direct tree-ring reconstruction of annual discharge of Chemora River, Algeria. Forests, 11 (9), 986. doi: 10.3390/f11090986
• Shamir, E., Meko, D. M., Touchan, R., Lepley, K. S., Graham, R., Kaliff, R. N., & Georgakakos, K. P. (2019). Annual climatological indices and their association with conifers radial growth at the Sierra Nevada, California. Journal of Geophysical Research: Biogeosciences, 125(e2019JG005331), 1-21. doi:https://doi.org/ 10.1029/2019JG005331
• Chen, F., Shang, H., Panyushkina, I. P., Meko, D. M., Yu, S., Yuan, Y., & Chen, F. (2019). Tree-ring reconstruction of Lhasa River streamflow reveals 472 years of hydrologic change on southern Tibetan Plateau. Journal of Hydrology, 572, 169-178. doi:https://doi.org/ 10.1016/j.jhydrol.2019.02.054
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  Submitted 12-5-18.
• Chen, F., Shang, H., Panyushkina, I., Meko, D. M., Li, J., Yuan, Y., Yu, S., Chen, F., He, D., & Luo, X. (2019). 500-yr tree-ring reconstruction of Salween River streamflow related to the history of water supply in Southeast Asia. Climate Dynamics, 53(1), 6595-6607. doi:https://doi.org/10.1007/s00382-019-04948-1
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  Submitted 01-03-19.Chen, F., H. Shang, I. Panyushkina, D. Meko, J. Li, Y. Yuan, S. Yu, F. Chen, D. He, and X. Luo (2019b), 500-yr tree-ring reconstruction of Salween River streamflow related to the history of water supply in Southeast Asia, Clim. Dynam., 53(11), 6595–6607, doi:https://doi.org/10.1007/s00382-019-04948-1.
• Fletcher, T., Touchan, R., Lepley, K., Rouini, N., Bloye, R., Tremarelli, T. S., Pena, K., & Meko, D. (2019). Two reconstructions of August-July precipitation for Central Norther Arizona from tree rings. Tree-Ring Research, 75(2), 115-126. doi:https://doi.org/10.3959/1536-1098-75.2.116
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  Product of DISC course, summer of 2017
• Kedziora, W., Touchan, R., Meko, D., Szyc, K., Wojtan, R., Bijak, S., & Tomusiak, R. (2019). The 2019 International Summer School Tree Rings, Climate, Natural Resources, and Human Interactions, Warsaw, Poland. Dendrochronologia, 125631. doi:10.1016/j.dendro.2019.125631
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  Product of DISC course, summer of 2017
• Panyushkina, I., Meko, D. M., Macklin, M. G., Toonen, W. H., Mukhamаdiev, N. S., Konovalov, V. G., Ashikbaev, N. J., & Sagitov, A. O. (2018). Runoff variations in Lake Balkhash Basin, Central Asia, 1779 to 2015, inferred from tree rings. Climate Dynamics, 51(7), 3161-3177. doi:org/10.1007/s00382-018-4072-z
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  Panyushkina, I. P., D. M. Meko, M. G. Macklin, W. H. J. Toonen, N. S. Mukhamdiev,V. G. Konovalov, N. A. Ashikbaev, and A. O. Sagitov (2018), Runoff variations inLake Balkhash Basin, Central Asia, 1779 to 2015, inferred from tree rings, Clim.Dynam., 51 (7), 3161–3177, doi:https://doi.org/10.1007/s00382-018-4072-z.Long highly-resolved proxies for runoff are in high demand for hydrological forecast andwater management in arid Central Asia. An accurate (R2=0.53) reconstruction of Oct- Sept discharge of the Ili River in Kazakhstan, 1779-2015, is developed from moisture-sensitive tree rings of spruce sampled in the Tian Shan Mountains. The five-time fold extension of the gauged discharge record represents the variability of runoff in the Lake Balkhash Basin for the last 235 years. Most reconstructed flow extremes (±2σ) occur outside the historical record (1936-2015) and large dam construction (1969). Decadal variability of the Ili discharge corresponds well with hydrological records of other Eurasian internal drainages modeled with tree rings. The spectral analysis identifies variance peaks (highest near 42 yr) consistent with main hemispheric oscillations of the Eurasian climatic system. Seasonal comparison of the Ili discharge with sea-level-pressure and geopotential height data suggests periods of high flow likely result from the increased contribution of snow to runoff associated with the interaction of Arctic air circulation with Siberian High-Pressure System and North Atlantic Oscillation. The instrumental discharge poorly represents the long-term range of runoff natural variability in the Lake Balkhash basin. The reconstruction shows a 40 yr long interval of low discharge preceded a recent high peak in the first decade of the 2000s followed by a decline to more recent levels of discharge not seen since the start of the gauged record.
• Paul, S., Wright, W. E., Belmecheri, S., Meko, D. M., Leavitt, S. W., Ehleringer, J. R., & Monson, R. K. (2018). Disentangling seasonal and interannual legacies from inferred patterns of forest water and carbon cycling using tree‐ring stable isotopes. Global Change Biology, 00, 1-16. doi:10.1111/gcb.14395
• Babushkina, E. A., Belokopytova, L. V., Grachev, A. M., Meko, D. M., & Vaganov, E. A. (2017). Variation of the hydrological regime of Bele-Shira closed basin in Southern Siberia and its reflection in the radial growth of Larix sibirica. Regional Environmental Change, 1-13. doi:10.1007/s10113-017-1137-1
• Coulthard, B., Touchan, R., Anchukaitis, K. A., & Meko, D. M. (2017). Tree growth and vegetation activity at the ecosystem-scale in the eastern Mediterranean. Environ. Res. Lett., 12(084008), 1-10. doi:https://doi.org/10.1088/ 1748-9326/aa7b26.
• Agafonov, L. I., Meko, D. M., & Panyushkina, I. P. (2016). Reconstruction of Ob river, Russia, discharge from ring widths of floodplain trees. Journal of Hydrology, 543, 198–207. doi:10.1016/ j.jhydrol.2016.09.031
• Cook, B. I., Anchukaitis, K. J., Touchan, R., Meko, D. M., & Cook, E. R. (2016). Spatiotemporal drought variability in the Mediterranean over the last 900 years. J. Geophys. Res-Atmos, 121(5). doi:https://doi.org/10.1002/2015JD023929
• Coulthard, B., Smith, D. J., & Meko, D. M. (2016). Is worst-case scenario streamflow drought underestimated in British Columbia? A 332-year perspective for the south coast, derived from tree-rings. Journal of Hydrology, 534, 205–218. doi:http://dx.doi.org/10. 1016/j.jhydrol.2015.12.03
• Touchan, R., Kherchouche, D., Oudjehih, B., Touchan, H., Slimani, S., & Meko, D. M. (2016). Dendroclimatology and wheat production in Algeria. Journal of Arid Environments, 124, 102-110.
• Touchan, R., Shishov, V. V., Tychkov, I. I., Sivrikaya, F., Attieh, J., Ketmen, M., Stephan, J., Mitsopoulos, I., Christou, A., & Meko, D. M. (2016). Elevation-layered dendroclimatic signal in Eastern Mediterranean tree rings. Environ. Res. Lett., 11(044020). doi:10.1088/1748-9326/11/4/044020
• Touchan, R., Shishov, V., Tychkov, I. I., Sivrikaya, F., Attieh, J., Ketmen, M., Stephan, J., Mitsopoulos, I., Christou, A., & Meko, D. M. (2016). Elevation-Layered Dendroclimatic Signal in Eastern Mediterranean Tree Rings. Enviromental Research Letters.
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  Networks of tree-ring data are commonly applied in statistical reconstruction of spatial fields of climate variables. The importance of elevation to the climatic interpretation of tree-ring networks is addressed using 281 station precipitation records, and a network of 79 tree-ring chronologies from different species and a range of elevations in the Eastern Mediterranean. Cluster analysis of chronologies identifies 6 tree-ring groups, delineated principally by site elevation. Correlation analysis suggests several of the clusters are linked to homogenous elevational moisture regimes. Results imply that climate stations close to the elevations of the tree-ring sites are essential for assessing the seasonal climatic signal in tree-ring chronologies from this region. A broader implication is that the elevations of stations contributing to gridded climate networks should be considered in the design and interpretation of field reconstructions of climate from tree rings. Finally, results suggest elevation-stratified tree-ring networks as a strategy for seasonal climate reconstruction.
• Meko, D. M., & Piovano, E. L. (2015). Editorial note -- special issue Advances in Paleohydrology Research and Applications. Journal of Hydrology, 529, Part 2, 431-432.
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  Editorial note for special issue of J. of Hydrology. Meko and Piovano were guest editors.
• Meko, D. M., Friedman, J. M., Touchan, R., Edmondson, J. R., Griffin, E. R., & Scott, J. A. (2015). Alternative standardization approaches to improving streamflow reconstructions with ring-width indices of riparian trees. Holocene, 25(7), 1093-1101.
• Ault, T. R., Cole, J. E., Overpeck, J. T., Pederson, G. T., & Meko, D. M. (2014). Assessing the Risk of Persistent Drought Using Climate Model Simulations and Paleoclimate Data. Journal of Climate, 27(20), 7529-7549.
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  Projected changes in global rainfall patterns will likely alter water supplies and ecosystems in semiarid regions during the coming century. Instrumental and paleoclimate data indicate that natural hydroclimate fluctuations tend to be more energetic at low (multidecadal to multicentury) than at high (interannual) frequencies. State-of-the-art global climate models do not capture this characteristic of hydroclimate variability, suggesting that the models underestimate the risk of future persistent droughts. Methods are developed here for assessing the risk of such events in the coming century using climate model projections as well as observational (paleoclimate) information. Where instrumental and paleoclimate data are reliable, these methods may provide a more complete view of prolonged drought risk. In the U.S. Southwest, for instance, state-of-the-art climate model projections suggest the risk of a decade-scale megadrought in the coming century is less than 50%; the analysis herein suggests that the risk is at least 80%, and may be higher than 90% in certain areas. The likelihood of longer-lived events (>35 yr) is between 20% and 50%, and the risk of an unprecedented 50-yr megadrought is nonnegligible under the most severe warming scenario (5%-10%). These findings are important to consider as adaptation and mitigation strategies are developed to cope with regional impacts of climate change, where population growth is high and multidecadal megadrought worse than anything seen during the last 2000 years would pose unprecedented challenges to water resources in the region.
• Edmondson, J., Friedman, J., Meko, D., Touchan, R., Scott, J., & Edmondson, A. (2014). Dendroclimatic potential of plains cottonwood (Populus deltoides Subsp. Monilifera) from the northern great plains, USA. Tree-Ring Research, 70(1), 21-30. doi:http://dx.doi.org/10.3959/1536-1098-70.1.21
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  Abstract: A new 368-year tree-ring chronology (A.D. 1643-2010) has been developed in western North Dakota using plains cottonwood (Populus deltoides subsp. monilifera) growing on the relatively undisturbed floodplain of the Little Missouri River in the North Unit of Theodore Roosevelt National Park. We document many slow-growing living trees between 150-370 years old that contradict the common understanding that cottonwoods grow fast and die young. In this northern location, cottonwood produces distinct annual rings with dramatic interannual variability that strongly crossdate. The detrended tree-ring chronology is significantly positively correlated with local growing season precipitation and soil moisture conditions (r = 0.69). This time series shows periods of prolonged low radial tree growth during the known droughts of the instrumental record (e.g. 1931-1939 and 1980-1981) and also during prehistory (e.g. 1816-1823 and 1856-1865) when other paleoclimate studies have documented droughts in this region. Tree rings of cottonwood will be a useful tool to help reconstruct climate, streamflow, and the floodplain history of the Little Missouri River and other northern river systems. Copyright © 2014 by The Tree-Ring Society.
• Touchan, R., Anchukaitis, K. J., Shishov, V. V., Sivrikaya, F., Attieh, J., Ketmen, M., Stephan, J., Mitsopoulos, I., Christou, A., & Meko, D. M. (2014). Spatial patterns of eastern Mediterranean climate influence on tree growth. The Holocene, 24(4), 381-392.
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  The first large-scale network of 79 tree-ring chronologies in the Eastern Mediterranean and Near East (EMNE; 33 degrees N-42 degrees N, 21 degrees E-43 degrees E) is described and analyzed to identify the seasonal climatic signal in indices of annual ring width. Correlation analysis and cluster analysis are applied to tree-ring data and gridded climate data to assess the climate signal embedded in the network in preparation for climate field reconstructions and formal proxy/model intercomparison experiments. The lengths of the 79 combined chronologies range from 89 to 990 years. The monthly correlations and partial correlations reveal a pervasive positive association with May, June, and sometimes July precipitation, positive correlations with winter and spring (December through April) temperatures, and negative relationships with May through July temperature, although as expected, there are site-to-site exceptions to these general patterns. Cluster analysis suggests three groups of sites based on their association with climate. The chronologies for the EMNE have coherent seasonal precipitation and temperature signals across a fairly broad geographical domain. The predominant signal is a positive growth response to May-June precipitation. Collectively, the findings suggest that the network can be exploited to develop season-specific field reconstructions of precipitation and drought history in the EMNE.
• Touchan, R., Christou, A. K., & Meko, D. M. (2014). Six centuries of May-July precipitation in Cyprus from tree rings. Climate Dynamics, 1-12.
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  A May-July precipitation nested reconstruction for the period AD 1415-2010 was developed from multi-century tree-ring records of Pinus nigra, Pinus brutia, and Cedrus brevifolia for Cyprus. Reconstructions were interpreted climatologically.
• Touchan, R., Meko, D. M., & Anchukaitis, K. J. (2014). Dendroclimatology in the Eastern Mediterranean. Radiocarbon, 56(4), S61-S68.
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  Dendroclimatology in the Eastern Mediterranean (EM) region has made important contributions to the understanding of climate variability on timescales of decades to centuries. These contributions, beginning in the mid-20th century, have value for resource management, archaeology, and climatology. A gradually expanding treering network developed by the first author over the past 15 years has been the framework for some of the most important recent advances in EM dendroclimatology. The network, now consisting of 79 sites, has been widely applied in large-scale climatic reconstruction and in helping to identify drivers of climatic variation on regional to global spatial scales. This article reviews EM dendroclimatology and highlights contributions on the national and international scale.
• Griffin, D., Woodhouse, C. A., Meko, D. M., Stahle, D. W., Faulstich, H. L., Carrillo, C., Touchan, R., Castro, C. L., & Leavitt, S. W. (2013). North American monsoon precipitation reconstructed from tree-ring latewood. Geophysical Research Letters, 40(5), 954-958.
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  Abstract: The North American monsoon is a major focus of modern and paleoclimate research, but relatively little is known about interannual- to decadal-scale monsoon moisture variability in the pre-instrumental era. This study draws from a new network of subannual tree-ring latewood width chronologies and presents a 470-year reconstruction of monsoon (June-August) standardized precipitation for southwestern North America. Comparison with an independent reconstruction of cool-season (October-April) standardized precipitation indicates that southwestern decadal droughts of the last five centuries were characterized not only by cool-season precipitation deficits but also by concurrent failure of the summer monsoon. Monsoon drought events identified in the past were more severe and persistent than any of the instrumental era. The relationship between winter and summer precipitation is weak, at best, and not time stable. Years with opposing-sign seasonal precipitation anomalies, as noted by other studies, were anomalously frequent during the mid to late 20th century. © 2013. American Geophysical Union. All Rights Reserved.
• Malevich, S. B., Woodhouse, C. A., & Meko, D. M. (2013). Corrigendum to "Tree-ring reconstructed hydroclimate of the Upper Klamath basin" [J. Hydrol. 495 (2013) 13-22]. Journal of Hydrology, 505, 377-.
• Malevich, S. B., Woodhouse, C. A., & Meko, D. M. (2013). Tree-ring reconstructed hydroclimate of the Upper Klamath basin. Journal of Hydrology, 495, 13-22.
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  Abstract: This work presents the first tree-ring reconstructions of hydroclimate for the Upper Klamath River basin, which stretches from northern California into southern Oregon. The extended record provides a centuries-long perspective on the region's hydroclimatic variability and context for water-related political issues that have erupted in recent years. Reconstructions of water-year precipitation for Klamath Falls, Oregon (extending 1564-2004 and 1000-2010 CE) were developed to compare past drought severity with drought severity of the instrumental record (extending 1896-2011). The reconstructions suggest that variability exhibited during the instrumental period captures extremes of moderate-to-long-duration (6-, 10-, and 20-year) droughts, but not of short (single-year and 3-year) and very long (50-year) droughts, which were more severe during the 11th-13th centuries. The late-16th-century "mega drought" is present in the Klamath River basin, though with less strength than in the neighboring Sacramento River basin. Cool-season storm tracks appear to be a direct driver of hydroclimatic variability, leading to instances of see-saw like relationships with neighboring regions, such as in the mid-14th century. In contrast, the larger area of drought in the 12th century is suggestive of a long-term northward shift in cool-season storm tracks. © 2013 Elsevier B.V.
• Meko, D. M., Touchan, R., Villanueva Diaz, J., Griffin, D., Woodhouse, C. A., Castro, C. L., Carillo, C., & Leavitt, S. W. (2013). Sierra San Pedro Martir, Baja California, cool-season precipitation reconstructed from earlywood width of Abies concolor tree rings. J. of Geophyscial Research-Biogeosciences, 118(4), 1660-1673.
• Stahle, D. W., Griffin, R. D., Meko, D. M., Therrell, M. D., Edmondson, J. R., Cleaveland, M. K., Stahle, L. N., Burnette, D. J., Abatzoglou, J. T., Redmond, K. T., Dettinger, M. D., & Cayan, D. R. (2013). The ancient blue oak woodlands of California: Longevity and hydroclimatic history. Earth Interactions, 17(12).
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  Abstract: Ancient blue oak trees are still widespread across the foothills of the Coast Ranges, Cascades, and Sierra Nevada in California. The most extensive tracts of intact old-growth blue oak woodland appear to survive on rugged and remote terrain in the southern Coast Ranges and on the foothills west and southwest of Mt. Lassen. In the authors' sampling of old-growth stands, most blue oak appear to have recruited to the canopy in the middle to late nineteenth century. The oldest living blue oak tree sampled was over 459 years old, and several dead blue oak logs had over 500 annual rings. Precipitation sensitive tree-ring chronologies up to 700 years long have been developed from old blue oak trees and logs. Annual ring-width chronologies of blue oak are strongly correlated with cool season precipitation totals, streamflow in the major rivers of California, and the estuarine water quality of San Francisco Bay. A new network of 36 blue oak chronologies records spatial anomalies in growth that arise from latitudinal changes in the mean storm track and location of landfalling atmospheric rivers. These long, climate-sensitive blue oak chronologies have been used to reconstruct hydroclimatic history in California and will help to better understand and manage water resources. The environmental history embedded in blue oak growth chronologies may help justify efforts to conserve these authentic old-growth native woodlands.
• Touchan, R., Meko, D. M., Ballesteros-Cánovas, J. A., Sánchez-Salguero, R., Camarero, J. J., Kerchouche, D., Muntan, E., Khabcheche, M., Blanco, J. A., Morata, C. R., Garófano-Gómez, V., Martín, L. A., Alfaro-Sánchez, R., Garah, K., Hevia, A., Madrigal-González, J., Sánchez-Miranda, Á., Shestakova, T. A., & Tabakova, M. (2013). Dendrochronology course in Valsaín forest, Segovia, Spain. Tree-Ring Research, 69(2), 93-100.
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  Abstract: This report describes an international summer course, "Tree Rings, Climate, Natural Resources, and Human Interaction", held in Valsaín, Spain, in summer of 2012. The course, with 14 participants from three countries (Spain, Algeria, and Russia), included basic training in dendrochronology skills as well as applied projects in dendroclimatology, dendroecology and dendrogeomorphology. Copyright © 2013 by The Tree-Ring Society.
• Williams, A. P., Allen, C. D., Macalady, A. K., Griffin, D., Woodhouse, C. A., Meko, D. M., Swetnam, T. W., Rauscher, S. A., Seager, R., Grissino-Mayer, H. D., Dean, J. S., Cook, E. R., Gangodagamage, C., Cai, M., & McDowell, N. G. (2013). Temperature as a potent driver of regional forest drought stress and tree mortality. Nature Climate Change, 3(3), 292-297.
• Woodhouse, C. A., Meko, D. M., Griffin, D., & Castro, C. L. (2013). Tree rings and multiseason drought variability in the lower Rio Grande Basin, USA. Water Resources Research, 49(2), 844-850.
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  Abstract: Agriculture and ranching in semiarid regions often rely on local precipitation during the growing season as well as streamflow from runoff in distant headwaters. Where snowpack and reservoir storage are important, this pattern of reliance leads to vulnerability to multiseason drought. The lower Rio Grande basin in New Mexico, used as a case study here, has experienced drought conditions over the past 12 years characterized both by low local summer monsoon precipitation and by reduced availability of surface water supplies from the upper Rio Grande. To place this drought in a long-term context, we evaluate the covariability of local warm-season and remote cool-season hydroclimate over both the modern period and past centuries. We draw on a recently developed network of tree-ring data that allows an assessment of preinstrumental warm-season variations in precipitation over the southwest. Both instrumental and paleoclimatic data suggest that low runoff followed by a dry monsoon is not unusual, although over the full reconstruction period (1659-2008), years with wet or dry conditions shared in both seasons do not occur significantly more often than unshared conditions. Low flows followed by dry monsoon conditions were most persistent in the 1770s and 1780s; other notable periods of shared seasonal droughts occurred in the 1660s and 1950s. The recent drought does not yet appear to be unusually severe in either the instrumental or paleoclimatic context. © 2013. American Geophysical Union. All Rights Reserved.
• Meko, D. M., Woodhouse, C. A., & Morino, K. (2012). Dendrochronology and links to streamflow. Journal of Hydrology, 412-413, 200-209.
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  Abstract: Streamflow variability on timescales of decades to centuries becomes increasingly important as water managers grapple with shortages imposed by increasing demand and limited supply, and possibly exacerbated by climate change. Two applications of dendrochronology to the study of flow variability are illustrated for an existing 1244-yr reconstruction of annual flows of the Colorado River at Lees Ferry, Arizona, USA: (1) identification and climatological interpretation of rare flow events, and (2) assessment of vulnerability of water-supply systems to climatic variability. Analysis centers on a sustained drought of the mid-1100s characterized by persistent low flows on both the Colorado and Sacramento Rivers. Analysis of geopotential height anomalies during modern joint-droughts suggests more than one mode of circulation might accompany joint-drought in the two basins. Monte Carlo simulation is used to demonstrate that a drought as severe as that in the 1100s on the Colorado River might be expected about once in every 4-6 centuries by chance alone given the time-series properties of the modern gaged flows. Application of a river-management model suggests a mid-1100s-style drought, were it to occur today, would drop reservoir levels in Lake Mead to dead-pool within a few decades. Uncertainty presents challenges to accurately quantifying severe sustained droughts from streamflow reconstructions, especially early in the tree-ring record. Corroboration by multiple proxy records is essential. Future improvements are likely to require a combination of methodological advancements and expanded basic data. © 2010 Elsevier B.V.
• Touchan, R., Shishov, V. V., Meko, D. M., Nouiri, I., & Grachev, A. (2012). Process based model sheds light on climate sensitivity of Mediterranean tree-ring width. Biogeosciences, 9(3), 965-972.
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  Abstract: We use the process-based VS (Vaganov-Shashkin) model to investigate whether a regional Pinus halepensis tree-ring chronology from Tunisia can be simulated as a function of climate alone by employing a biological model linking day length and daily temperature and precipitation (AD 1959-2004) from a climate station to ring-width variations. We check performance of the model on independent data by a validation exercise in which the model's parameters are tuned using data for 1982-2004 and the model is applied to generate tree-ring indices for 1959-1981. The validation exercise yields a highly significant positive correlation between the residual chronology and estimated growth curve (rCombining double low line0.76 p
• Ciancarelli, B., Griffin, D., Touchan, R., Meko, D. M., Wright, W. E., Castro, C. L., Woodhouse, C. A., & Leavitt, S. W. (2011). The North American monsoon in the U.S. Southwest: Potential for investigation with tree-ring carbon isotopes. Quaternary International, 235(1-2), 101-107.
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  Abstract:The North American Monsoon (NAM) contributes critical summer moisture to the U.S. Southwest from July through September, but instrumental records of monsoon precipitation are limited to 100 years or less. Tree-ring investigation offers a means of improving our understanding of its long-term spatial and temporal variability. Available evidence indicates the stable-carbon isotopic composition (δ13C) of tree rings in this region is strongly linked to moisture. In addition to latewood width as a precipitation proxy, the δ13C of latewood also appears to be a strong proxy, largely manifesting water stress effects on stomatal conductance and their consequence to isotopic discrimination against 13CO2. In one promising study, the δ13C of 11 years of latewood from 8 sites regressed against their corresponding precipitation exhibited a coefficient of -0.061‰ per cm of July + August + September precipitation (r2 = 0.41). Long latewood δ13C chronologies are currently being developed from tree rings of ponderosa pine and Douglas-fir at several sites in NAM core regions in the Southwest to evaluate its usefulness in supplementing precipitation reconstructions derived from latewood widths. Among planned outcomes, the improved monsoon precipitation records can be used to better evaluate natural variability of NAM precipitation and its linkage to winter precipitation, document the character of monsoon season droughts, and test accuracy of regional climate models. © 2010 Elsevier Ltd and INQUA.
• Griffin, D., Meko, D. M., Touchan, R., Leavitt, S. W., & Woodhouse, C. A. (2011). Latewood chronology development for summer-moisture reconstruction in the US Southwest. Tree-Ring Research, 67(2), 87-101.
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  Abstract: Tree-ring studies have demonstrated that conifer latewood measurements contain information on long-term North American monsoon (NAM) variability, a hydroclimatic feature of great importance to plants, animals, and human society in the US Southwest. This paper explores data-treatment options for developing latewood chronologies aimed at NAM reconstruction. Archived wood samples for five Douglas-fir (Pseudotsuga menziesii, Mirb. Franco) sites in southeastern Arizona are augmented with new collections. The combined dataset is analyzed along with time series of regionally averaged observed precipitation to quantify the strength of regional precipitation signal in latewood time series and to identify ways of increasing the signal strength. Analysis addresses the signal strength influences of including or excluding "false" latewood bands in the nominal "latewood" portion of the ring, the necessary adjustment of latewood width for statistical dependence on antecedent earlywood width, and tree age. Results suggest that adjusted latewood width chronologies from individual sites can explain around 30% of the variance of regional summer (July-August) precipitation - increasing to more than 50% with use of multiple chronologies. This assessment is fairly insensitive to the treatment of false latewood bands (in intra-annual width and δ 13C variables), and to whether latewood-width is adjusted for dependence on earlywood-width at the core or site level. Considerations for operational chronology development in future studies are (1) large tree-to-tree differences in moisture signal, (2) occasional nonlinearity in EW-LW dependence, and (3) extremely narrow and invariant latewood width in outer portions of some cores. A protocol for chronology development addressing these considerations is suggested. © 2011 The Tree-Ring Society.
• Margolis, E. Q., Meko, D. M., & Touchan, R. (2011). A tree-ring reconstruction of streamflow in the Santa Fe River, New Mexico. Journal of Hydrology, 397(1-2), 118-127.
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  Abstract: The upper Santa Fe River provides up to 50% of the water supply for the growing population of Santa Fe, NM. Recent droughts have dramatically lowered reservoir levels and raised concern about the future of the water supply, particularly when combined with projections of a warmer and drier future climate. In this study, new and updated tree-ring chronologies are used to reconstruct annual discharge for the upper Santa Fe River and place the short period of gaged flows, 1914-2007, in a long-term context. Principal components analysis and forward stepwise multiple linear regression were used to produce two reconstructions: (1) a better fit, " short reconstruction" (adjusted R 2=0.62, 1592-2007) and (2) a less robust, " long reconstruction" (adj. R 2=0.50, 1305-2007). Both reconstructions indicate that recent extreme low flow events (e.g., 2002) are rare (5th percentile) in the long-term records and that the 1950s drought contained the lowest 7-year mean flows over the past 400-700years. However, longer, multi-decadal dry periods not present in the gaged flows occurred in the past. For example, the 40-year mean for 1544-1583 is estimated at just 86% of the 1914-2007 mean. During extended dry periods in the 16th and 18th centuries the probability that annual flow would not meet the current surface water allocation and instream flow target (7.52 million cubic meters, MCM) was up to 10% greater (78.7% non-exceedence probability) than during the instrumental period. The results indicate that the gaged record does not contain the full range of high and low flows or the variability in the probability distributions of flows present in the long-term record. Therefore current and future water management and planning based on the instrumental period may not adequately buffer against the natural variability in the climate and streamflow systems. This valuable paleo-hydrologic information is in the process of being incorporated into water supply planning for the City of Santa Fe (e.g., modeling future water supply scenarios directly from reconstructed periods of streamflow). © 2010 Elsevier B.V.
• Meko, D. M., Stahle, D. W., Griffin, D., & Knight, T. A. (2011). Inferring precipitation-anomaly gradients from tree rings. Quaternary International, 235(1-2), 89-100.
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  Abstract: Long-term information on gradients in precipitation-anomaly over tens to hundreds of km is important to hydroclimatology for improved understanding of the spatiotemporal variability of moisture-delivery systems and runoff. Site-centered reconstructions of cool-season (Nov-Apr) precipitation at 36 Quercus douglasii tree-ring sites in the Central Valley of California, USA, are generated, regionalized, and evaluated for ability to track north-south gradients in precipitation-anomaly. Event series are constructed for overall-wet (W), overall-dry (D), wetter-to-north (W/D) and wetter-to-south (D/W) conditions, 1557-2001. Interesting features of the event series are clustering of W events in the 1780-1790s and a three-year run of D/W events in 1816-1818 (coincidentally following the eruption of Tambora in 1815). The most recent 25 years of the event series stand out for a high frequency of W and D events and low frequency of events associated with strong gradients in precipitation-anomaly. The five strongest W events in this period and seven of the nine W events since 1934 match El Niño years. Recent changes in the event series may be a Central-Valley footprint of a well-documented post-1976 change in the atmosphere-ocean climate system over the North Pacific. Similar studies may prove useful in other geographical areas where networks of tree-ring data sufficiently sensitive to precipitation are available. © 2010 Elsevier Ltd and INQUA.
• Meko, D. M., Touchan, R., & Anchukaitis, K. J. (2011). Seascorr: A MATLAB program for identifying the seasonal climate signal in an annual tree-ring time series. Computers and Geosciences, 37(9), 1234-1241.
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  Abstract: A common research task in dendroclimatology is identification of the monthly or seasonal climate signal in an annual time series of indices of ring width. A MATLAB function, seascorr, is introduced as a general statistical tool for identifying the signal. Monthly time series of primary and secondary climate variables are input to the function along with a tree-ring time series and specifications for seasonal groupings. The relationship of the tree-ring series with the seasonalized primary climate variable is summarized by simple correlations. The relationship with the secondary climate variable is summarized by partial correlations, controlling for the influence of the primary climate variable. Confidence intervals on sample correlations and partial correlations are estimated with the help of Monte Carlo simulation of the tree-ring series by exact simulation, which preserves the spectral properties of the observed series. Results are summarized in graphical and statistical output. The function is illustrated with examples from Tunisia and Russia. © 2011 Elsevier Ltd.
• Stambaugh, M. C., Guyette, R. P., McMurry, E. R., Cook, E. R., Meko, D. M., & Lupo, A. R. (2011). Drought duration and frequency in the U.S. Corn Belt during the last millennium (AD 992-2004). Agricultural and Forest Meteorology, 151(2), 154-162.
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  Abstract: Drought is among the most costly natural hazards affecting the United States, averaging $6 to $8 billion annually in damages, primarily in crop losses. Mitigating the impacts of drought through planning and preparedness has the potential to save billions of dollars. We used a new long tree-ring chronology developed from the central U.S. to reconstruct annual drought and characterize past drought duration, frequency, and cycles in the U.S. Corn Belt region during the last millennium. This is the first paleoclimate reconstruction achieved with subfossil oak wood in the U.S. and increases the current dendroclimatic record in the central U.S. agricultural region by over 500 years. A tree ring-width drought response function was calibrated and verified against monthly instrumental Palmer Hydrologic Drought Index (PHDI) during the summer season (JJA). Separate reconstructions tailored to emphasize high-frequency and low-frequency variations indicate that drought conditions over the period of instrumental records (since 1895) do not exhibit the full range of variability, severity, or duration of droughts during the last millennium. For example, three years in the last millennium were drier than 1934, a classic Dust-Bowl year and the driest year of the instrumental period. Thirteen decadal to multidecadal droughts (i.e., ≥10 years) occurred during the last millennium - the longest lasting sixty-one years and centered on the late twelfth century. Reconstructions exhibited quasi-periodicity at bidecadal and century-scale periods. Significant rhythms in drought were identified near 20-yr and 128-yr periods. The tree-ring drought reconstruction shows promise in providing new information about long-term climate variability in the agricultural regions that could potentially span multimillennia. We postulate that tree-ring chronologies (i.e., tree growth), thus far under-utilized in agricultural applications, have the potential to match contributions of instrumental climate data. © 2010 Elsevier B.V.
• Touchan, R., Anchukaitis, K. J., Meko, D. M., Sabir, M., Attalah, S., & Aloui, A. (2011). Spatiotemporal drought variability in northwestern Africa over the last nine centuries. Climate Dynamics, 37(1), 237-252.
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  Abstract: Changes in precipitation patterns and the frequency and duration of drought are likely to be the feature of anthropogenic climate change that will have the most direct and most immediate consequences for human populations. The latest generation of state-of-the-art climate models project future widespread drying in the subtropics. Here, we reconstruct spatially-complete gridded Palmer drought severity index values back to A. D. 1179 over Morocco, Algeria, and Tunisia. The reconstructions provide long-term context for northwest African hydroclimatology, revealing large-scale regional droughts prior to the sixteenth century, as well as more heterogeneous patterns in sixteenth, eighteenth, and twentieth century. Over the most recent decades a shift toward dry conditions over the region is observed, which is consistent with general circulation model projections of greenhouse gas forced enhanced regional subtropical drought. © 2010 Springer-Verlag.
• Touchan, R., Woodhouse, C. A., Meko, D. M., & Allen, C. (2011). Millennial precipitation reconstruction for the Jemez Mountains, New Mexico, reveals changingb drought signal. International Journal of Climatology, 31(6), 896-906.
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  Abstract: Drought is a recurring phenomenon in the American Southwest. Since the frequency and severity of hydrologic droughts and other hydroclimatic events are of critical importance to the ecology and rapidly growing human population of this region, knowledge of long-term natural hydroclimatic variability is valuable for resource managers and policy-makers. An October-June precipitation reconstruction for the period AD 824-2007 was developed from multi-century tree-ring records of Pseudotsuga menziesii (Douglas-fir), Pinus strobiformis (Southwestern white pine) and Pinus ponderosa (Ponderosa pine) for the Jemez Mountains in Northern New Mexico. Calibration and verification statistics for the period 1896-2007 show a high level of skill, and account for a significant portion of the observed variance (>50%) irrespective of which period is used to develop or verify the regression model. Split-sample validation supports our use of a reconstruction model based on the full period of reliable observational data (1896-2007). A recent segment of the reconstruction (2000-2006) emerges as the driest 7-year period sensed by the trees in the entire record. That this period was only moderately dry in precipitation anomaly likely indicates accentuated stress from other factors, such as warmer temperatures. Correlation field maps of actual and reconstructed October-June total precipitation, sea surface temperatures and 500-mb geopotential heights show characteristics that are similar to those indicative of El Niño-Southern Oscillation patterns, particularly with regard to ocean and atmospheric conditions in the equatorial and north Pacific. Our 1184-year reconstruction of hydroclimatic variability provides long-term perspective on current and 20th century wet and dry events in Northern New Mexico, is useful to guide expectations of future variability, aids sustainable water management, provides scenarios for drought planning and as inputs for hydrologic models under a broader range of conditions than those provided by historical climate records. © 2010 Royal Meteorological Society.
• George, S. S., Meko, D. M., & Cook, E. R. (2010). The seasonality of precipitation signals embedded within the North American Drought Atlas. Holocene, 20(6), 983-988.
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  Abstract: We examine how the seasonality of precipitation signals embedded within the North American Drought Atlas varies across the continent. Instrumental records of average summer (JJA) Palmer Drought Severity Index (PDSI) are characterized by major regional differences in the relative importance of precipitation during summer and winter (DJF). The Atlas, which is based on a network of drought-sensitive tree-ring records, is able to reproduce the main geographic patterns of these biases, but tree-ring reconstructions exaggerate the influence of seasonal precipitation anomalies in the southwestern United States and northern Mexico (towards a stronger winter signal) and western Canada (towards a stronger summer signal). Drought reconstructions from the Southwest and Tex-Mex regions are tuned mainly to winter precipitation and display strong teleconnections to both El Niño and La Niña. In contrast, winter precipitation signals are either weak or absent in drought reconstructions from northwestern North America, and tree-ring estimates of PDSI show a much less robust association with the El Niño-Southern Oscillation. Geographical differences in the relative strength of seasonal precipitation signals are likely due to (i) local factors that influence tree growth but are not incorporated into the PDSI algorithm and (ii) real differences in regional climatology. These seasonal biases must be taken into account when comparing drought reconstructions across North America, when comparing tree-ring PDSI to drought records developed from other proxies or when attempting to use the Drought Atlas to link past droughts to potential forcing mechanisms. © 2010 The Author(s).
• Knight, T. A., Meko, D. M., & Baisan, C. H. (2010). A bimillennial-length tree-ring reconstruction of precipitation for the Tavaputs Plateau, Northeastern Utah. Quaternary Research, 73(1), 107-117.
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  Abstract: Despite the extensive network of moisture-sensitive tree-ring chronologies in western North America, relatively few are long enough to document climatic variability before and during the Medieval Climate Anomaly (MCA) ca. AD 800-1300. We developed a 2300-yr tree-ring chronology extending to 323 BC utilizing live and remnant Douglas-fir (Pseudotsuga menziesii) from the Tavaputs Plateau in northeastern Utah. A resulting regression model accounts for 70% of the variance of precipitation for the AD 1918-2005 calibration period. Extreme wet and dry periods without modern analogues were identified in the reconstruction. The MCA is marked by several prolonged droughts, especially prominent in the mid AD 1100s and late 1200s, and a lack of wet or dry single-year extremes. The frequency of extended droughts is not markedly different, however, than before or after the MCA. A drought in the early AD 500s surpasses in magnitude any other drought during the last 1800 yr. A set of four long high-resolution records suggests this drought decreased in severity toward the south in the western United States. The spatial pattern is consistent with the western dipole of moisture anomaly driven by El Niño and is also similar to the spatial footprint of the AD 1930s "Dust Bowl" drought. © 2009 Elsevier Inc. on behalf of University of Washington.
• Woodhouse, C. A., Meko, D. M., MacDonald, G. M., Stahle, D. W., & Cook, E. R. (2010). A 1,200-year perspective of 21st century drought in southwestern North America. Proceedings of the National Academy of Sciences of the United States of America, 107(50), 21283-21288.
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  PMID: 21149683;PMCID: PMC3003080;Abstract: A key feature of anticipated 21st century droughts in Southwest North America is the concurrence of elevated temperatures and increased aridity. Instrumental records and paleoclimatic evidence for past prolonged drought in the Southwest that coincide with elevated temperatures can be assessed to provide insights on temperature-drought relations and to develop worst-case scenarios for the future. In particular, during the medieval period, ∼AD 900-1300, the Northern Hemisphere experienced temperatures warmer than all but the most recent decades. Paleoclimatic and model data indicate increased temperatures in western North America of approximately 1 °C over the long-term mean. This was a period of extensive and persistent aridity over western North America. Paleoclimatic evidence suggests drought in the mid-12th century far exceeded the severity, duration, and extent of subsequent droughts. The driest decade of this drought was anomalously warm, though not as warm as the late 20th and early 21st centuries. The convergence of prolonged warming and arid conditions suggests the mid-12th century may serve as a conservative analogue for severe droughts that might occur in the future. The severity, extent, and persistence of the 12th century drought that occurred under natural climate variability, have important implications for water resource management. The causes of past and future drought will not be identical but warm droughts, inferred from paleoclimatic records, demonstrate the plausibility of extensive, severe droughts, provide a long-term perspective on the ongoing drought conditions in the Southwest, and suggest the need for regional sustainability planning for the future.
• George, S. S., Meko, D. M., Girardin, M., MacDonald, G. M., Nielsen, E., Pederson, G. T., Sauchyn, D. J., Tardif, J. C., & Watson, E. (2009). The tree-ring record of drought on the Canadian Prairies. Journal of Climate, 22(3), 689-710.
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  Abstract: Ring-width data from 138 sites in the Canadian Prairie Provinces and adjacent regions are used to estimate summer drought severity during the past several hundred years. The network was divided into five regional groups based on geography, tree species, and length of record: the eastern Rockies, northern Saskatchewan, central Manitoba, southern Manitoba, and northwestern Ontario. Regional tree-ring records are primarily related to summer moisture and drought conditions, and are less responsive to droughts caused by deficits in winter precipitation. These summer-sensitive data are not linearly related to major modes of climate variability, including ENSO and the Pacific decadal oscillation (PDO), which primarily affect the climate of western Canada during winter. Extended drought records inferred from tree rings indicate that drought on the Canadian Prairies has exhibited considerable spatial heterogeneity over the last several centuries. For northern Saskatchewan and northwestern Ontario, intervals of persistently low tree growth during the twentieth century were just as long as or longer than low-growth intervals in the eighteenth or nineteenth centuries. Longer records from southern Alberta suggest that the most intense dry spell in that area during the last 500 yr occurred during the 1720s. At the eastern side of the prairies, the longest dry event is centered around 1700 and may coincide with low lake stands in Manitoba, Minnesota, and North Dakota. Although the Canadian Prairies were dry at times during the 1500s, there is no regional analog to the sixteenth-century "megadrought" that affected much of the western United States and northern Mexico. © 2009 American Meteorological Society.
• Stahle, D. W., Cleaveland, M. K., Grissino-Mayer, H., Griffin, R. D., Fye, F. K., Therrell, M. D., Burnette, D. J., Meko, D. M., & Diaz, J. V. (2009). Cool- and warm-season precipitation reconstructions over western New Mexico. Journal of Climate, 22(13), 3729-3750.
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  Abstract: Precipitation over the southwestern United States exhibits distinctive seasonality, and contrasting ocean-atmospheric dynamics are involved in the interannual variability of cool- and warm-season totals. Tree-ring chronologies based on annual-ring widths of conifers in the southwestern United States are well correlated with accumulated precipitation and have previously been used to reconstruct cool-season and annual precipitation totals. However, annual-ring-width chronologies cannot typically be used to derive a specific record of summer monsoon-season precipitation. Some southwestern conifers exhibit a clear anatomical transition from the earlywood and latewood components of the annual ring, and these exactly dated sub-annual ring components can be measured separately and used as unique proxies of cool- and warm-season precipitation and their associated large-scale ocean-atmospheric dynamics. Two 2139-yr-long reconstructions of cool- (November-May) and early-warm season (July) precipitation have been developed from ancient conifers and relict wood at El Malpais National Monument, New Mexico. Both reconstructions have been verified on independent precipitation data and reproduce the spatial correlation patterns detected in the large-scale SST and 500-mb height fields using instrumental precipitation data from New Mexico. Above-average precipitation in the cool-season reconstruction is related to El Niño conditions and to the positive phase of the Pacific decadal oscillation. Above-average precipitation in July is related to the onset of the North American monsoon over New Mexico and with anomalies in the 500-mb height field favoring moisture advection into the Southwest from the North Pacific, the Gulf of California, and the Gulf of Mexico. Cool-and warm-season precipitation totals are not correlated on an interannual basis in the 74-yr instrumental or 2139-yr reconstructed records, but wet winter-spring extremes tend to be followed by dry conditions in July and very dry winters tend to be followed by wet Julys in the reconstructions. This antiphasing of extremes could arise from the hypothesized cool- to early-warm-season change in the sign of large-scale ocean-atmospheric forcing of southwestern precipitation, from the negative land surface feedback hypothesis in which winter-spring precipitation and snow cover reduce surface warming and delay the onset of the monsoon, or perhaps from an interaction of both large-scale and regional forcing. Episodes of simultaneous interseasonal drought ("perfect" interseasonal drought) persisted for a decade or more during the 1950s drought of the instrumental era and during the eighth- and sixteenth-century droughts, which appear to have been two of the most profound droughts over the Southwest in the past 1400 yr. Simultaneous interseasonal drought is doubly detrimental to dry-land crop yields and is estimated to have occurred during the mid-seventeenth-century famines of colonial New Mexico but was less frequent during the late-thirteenth-century Great Drought among the Anasazi, which was most severe during the cool season. © 2009 American Meteorological Society.
• George, S. S., Meko, D. M., & Evans, M. N. (2008). Regional tree growth and inferred summer climate in the Winnipeg River basin, Canada, since AD 1783. Quaternary Research, 70(2), 158-172.
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  Abstract: A network of 54 ring-width chronologies is used to estimate changes in summer climate within the Winnipeg River basin, Canada, since AD 1783. The basin drains parts of northwestern Ontario, northern Minnesota and southeastern Manitoba, and is a key area for hydroelectric power production. Most chronologies were developed from Pinus resinosa and P. strobus, with a limited number of Thuja occidentalis, Picea glauca and Pinus banksiana. The dominant pattern of regional tree growth can be recovered using only the nine longest chronologies, and is not affected by the method used to remove variability related to age or stand dynamics from individual trees. Tree growth is significantly, but weakly, correlated with both temperature (negatively) and precipitation (positively) during summer. Simulated ring-width chronologies produced by a process model of tree-ring growth exhibit similar relationships with summer climate. High and low growth across the region is associated with cool/wet and warm/dry summers, respectively; this relationship is supported by comparisons with archival records from early 19th century fur-trading posts. The tree-ring record indicates that summer droughts were more persistent in the 19th and late 18th century, but there is no evidence that drought was more extreme prior to the onset of direct monitoring. Crown Copyright © 2008.
• MacDonald, G. M., Stahle, D. W., Diaz, J. V., Beer, N., Busby, S. J., Cerano-Paredes, J., Cole, J. E., Cook, E. R., End-Field, G., Gutierrez-Garcia, G., Hall, B., Magana, V., Meko, D. M., Méndez-Pérez, M., Sauchyn, D. J., Watson, E., & Woodhouse, C. A. (2008). Climate warming and 21st-century drought in southwestern North America. Eos, 89(9), 82-.
• Touchan, R., Anchukaitis, K. J., Meko, D. M., Attalah, S., Baisan, C., & Aloui, A. (2008). Long term context for recent drought in northwestern Africa. Geophysical Research Letters, 35(13).
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  Abstract: Anthropogenic climate change is projected to exacerbate midlatitude aridity. Here, we analyze newly developed multi-century tree-ring records for a long-term perspective on drought in Tunisia and Algeria. We use a new set of 13 Cedrus adantica and Pinus halepensis chronologies with a strong signal for warm-season drought (May-August) to generate a robust, well-validated reconstruction of the Palmer Drought Severity Index (PDSI) for the period AD 1456-2002. Key features of the reconstruction reveal the magnitude of pre-instrumental droughts from the historic record. Remarkably, the most recent drought (1999-2002) appears to be the worst since at least the middle of the 15th century. This drought is consistent with the early signature of a transition to more and midlatitude conditions, as projected by general circulation models. Copyright 2008 by the American Geophysical Union.
• Touchan, R., Meko, D. M., & Aloui, A. (2008). Precipitation reconstruction for Northwestern Tunisia from tree rings. Journal of Arid Environments, 72(10), 1887-1896.
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  Abstract: An October-June precipitation reconstruction was developed from a Pinus halepensis regional tree-ring chronology from four sites in northwestern Tunisia for the period of 1771-2002. The reconstruction is based on a reliable and replicable statistical relationship between climate and tree-ring growth and shows climate variability on both interannual and interdecadal time scales. Thresholds (12th and 88th percentiles) based on the empirical cumulative distribution of observed precipitation for the 1902-2002 calibration period were used to delineate dry years and wet years of the long-term reconstruction. The longest reconstructed drought by this classification in the 232-year reconstruction is 2 years, which occurred in the 19th century. Analysis of 500 mb height data for the period 1948-2002 suggests reconstructed extreme dry and wet events can provide information on past atmospheric circulation anomalies over a broad region including the Mediterranean, Europe and eastern Asia. © 2008 Elsevier Ltd. All rights reserved.
• Meko, D. M., Woodhouse, C. W., Baisan, C. H., Lukas, J. J., Hughes, M. K., & Salzer, M. W. (2007). Medieval drought in the Upper Colorado River Basin. Geophys. Res. Lett., 34, 10, L10705. doi:10.1029/2007GL029988
• Shamir, E., Meko, D. M., Graham, N. E., & Georgakakos, K. P. (2007). Hydrologic model framework for water resources planning in the Santa Cruz River, Southern Arizona. Journal of the American Water Resources Association, 43(5), 1155-1170.
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  Abstract: The authors develop a model framework that includes a set of hydrologic modules as a water resources management and planning tool for the upper Santa Cruz River near the Mexican border, Southern Arizona. The modules consist of: (1) stochastic generation of hourly precipitation scenarios that maintain the characteristics and variability of a 45-year hourly precipitation record from a nearby rain gauge; (2) conceptual transformation of generated precipitation into daily streamflow using varied infiltration rates and estimates of the basin antecedent moisture conditions; and (3) surface-water to ground-water interaction for four downstream microbasins that accounts for alluvial ground-water recharge, and ET and pumping losses. To maintain the large inter-annual variability of streamflow as prevails in Southern Arizona, the model framework is constructed to produce three types of seasonal winter and summer categories of streamflow (i.e., wet, medium, or dry). Long-term (i.e., 100 years) realizations (ensembles) are generated by the above described model framework that reflects two different regimes of inter annual variability. The first regime is that of the historic streamflow gauge record. The second regime is that of the tree ring reconstructed precipitation, which was derived for the study location. Generated flow ensembles for these two regimes are used to evaluate the risk that the regional four ground-water microbasins decline below a preset storage threshold under different operational water utilization scenarios. © 2007 Hydrologic Research Center.
• Meko, D. M. (2006). Tree-ring inferences on water-level fluctuations of Lake Athabasca. Canadian Water Resources Journal, 31(4), 229-248.
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  Abstract: Tree-ring data were analyzed for a long-term perspective on ecological and hydroclimatic variations on the Peace-Athabasca Delta (PAD).The ecosystem of this Ramsar Wetland of International Importance in northeastern Alberta is sensitive to fluctuations in water levels of the numerous lakes, channels and perched basins, and attention has been focused in recent decades on the possibility of deleterious effects from climatic change and regulation of the Peace River by W.A.C. Bennett Dam. A network of eight Piceaglauca tree-ring chronologies was developed, time series features of growth variation were summarized, and the chronologies were applied in a regression model to reconstruct an annual time series of early summer (July 11 to 20) water levels of Lake Athabasca for the period A.D. 1801-1999. Though statistically weak (R2 = 0.36), the reconstruction verifies adequately in cross-validation and is consistent with anecdotal written records of a dramatic decline in water levels in 1879-81. Correlation of reconstructed and observed water levels improves with smoothing. Gaussian smoothing (ten years and longer) identifies a major low centred on 1890. The differential growth responses among the sites as well as evidence from other tree-ring studies suggest the 1890 low was associated primarily with diminished Peace River flows. The 20th century is unusual in a long-term context for high-amplitude multi-decadal variations in tree growth and reconstructed water levels, but the timing of these more recent fluctuations appears unrelated to the building of the W.A.C. Bennett Dam. Further research is needed to better discriminate the tree-ring signal for lake-level variation from the signal due to localized precipitation. © 2006 Canadian Water Resources Association.
• Woodhouse, C. A., Gray, S. T., & Meko, D. M. (2006). Updated streamflow reconstructions for the Upper Colorado River Basin. Water Resources Research, 42(5).
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  Abstract: Updated proxy reconstructions of water year (October-September) streamflow for four key gauges in the Upper Colorado River Basin were generated using an expanded tree ring network and longer calibration records than in previous efforts. Reconstructed gauges include the Green River at Green River, Utah; Colorado near Cisco, Utah; San Juan near Bluff, Utah; and Colorado at Lees Ferry, Arizona. The reconstructions explain 72-81% of the variance in the gauge records, and results are robust across several reconstruction approaches. Time series plots as well as results of cross-spectral analysis indicate strong spatial coherence in runoff variations across the subbasins. The Lees Ferry reconstruction suggests a higher long-term mean than previous reconstructions but strongly supports earlier findings that Colorado River allocations were based on one of the wettest periods in the past 5 centuries and that droughts more severe than any 20th to 21st century event occurred in the past. Copyright 2006 by the American Geophysical Union.
• Meko, D. M., & Woodhouse, C. A. (2005). Tree-ring footprint of joint hydrologic drought in Sacramento and Upper Colorado river basins, western USA. Journal of Hydrology, 308(1-4), 196-213.
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  Abstract: Growing and changing demands on water supply, along with natural climate variability and possible anthropogenically induced climate change, make water resource management and planning increasingly challenging, particularly in arid regions. Instrumental climate and gaged streamflow records provide just a snapshop of recent natural hydrologic variability. In this paper, we use tree-ring-based annual streamflow reconstructions for the Sacramento River in California and the Blue River in western Colorado to analyze the temporal and spatial variability of widespread drought simultaneously affecting both basins over the past five centuries. Stability of joint-drought episodes and the covariation of reconstructed flows in the two basins are analyzed with sliding correlations, spectral analysis and a hypergeometric test. Year-to-year spatial patterns of moisture anomalies in a singular joint-drought episode in the late-1500s are mapped with a network of tree-ring data. Climatological aspects of joint droughts of the 20th century are investigated with 500-mb geopotential height data and climatic indices. Although flow in the two rivers is only very weakly correlated over the full 538-yr reconstruction period, more years of joint drought occur than would be expected by chance alone. Covariation in reconstructed flows is stronger in the late 1500s and mid-1700s than at any time since 1800. The late 1500s period of drought is not characterized as a decades-long unbroken drought, but as a series of drought impulses broken by wet years, with widespread moisture deficits in joint dry years. Periods of high inter-basin correlation in reconstructed flow are characterized by coherency at frequencies within the ENSO band. However, joint droughts in instrumental gage records do not display any consistent relationship with ENSO or the Pacific Decadal Oscillation (PDO), and so it is difficult to infer either as a causal mechanism for joint droughts in the past. © 2004 Elsevier B.V. All rights reserved.
• Cook, E. R., Woodhouse, C. A., Eakin, C. M., Meko, D. H., & Stahle, D. W. (2004). Long-term aridity changes in the western United States. Science, 306(5698), 1015-1018.
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  PMID: 15472040;Abstract: The western United States is experiencing a severe multiyear drought that is unprecedented in some hydroclimatic records. Using gridded drought reconstructions that cover most of the western United States over the past 1200 years, we show that this drought pales in comparison to an earlier period of elevated aridity and epic drought in AD 900 to 1300, an interval broadly consistent with the Medieval Warm Period. If elevated aridity in the western United States is a natural response to climate warming, then any trend toward warmer temperatures in the future could lead to a serious long-term increase in aridity over western North America.
• Skirvin, S. M., Marsh, S. E., McClaran, M. P., & Meko, D. M. (2003). Climate spatial variability and data resolution in a semi-arid watershed, south-eastern Arizona. Journal of Arid Environments, 54(4), 667-686.
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  Abstract: In the 10,000 km2 San Pedro River watershed area in south-eastern Arizona, high-resolution spatial patterns of long-term precipitation and temperature were better reproduced by kriging climate data with elevation as external drift (KED) than by multiple linear regression on station location and elevation as judged by the spatial distribution of interpolation error. Mean errors were similar overall, and interpolation accuracy for both methods increased with increasing correlation between climate variables and elevation. Uncertainty in station locations had negligible effect on mean estimation error, although error for individual stations varied as much as 27%. Our future ability to examine spatial aspects of climate change at high spatial resolution will be severely limited by continuing closures of climate stations in this part of the United States. © 2003 Elsevier Science Ltd.
• Benson, L., Kashgarian, M., Rye, R., Lund, S., Paillet, F., Smoot, J., Kester, C., Mensing, S., Meko, D., & Lindström, S. (2002). Holocene multidecadal and multicentennial droughts affecting Northern California and Nevada. Quaternary Science Reviews, 21(4-6), 659-682.
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  Abstract: Continuous, high-resolution δ18O records from cored sediments of Pyramid Lake, Nevada, indicate that oscillations in the hydrologic balance occurred, on average, about every 150 years (yr) during the past 7630 calendar years (cal yr). The records are not stationary; during the past 2740 yr, drought durations ranged from 20 to 100 yr and intervals between droughts ranged from 80 to 230 yr. Comparison of tree-ring-based reconstructions of climate change for the past 1200 yr from the Sierra Nevada and the El alpais region of northwest New Mexico indicates that severe droughts associated with Anasazi withdrawal from Chaco Canyon at 820 cal yr BP (calendar years before present) and final abandonment of Chaco Canyon, Mesa Verde, and the Kayenta area at 650 cal yr BP may have impacted much of the western United States.During the middle Holocene (informally defined in this paper as extending from 8000 to 3000 cal yr BP), magnetic susceptibility values of sediments deposited in Pyramid Lake's deep basin were much larger than late-Holocene (3000-0 cal yr BP) values, indicating the presence of a shallow lake. In addition, the mean δ 18O value of CaCO3 precipitated between 6500 and 3430 cal yr BP was 1.6‰ less than the mean value of CaCO3 precipitated after 2740 cal yr BP. Numerical calculations indicate that the shift in the δ18O baseline probably resulted from a transition to a wetter (> 30%) and cooler (3-5°C) climate. The existence of a relatively dry and warm middle-Holocene climate in the Truckee River - Pyramid Lake system is generally consistent with archeological, sedimentological, chemical, physical, and biological records from various sites within the Great Basin of the western United States. Two high-resolution Holocene-climate records are now available from the Pyramid and Owens lake basins which suggest that the Holocene was characterized by five climatic intervals. TIC and δ18O records from Owens Lake indicate that the first interval in the early Holocene (11,600-10,000 cal yr BP) was characterized by a drying trend that was interrupted by a brief (200 yr) wet oscillation centered at 10,300 cal yr BP. This was followed by a second early-Holocene interval (10,000-8000 cal yr BP) during which relatively wet conditions prevailed. During the early part of the middle Holocene (8000-6500 cal yr BP), high-amplitude oscillations in TIC in Owens Lake and δ18O in Pyramid Lake indicate the presence of shallow lakes in both basins. During the latter part of the middle Holocene (6500-3800 cal yr BP), drought conditions dominated, Owens Lake desiccated, and Lake Tahoe ceased spilling to the Truckee River, causing Pyramid Lake to decline. At the beginning of the late Holocene (∼3000 cal yr BP), Lake Tahoe rose to its sill level and Pyramid Lake increased in volume. © 2002 Elsevier Science Ltd. All rights reserved.
• Meko, D. M., & Baisan, C. H. (2001). Pilot study of latewood-width of conifers as an indicator of variability of summer rainfall in the North American monsoonregion. International Journal of Climatology, 21(6), 697-708.
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  Abstract: The variability of the North American Monsoon System (NAMS) is important to the precipitation climatology of Mexico and the southwestern United States. Tree-ring studies have been widely applied to climatic reconstruction in western North America, but as yet, have not addressed the NAMS. One reason is the need for highly resolved seasonal dendroclimatic information. Latewood-width, the portion of the annual tree ring laid down late in the growing season, can potentially yield such information. This paper describes a pilot study of the regional summer precipitation signal in latewood-width from a network of five Pseudotsuga menziesii chronologies developed in the heart of the region of NAMS influence in Arizona, USA. Exploratory data analysis reveals that the summer precipitation signal in latewood is strong, but not equally so over the full range of summer precipitation. Scatter in the relationship increases toward higher levels of precipitation. Adjustment for removal of inter-correlation with earlywood-width appears to strengthen the summer precipitation signal in latewood-width. To demonstrate a possible application to climatic reconstruction, the latewood precipitation signal is modelled using a nonlinear model- a binary recursive classification tree (CT) that attempts to classify summers as dry or not dry from threshold values of latewood-width. The model identifies narrow latewood-width as an effective predictor of a dry summer. Of 14 summers classified dry by latewood-width for the period 1868-1992, 13 are actually dry by the instrumental precipitation record. The results suggest that geographical expansion of coverage by latewood-width chronologies and further development of statistical methods may lead to successful reconstruction of variability of the NAMS on century time scales. Copyright © 2001 Royal Meteorological Society.
• Meko, D. M., Therrell, M. D., & Hughes, M. K. (2001). Sacramento River flow reconstructed to A.D. 869 from tree rings. J. of the American Water Resources Association, 37(4), 1029-1040.
• Cook, E. R., Meko, D. M., Stahle, D. W., & Cleaveland, M. K. (1999). Drought reconstructions for the continental United States. Journal of Climate, 12(4), 1145-1163.
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  Abstract: The development of a 2°lat X 3°long grid of summer drought reconstructions for the continental United States estimated from a dense network of annual tree-ring chronologies is described. The drought metric used is the Palmer Drought Severity Index (PDSI). The number of grid points is 154 and the reconstructions cover the common period 1700-1978. In producing this grid, an automated gridpoint regression method called 'point-by-point regression' was developed and tested. In so doing, a near-optimal global solution was found for its implementation. The reconstructions have been thoroughly tested for validity using PDSI data not used in regression modeling. In general, most of the gridpoint estimates of drought pass the verification tests used. In addition, the spatial features of drought in the United States have been faithfully recorded in the reconstructions even though the method of reconstruction is not explicitly spatial in its design. The drought reconstructions show that the 1930s 'Dust Bowl' drought was the most severe such event to strike the United States since 1700. Other more local droughts are also revealed in the regional patterns of drought obtained by rotated principal component analysis. These reconstructions are located on a NOAA Web site at the World Data Center-A in Boulder, Colorado, and can be freely downloaded from there.
• Touchan, R., Meko, D. M., & Hughes, M. K. (1999). A 396 year reconstruction of precipitation in southern Jordan:. Journal of the American Water Resources Association, 35(1), 49-59.
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  Touchan, R., Meko, D.M., and Hughes, M.K., 1999, A 396 year reconstruction of precipitation in southern Jordan: Journal of the American Water Resources Association, v. 35, no. 1, p. 49-59.
• Dettinger, M. D., Cayan, D. R., Diaz, H. F., & Meko, D. M. (1998). North-South precipitation patterns in western North America on interannual-to-decadal timescales. Journal of Climate, 11(12), 3095-3111.
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  Abstract: The overall amount of precipitation deposited along the West Coast and western cordillera of North America from 25°to 55°N varies from year to year, and superimposed on this domain-average variability are varying north-south contrasts on timescales from at least interannual to interdecadal. In order to better understand the north-south precipitation contrasts, their interannual and decadal variations are studied in terms of how much they affect overall precipitation amounts and how they are related to large-scale climatic patterns. Spatial empirical orthogonal functions (EOFs) and spatial moments (domain average, central latitude, and latitudinal spread) of zonally averaged precipitation anomalies along the westernmost parts of North America are analyzed, and each is correlated with global sea level pressure (SLP) and sea surface temperature series, on interannual (defined here as 3-7 yr) and decadal (>7 yr) timescales. The interannual band considered here corresponds to timescales that are particularly strong in tropical climate variations and thus is expected to contain much precipitation variability that is related to El Nino-Southern Oscillation; the decadal scale is defined so as to capture the whole range of long-term climatic variations affecting western North America. Zonal EOFs of the interannual and decadal filtered versions of the zonal-precipitation series are remarkably similar. At both timescales, two leading EOFs describe 1) a north-south seesaw of precipitation pivoting near 40°N and 2) variations in precipitation near 40°N, respectively. The amount of overall precipitation variability is only about 10% of the mean and is largely determined by precipitation variations around 40°-45°N and most consistently influenced by nearby circulation patterns; in this sense, domain-average precipitation is closely related to the second EOF. The central latitude and latitudinal spread of precipitation distributions are strongly influenced by precipitation variations in the southern parts of western North America and are closely related to the first EOF. Central latitude of precipitation moves south (north) with tropical warming (cooling) in association with midlatitude western Pacific SLP variations, on both interannual and decadal timescales. Regional patterns and zonal averages of precipitation-sensitive tree-ring series are used to corroborate these patterns and to extend them into the past and appear to share much long- and short-term information with the instrumentally based zonal precipitation EOFs and moments.
• Cook, E. R., Meko, D. M., & Stockton, C. W. (1997). A new assessment of possible solar and lunar forcing of the bidecadal drought rhythm in the western United States. Journal of Climate, 10(6), 1343-1356.
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  Abstract: A new drought area index (DAI) for the United States has been developed based on a high-quality network of drought reconstructions from tree rings. This DAI is remarkably similar to one developed earlier based on much less data and shows strong evidence for a persistent bidecadal drought rhythm in the western United States since 1700. This rhythm has in the past been associated with possible forcing by the 22-yr Hale solar magnetic cycle and the 18.6-yr lunar nodal tidal cycle. The authors make a new assessment of these possible forcings on DAI using different methods of analysis. In so doing, they confirm most of the previous findings. In particular, there is a reasonably strong statistical association between the bidecadal drought area rhythm and years of Hale solar cycle minima and 18.6-yr lunar tidal maxima. The authors also show that the putative solar and lunar effects appear to be interacting to modulate the drought area rhythm, especially since 1800. These results do not eliminate the possibility that the drought area rhythm is, in fact, internally forced by coupled ocean-atmosphere processes. Recent modeling results suggest that unstable ocean-atmosphere interactions in the North Pacific could be responsible for the drought rhythm as well. However, the results presented here do not easily allow for the rejection of the solar and lunar forcing hypotheses either.
• Meko, D. (1997). Dendroclimatic reconstruction with time varying predictor subsets of tree indices. Journal of Climate, 10(4), 687-696.
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  Abstract: Tree-ring site chronologies, the predictors for most dendroclimatic reconstructions, are assentially mean-value functions with a time varying sample size (number of trees) and sample composition. Because reconstruction models are calibrated and verified on the most recent, best-replicated part of the chronologies, regression and verification statistics can be misleading as indicators of long-term reconstruction accuracy. A new reconstruction method is described that circumvents the use of site chronologies and instead derives predictor variables from indices of individual trees. Separate regression models are estimated and cross validated for various time segments of the tree-ring record, depending on the trees available at the time. This approach allows the reconstruction to extend to the first year covered by any tree in the network and yields direct evaluation of the change in reconstruction accuracy with tree-ring sample composition. The method includes two regression stages. The first is to separately deconvolve the local climate signal for individual trees, and the second is to weight the deconvolved signals into estimates of the climatic variable to be reconstructed. The method is illustrated in an application of precipitation and tree-ring data for the San Pedro River Basin in Southeastern Arizona. Extensions to larger-scale problems and spatial reconstruction are suggested.
• Woodhouse, C. A., & Meko, D. (1997). Number of winter precipitation days reconstructed from southwestern tree rings. Journal of Climate, 10(10), 2663-2669.
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  Abstract: The potential of reconstructing the number of winter precipitation days from tree-rings in the southwestern United States is explored in this study. This variable, an alternative to the measure of total precipitation, has not previously been used in dendroclimatic reconstructions. However, it may be a more meaningful measure of seasonal rainfall and indicator of anomalies in atmospheric circulation features than total precipitation in areas such as the arid Southwest, where the distribution of rainfall is spatially variable. The number of precipitation days in the region encompassing southwestern New Mexico and southeastern Arizona was reconstructed for the time period 1702-1983 from a collection of tree-ring chronologies in this area. Results from this study show that tree-ring chronologies explain 71% of the variance in the regional record of the number of precipitation days. The reconstruction is statistically verified and validated with independent data. Tree-ring chronologies in this region are better able to explain variations in precipitation-day numbers than total precipitation, suggesting that other dendroclimatic studies may benefit from the use of this variable as well.
• Edmondson, J., Friedman, J., Meko, D., Touchan, R., Scott, J., & Edmondson, A. (2014). Dendroclimatic potential of plains cottonwood (Populus deltoides subsp monilifera) from the Northern Great Plains, USA. Tree-Ring Research, 70(1), 21-30.
• Cook, E. R., Briffa, K. R., Meko, D. M., Graybill, D. A., & Funkhouser, G. (1995). The segment length curse' in long tree-ring chronology development for palaeoclimatic studies. Holocene, 5(2), 229-237.
• Meko, D. M., Stockton, C. W., & Boggess, W. R. (1995). Tree-ring record of severe sustained drought. Water Resources Bulletin, 31(5), 789-801.
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  Abstract: Frequent and persistent droughts exacerbate the problems caused by the inherent scarcity of water in the semiarid to arid parts of the southwestern United States. The occurrence of drought is driven by climatic variability, which for years before about the beginning of the 20th century in the Southwest must be inferred from proxy records. As part of a multidisciplinary study of the potential hydrologic impact of severe sustained drought on the Colorado River, the physical basis and limitations of tree rings as indicators of severe sustained drought are reviewed, and tree-ring data are analyzed to delineate a 'worst-case' drought scenario for the Upper Colorado River Basin (UCRB). Runs analysis of a 121-site tree-ring network, 1600-1962, identifies a four-year drought in the 1660s as the longest-duration large-scale drought in the Southwest in the recent tree-ring record. Longer tree-ring records suggest a much longer and more severe drought in 1579-1598. The regression estimate of the mean annual Colorado River flow for this period is 10.95 million acre-feet, or 81 percent of the long-term mean. The estimated flows for the 1500s should be used with caution in impact studies because sample size is small and some reconstructed values are extrapolations.
• Meko, D., & Graybill, D. A. (1995). Tree-ring reconstruction of Upper Gila River discharge. Water Resources Bulletin, 31(4), 605-616.
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  Abstract: Effective planning for use of water resources requires accurate information on hydrologic variability induced by climatic fluctuations. Tree-ring analysis is one method of extending our knowledge of hydrologic variability beyond the relatively short period covered by gaged streamflow records. In this paper, a network of recently developed tree-ring chronologies is used to reconstruct annual river discharge in the upper Gila River drainage in southeastern Arizona and southwestern Arizona since A.D. 1663. The need for data on hydrologic variability for this semi-arid basin is accentuated because water supply is inadequate to meet current demand. A reconstruction based on multiple linear regression (R2=0.66) indicates that 20th century is unusual for clustering of high-discharge years (early 1900s), severity of multiyear drought (1950s), and amplification of low-frequency discharge variations. Periods of low discharge recur at irregular intervals averaging about 20 years. Comparison with other tree-ring reconstructions shows that these low-flow periods are synchronous from the Gila Basin to the southern part of the Upper Colorado River Basin.
• Meko, D. M., Cook, E. R., Stahle, D. W., Stockton, C. W., & Hughes, M. K. (1993). Spatial patterns of tree-growth anomalies in the United States and southeastern Canada. J. of Climate, 6, 1773-1786.
• Meko, D. M., Stockton, C. W., & Blasing, T. J. (1985). Periodicity in tree rings from the Corn Belt.. Science, 229(4711), 381-384.
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  Abstract: Previous tree-ring studies indicated that the total area affected by drought in the western United States has rhythmically expanded and contracted over the past 300 years, with a period near the 18.6-year lunar nodal and 22-year double-sunspot cycles. Recently collected tree-ring data from the US Corn Belt for the years 1680 to 1980 were examined for evidence of either of these cycles on a regional scale. Spectral analysis indicated no periodicity in the eastern part of the Corn Belt, but a significant 18.33-year period in the western part. -from Authors
• Meko, D. M., & Stockton, C. W. (1984). Secular variations in streamflow in the western United States. Journal of climate and applied meteorology, 23(6), 889-897.
• Stockton, C. W., & Meko, D. M. (1983). Drought recurrence in the Great Plains as reconstructed from long-term tree-ring records. Journal of Climate and Applied Meteorology, 22(1), 17-29.
• Meko, D. M., Stockton, C. W., & Boggess, W. R. (1980). A tree-ring reconstruction of drought in southern California. Water Resources Bulletin, 16(4), 594-600.
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  Meko, D.M., Stockton, C.W., and Boggess, W.R., 1980, A tree-ring reconstruction of drought in southern California: Water Resources Bulletin, v. 16, no. 4, p. 594-600.
• Stockton, C. W., & Meko, D. M. (1975). A long-term history of drought occurrence in western United States as inferred from tree rings. Weatherwise, 28(6), 245-249.
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  Stockton, C.W., and Meko, D.M., 1975, A long-term history of drought occurrence in western United States as inferred from tree rings: Weatherwise, v. 28, no. 6, p. 245-249.

Proceedings Publications

• Cook, E. R., Meko, D. M., Stahle, D. W., & Cleaveland, M. K. (1996, November). Tree-ring reconstructions of past drought across the coterminous United States: Tests of a regression method and calibration/verification results. In In Dean, J.S., Meko, D.M., and Swetnam, T.W., eds., Tree rings, environment and humanity, 155-169.
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  Cook, E.R., Meko, D.M., Stahle, D.W., and Cleaveland, M.K., 1996, Tree-ring reconstructions of past drought across the coterminous United States: Tests of a regression method and calibration/verification results, in Dean, J.S., Meko, D.M., and Swetnam, T.W., eds., Tree rings, environment and humanity: Tucson, Arizona, USA, Radiocarbon, p. 155-169.
• Meko, D. (1996, 1996). Statistical challenges to tree-ring reconstruction of climatic time series. In 13TH Conference on probability and statistics in the atmospheric sciences, 22-25.
• Sieg, C. H., Meko, D. M., DeGaetano, A. D., & Ni, W. (1996, November). Dendroclimatic potential in the northern Great Plains. In In Dean, J.S., Meko, D.M., and Swetnam, T.W., eds., Tree rings, environment and humanity, 295-302.
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  Sieg, C.H., Meko, D.M., DeGaetano, A.D., and Ni, W., 1996, Dendroclimatic potential in the northern Great Plains, in Dean, J.S., Meko, D.M., and Swetnam, T.W., eds., Tree rings, environment and humanity; Proceedings of the International Conference, Tucson, Arizona, 17-21 May, 1994: Tucson, Radiocarbon, p. 295-302.
• Mitchell Jr, J. M., Stockton, C. W., & Meko, D. (1979, January). Evidence of a 22-year rhythm of drought in the western United States related to the Hale solar cycle since the 17th century.. In Solar-terrestrial influences on weather and climate. Proc. symposium/workshop, Columbus, Ohio, August 1978, 125-143.
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  Abstract: Families of Drought Area Indices (DAI) have been derived from tree-ring data for the entire U.S. west of the Mississippi River, for each year back to either 1700 or 1600 A.D., depending on the data base used. Three families of DAI are considered in the analysis reported in this paper. The solar control is best described as a modulation of terrestrial drought-inducing mechanisms, such that it alternately encourages and discourages the development of major continental droughts which are set up by evolutionary climatic processes unrelated to solar activity. - Authors

Presentations

• Thaxton, R. D., Meko, D. M., & Panyushkina, I. P. (2022, Summer). The potential for quantitative wood anatomy of dryland riparian trees to improve understanding of historic water availability in the USA Southwest. Frontiers in Hydrology Meeting (AGU). San Juan, Puerto Rico: American Geophysical Union (AGU) and CUAHSI (Consortium of Universities for the Advancement of Hydrologic Science, Inc.).
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  311-05 The potential for quantitative wood anatomy of dryland riparian trees to improve understanding of historic water availability in the USA Southwest Wednesday, 22 June 2022 10:10 - 10:16 Puerto Rico Convention Center - Room 209
• Meko, D., Prusevich, A., Panyushkina, I., Shiklomanov, A., Thaxton, R., Glidden, S., & Lammers, R. (2021, 2021-09-22). TRISH: Online tool for assessment of the hydro-climatic signal in tree-ring chronologies. International Dendrochronological Conference -- RusDendro-2021, September 18-23, 2021. Abakan, Russia (Zoom): Siberian Federal University and Khakasia Technical Institute.
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  Oral presentation in Russian by D. Meko, with help from I. Panyushkina in fielding questions in Russian.
• Shamir, E., Lepley, K., Meko, D., Campbell, R., & Georgakakos, K. (2019, April). High-resolution land surface model to simulate site-specific inter-annual variation of conifers earlywood and latewood ring width. EGU General As- sembly 2019, Vienna, Austria, 7-17 April.. Vienna, Austria: EGU.
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  Oral presentation EGU2019-3195, by Eylon Shamir, in session CL1.38/BG2.41 - Interdisciplinary Tree-Ring Research
• Welsh, C., Smith, D., & Meko, D. (2020, April). Multi-basin tree-ring reconstruction of summer streamflow in northern British Columbia, Canada. AAG Annual Meeting. Denver, CO: American Association of Geographers.
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  Session: Dendrochronology II: Dendrohydrology; Sponsor Groups: Climate Specialty GroupDay: 4/8/2020Start / End Time: 9:35 AM / 10:50 AMRoom: Governors Square 15, Sheraton, Concourse LevelOrganizers: Bethany Coulthard, Rebecca BriceChairs: Bethany CoulthardThe impacts of climate variability and change on streamflow variability are of increasing concern, particularly as human demands on water supplies compete with the needs of natural ecosystems. This study presents multi-century long reconstructions of July-August (summer) streamflow for the Skeena (1599-2016), Nass (1301-2016) and Stikine (1670-2012) rivers that have experienced detrimental low flows in recent decades. A tree-ring network using ring width and maximum latewood density records were investigated for their sensitivity to regional-scale snowpack variability and modelled using a time-nested regression approach incorporating paleoreconstructions of hemispheric climate variability to develop reconstructions of streamflow for three large, snow-influenced drainage basins in northern British Columbia (BC). The results suggest that current drought conditions are a rare event over a multi-century context and the instrumental record does not adequately represent the prehistoric range of variability present in the reconstructions. The distribution of single-year, low flow events show a distinct asynchronous clustering pattern using event analysis, and demonstrates a unique north-south "see-saw" pattern of hydroclimate variability. Multi-decadal comparisons with long-term Gulf of Alaska surface air temperatures (Jan-Sep) support these findings. These results corroborate other studies and suggest the persistence of a more complex interrelationship of moisture availability and transport within the land-atmosphere-ocean system in this region than has been previously reported. This study has attempted to refine and expand the existing understanding of temporal and spatial patterns of streamflow variability and its climate drivers in northern BC.
• Nolin, A. F., Tardif, J. C., Conciatori, F., Meko, D. M., & Bergeron, Y. (2019, 2019-12-12). Multi-centennial spring flood reconstruction using novel application of wood-cell anatomy in Eastern Boreal Canada. AGU Fall Meeting. San Francisco, CA: American Geophysical Union.
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  Nolin, A. F., J. C. Tardif, F. Conciatori, D. M. Meko, and Y. Bergeron (2019), Multi-centennial spring flood reconstruction using novel application of wood-cell anatomy in Eastern Boreal Canada, Oral presentation PP42-02 in session Climate of the Common Era II at 2019 Fall Meeting of American Geophysical Union, San Francisco, 9-13
• Touchan, R., Meko, D. M., Hughes, M. K., Shamir, E., & Lepley, K. (2018, 2018-11-14). Seasonal climate signal in giant sequoia tree rings. Sequoia and Kings Canyon Science Symposium. Three Rivers, California.
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  Session: Paleoclimate Insights for Planning Future Natural Re- sources in California
• Woodhouse, C. A., Meko, D. M., & Bigio, E. (2018, June). Southern California Perfect Drought: How Common?. 10th World Dendro Conference. Thimphu, Bhutan.
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  Oral presentation by Connie Woodhouse on our research for California Department of Water Resources
• Ferrerro, M. E., Meko, D., & Villalba, R. (2017, 2017-11-29). Hydroclimate variability in the subtropics of Argentina and potential for water resources management. International Congress on Climate Change and its Impacts. Huaraz, Peru: Geological Society of Peru.
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  Oral presentation of work I was involved in
• Meko, D., Touchan, R., Lepley, K., Shamir, E., & Graham, R. (2017, 2017-09-05). Tracking mountain snowpack with tree rings and a water balance model. International dendrochronological conference "RusDendro-2017". Barnaul, Russia (Altai State University): Consortium of Russian institutions engaged in dendrochronology.
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  Plenary talk, presented in Russian
• Meko, D., Touchan, R., Lepley, K., Shamir, E., & Graham, R. (2017, 2017-11-29). Tree-ring perspective on changing snowpack regimes in mountain watersheds. International Congress on Climate Change and its Impacts. Huaraz, Peru: Geological Society of Peru.
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  Oral presentation at session co-organized with Eugenia Ferrero.
• Meko, D., Woodhouse, C., & Bigio, E. (2017, 2017-11-01). Paleo hydroclimate reconstructions for Southern California. Winter Outlook Workshop. Scripps Institute of Oceanography: California Department of Water Resources.
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  Invited presentation on result of 2015-2017 tree-ring study being funded by California Department of Water Resources
• Cook, B., Anchukaitis, K. J., Touchan, R., Meko, D. M., & Cook, E. R. (2016, 2016-12-12). Spatiotemporal drought variability in the Mediterranean over the last 900 years. AGU Fall Meeting. San Francisco, California: American Geophysical Union.
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  Invited presentation H14E-01Session: H14E Hydroclimatic Extremes: Drought IProgram: Hydrology
• Touchan, R., Anchukaitis, K. J., Shishov, V. V., Kherchouche, D., Slimani, S., Ilmen, R., Hasnaoui, F., Guibal, F., Camarero, J. J., Sánchez Salguero, R., Piermattei, A., Sesbou, A., Meko, D. M., Cook, B. I., & Sabir, M. (2016, 2016-12-16). Common Era Hydroclimate and Atmospheric Circulation in the Western Mediterranean Basin. AGU Fall Meeting. San Francisco, California: American Geophysical Union.
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  Presentation PP53D-08Session: PP53D Climate of the Common Era IVProgram: Paleoceanography and PaleoclimatologyDrought phenomenon in the Mediterranean Basin, including North Africa and the western Mediterranean, has an impact on all segments of society and all economic sectors. To understand contemporary patterns and causes of drought in these regions, it is necessary to understand natural climate variability over the Common Era. Here, we use a network of tree-ring proxies spanning up to a millennium to understand and reconstruct both large-scale Atlantic circulation changes and regional hydroclimate. Eighty-five chronologies across the region show a variable but coherent response to winter-spring precipitation mediated by geography and topography. Reconstructions using this network of spatiotemporal drought variability as well as a new reconstruction of the North Atlantic Oscillation put the past, present, and future climate variability of the region into a long-term Common Era context.

Poster Presentations

• Gangopadhyay, S., Woodhouse, C. A., McCabe, G. J., Routson, C., & Meko, D. M. (2022, Summer). A 2000-year Streamflow Time Series for the Colorado River at Lees Ferry, AZ. Frontiers in Hydrology Meeting (AGU). San Juan, Puerto Rico: American Geophysical Union (AGU) and CUAHSI (Consortium of Universities for the Advancement of Hydrologic Science, Inc.).
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  Wednesday, 22 June 2022 08:14 - 08:17 Puerto Rico Convention Center - eLightning Theater I
• Meko, D. M., Winitsky, A. G., Biondi, F., & Taylor, A. H. (2022, Summer). Screening Tree-ring Chronologies for Hydrologic Reconstruction with Lagged Regression. Frontiers in Hydrology Meeting (AGU). San Juan, Puerto Rico: American Geophysical Union (AGU) and CUAHSI (Consortium of Universities for the Advancement of Hydrologic Science, Inc.).
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  The full scientific online program is available on the #FIHM22 website. Abstract ID: 1032442 Abstract Title: Screening Tree-ring Chronologies for Hydrologic Reconstruction with Lagged Regression Final Paper Number: 303-05 Presentation Type: eLightning Session Date and Time: Wednesday, 22 June 2022; 08:00 - 09:00 Presentation Length: 08:17 - 08:20 Session Number and Title: 303: Droughts and Floods: Long-Term Context from Tree-Rings for Recent and Projected Extremes I eLightning Location: Puerto Rico Convention Center; eLightning Theater I
• Panyushkina, I. P., Meko, D. M., Shiklomanov, A. I., & Thaxton, R. D. (2022, Summer). Increased winter runoff in Siberia modeled with tree rings as evidence for the recent high rate of permafrost degradation. Frontiers in Hydrology Meeting (AGU). San Juan, Puerto Rico: American Geophysical Union (AGU) and CUAHSI (Consortium of Universities for the Advancement of Hydrologic Science, Inc.).
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  233-114 Increased winter runoff in Siberia modeled with tree rings as evidence for the recent high rate of permafrost degradation Tuesday, 21 June 2022 13:30 - 15:30 Puerto Rico Convention Center - Hall C (Poster Hall)
• Panyushkina, I. P., Thaxton, R. D., & Meko, D. M. (2022, Summer). Modeling Seasonality of River Discharge in Pan-Arctic Watersheds with Ring Width and Tracheid Anatomical Parameters. Frontiers in Hydrology Meeting (AGU). San Juan, Puerto Rico: American Geophysical Union (AGU) and CUAHSI (Consortium of Universities for the Advancement of Hydrologic Science, Inc.).
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  303-03 Modeling Seasonality of River Discharge in Pan-Arctic Watersheds with Ring Width and Tracheid Anatomical Parameters Wednesday, 22 June 2022 08:11 - 08:14 Puerto Rico Convention Center - eLightning Theater I
• Thaxton, R. D., Panyushkina, I. P., Meko, D. M., & von Arx, G. (2022, Summer). How Do Wood Anatomical Traits in Salix Vary in Response to Flooding? A Case Study from the Yenisei River, Siberia. Frontiers in Hydrology Meeting (AGU). San Juan, Puerto Rico: American Geophysical Union (AGU) and CUAHSI (Consortium of Universities for the Advancement of Hydrologic Science, Inc.).
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  303-02 How Do Wood Anatomical Traits in Salix Vary in Response to Flooding? A Case Study from the Yenisei River, Siberia Wednesday, 22 June 2022 08:08 - 08:11 Puerto Rico Convention Center - eLightning Theater I
• Winitsky, A. G., Meko, D. M., Taylor, A. H., & Biondi, F. (2022, Summer). Species Sensitivity to Hydrologic Whiplash in The Tree-Ring Record of the High Sierra Nevada. Frontiers in Hydrology Meeting (AGU). San Juan, Puerto Rico: American Geophysical Union (AGU) and CUAHSI (Consortium of Universities for the Advancement of Hydrologic Science, Inc.).
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  303-06 Species Sensitivity to Hydrologic Whiplash in The Tree-Ring Record of the High Wednesday, 22 June 2022 08:20 - 08:23 Puerto Rico Convention Center - eLightning Theater I
• Woodhouse, C. A., Routson, C., Meko, D. M., Gangopadhyay, S., & McCabe, G. J. (2022, Summer). The Second Century Drought in the Upper Colorado River Basin. Frontiers in Hydrology Meeting (AGU). San Juan, Puerto Rico: American Geophysical Union (AGU) and CUAHSI (Consortium of Universities for the Advancement of Hydrologic Science, Inc.).
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  Presentation 317-01 Wednesday, 22 June 2022 14:30 - 14:33 Online Session - Online Session I
• Meko, D., Biondi, F., & Winitsky, A. (2020, 2020-12-10). Adapting Historical Climate Network precipitation and temperature data for water-balance modeling. AGU Fall Meeting. San Francisco, CA (Zoom): American Geophysical Union.
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  Meko, D. M., Biondi, F., & Winitsky, A. G. (2020). . (eLightning Poster H102-14 (Abstract Id 753067); Session: H102: Modeling the Hydrologic Impacts of Climate Change and Environmental Feedbacks at the Catchment Scale II; 2020 Fall Meeting of American Geophysical Union, 10 December, San Francisco (On Zoom))
• Meko, D., Morino, K., Shamir, E., Edwards, J., Touchan, R., & Campbell, R. (2019, 2019-12-12). Snowpack signal in cell anatomy of Sierra Nevada tree rings. AGU Fall Meeting. San Francisco, CA: American Geophysical Union.
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  Meko, D. M., K. Morino, E. Shamir, J. A. Edwards, R. Touchan, and R. Campbell(2019), Snowpack signal in cell anatomy of sierra nevada treet rings, eLightningPoster B44F-11 (Abstract Id 411062); Session: B44F, New Avenues of MultiproxyDendroecology: Synthesis, Challenges, and Opportunities of High-Resolution TreeRing Research; 2019 Fall Meeting of American Geophysical Union, 9-13 December,San Francisco.
• Touchan, R., Shamir, E., Hughes, M., & Meko, D. (2019, 2019-12-12). New insights on hydroclimate signal in giant sequoia tree-ring growth. AGU Fall Meeting. San Francisco, CA: American Geophysical Union.
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  Touchan, R., E. Shamir, M. K. Hughes, and D. M. Meko (2019), New insights onhydroclimate signal in giant sequoia tree-ring growth, Poster PP43D-1619 in sessionPP43D Climate of the Common Era III Posters; 2019 Fall Meeting of AmericanGeophysical Union, San Francisco, 9-13 December.
• Meko, D. M., Agafonov, L. I., Panyushkina, I. P., & Edwards, J. A. (2018, 2018-12-12). Ob River flood history from tree rings. AGU Fall Meeting. Washington, D.C.: American Geophysical Union.
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  {Poster GC33E-1413 (Abstract Id 411062); Session: Environmental, Socioeconomic and Environmental Changes in Northern Eurasia
• Woodhouse, C. A., Meko, D. M., & Bigio, E. (2018, 2018-02-15). Colorado and Califonia droughts: How common are region-wide droughts?. AAAS Annual Meeting. Austin, Texas: American Association for Advancement of Science.
• Lepley, K., Meko, D., Touchan, R., Shamir, E., & Graham, R. (2017, 2017-12-14). High-elevation Sierra Nevada conifers reveal increasing reliance on snow water with changing climate. AGU Fall Meeting. New Orleans, Louisiana: American Geophysical Union.
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  Poster PA23C-0382
• Shamir, E., Graham, R., Meko, D., Touchan, R., Lepley, K., Kaliff, R., & Georgakakos, K. (2017, 2017-12-14). Tree rings dependence on snowpack and soil water content in the Sierra Nevada Mountains. AGU Fall Meeting. New Orleans, Louisiana: American Geophysical Union.
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  Poster H43C-1660
• Coulthard, B. L., Touchan, R., Meko, D. M., Anchukaitis, K. J., Sivrikaya, F., Attalah, S., Ilmen, R., Aloui, A., Attieh, J., Mitsopoulos, I., Sabir, M., Christou, A., Bozali, N., Ketmen, M., & Stephan, J. (2016, 2016-12-14). Reconstructing Ecosystem-Scale Vegetation Activity Across the Terrestrial Mediterranean using Tree-Ring Width Data. AGU Fall Meeting. San Francisco, California: American Geophysical Union.
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  Poster B33F-0686Session: B33F Remote Sensing to Support Investigations in Plant-Climate Interactions II PostersProgram: Biogeosciences
• Lepley, K. S., Touchan, R., Meko, D. M., Graham, R., & Shamir, E. (2016, 2016-12-12). Conifer Growth Response to Snowpack across an Elevation Gradient in Northern Sierra Nevada Mountains, California. AGU Fall Meeting. San Francisco, California: American Geophysical Union.
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  Poster GC13E-1234:Session: GC13E Natural and Anthropogenic Drivers of Hydroclimatic Change in Western North America II PostersProgram: Global Environmental Change
• Meko, D. M., Agafonov, L. I., & Panyushkina, I. P. (2016, 2016-12-12). Temporal Extension of Discharge Records of Arctic Rivers with Floodplain Tree-Ring Widths. AGU Fall Meeting. San Francisco, California: American Geophysical Union.
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  Poster PP11C-2029:Session: PP11C Polar Hydroclimate in a Paleoclimate Context: Current Understanding and Future Challenges PostersProgram: Paleoceanography and PaleoclimatologyAbstractDischarge of Arctic rivers is critically important to the global climate system, but the shortness of gaged records limits our understanding of the dynamics of such rivers on timescales of decades to centuries. While tree rings have been widely applied to extend discharge records in many parts of the world, applications in the Arctic are limited by the lack of moisture-sensitive tree-ring chronologies. This study explores the discharge signal in temperature-limited growth of Pinus sibirica and Larix sibirica trees along the lower Ob River, Russia. The conceptual model relies on large-scale modification of basin air temperatures by extensive and annually variable flooding of the river, and on a narrow seasonal window of cambial growth coinciding with the season in which high water levels are associated with cool air temperatures. Eleven tree-ring chronologies developed specifically for this study are applied in a regression model to extend the discharge record (8-month average, December-July) of the Ob River at Salekhard back to the early 1700s. The reconstruction model (R2=0.31, 1937-2009 calibration period) is strongly supported by statistics from cross-validation and analysis of residuals. The strength of statistical relationship between tree-ring chronologies and discharge increases with smoothing, such that decadal discharge features may be more robustly captured than interannual fluctuations. Results suggest that gaged discharge data for 1937-2009 underestimate both the variability and persistence of discharge in the last three centuries. The considerable remaining uncertainty in discharge variations inferred from floodplain tree-ring records may possibly be reduced by incorporating information from large-scale contintental networks of tree-ring chronologies in reconstruction models.
• Meko, D. M., Panyushkina, I. P., & Agafonov, L. I. (2015, April). Upper air teleconnections to Ob River flows and tree rings. European Geosciences Union General Assembly. Vienna, Austria: European Geosciences Union.
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  Upper air teleconnections to Ob River flows and tree ringsDavid M. Meko, Irina P. Panyushkina, and Leonid I. AgafonovLaboratory of Tree-Ring Research, The University of Arizona, Tucson, Arizona, USARussian Academy of Sciences, Ural Branch, Institute of Plant and Animal Ecology, Ekaterinburg, RussiaThe Ob River, one of the world’s greatest rivers, with a catchment basin about the size of Western Europe, contributes 12% or more of the annual freshwater inflow to the Arctic Ocean. The input of heat and fresh water is important to the global climate system through effects on sea ice, salinity, and the thermohaline circulation of the ocean. As part of a tree-ring project to obtain multi-century long information on variability of Ob River flows, a network of 18 sites of Pinus, Larix, Populus and Salix has been collected along the Ob in the summers of 2013 and 2014. Analysis of collections processed so far indicates a significant relationship of tree-growth to river discharge. Moderation of the floodplain air temperature regime by flooding appears to be an important driver of the tree-ring response. In unraveling the relationship of tree-growth to river flows, it is important to identify atmospheric circulation features directly linked to observed time series variations of flow and tree growth. In this study we examine statistical links between primary teleconnection modes of Northern Hemisphere upper-air (500 mb) circulation, Ob River flow, and tree-ring chronologies. Annual discharge at the mouth of the Ob River is found to be significantly positively related to the phase of the East Atlantic (EA) pattern, the second prominent mode of low-frequency variability over the North Atlantic. The EA pattern, consisting of a north-south dipole of pressure-anomaly centers spanning the North Atlantic from east to west, is associated with a low-pressure anomaly centered over the Ob River Basin, and with a pattern of positive precipitation anomaly of the same region. The positive correlation of discharge and EA is consistent with these know patterns, and is contrasted with generally negative (though smaller) correlations between EA and tree-ring chronologies. The signs of correlations are consistent with a conceptual model of river influence on tree growth through air temperature. Future work aims at combining the tree-ring samples from living trees and remnant wood to reconstruction to quantitiative reconstruction of annual flow over the past millennium.
• Meko, D. M., Touchan, R., Kherchouche, D., & Slimani, S. (2015, December). Diagnostic value of the errors in dendrohydrologic reconstruction. 2015 Fall Meeting. San Francisco: American Geophysical Union.
• Touchan, R., Kherchouche, D., Anchukaitis, K. J., Oudjehih, B., Touchn, H., Slimani, S., & Meko, D. M. (2015, December). Dendroclimatology and Wheat Production in Algeria. 2015 Fall Meeting. San Francisco: American Geophysical Union.
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  Ramzi Touchan1, Dalila Kherchouche2, Kevin J. Anchukaitis3, Bachir Oudjehih2, Hayat Touchan4, Said Slimani5, and David M. Meko1
• Friedman, J. M., Edmondson, J. R., Meko, D. M., Touchan, R., Griffin, E. R., & Zhou, H. (2014, December). Climate and flow variation revealed in tree rings of riparian cottonwood, western North Dakota,. 2014 Fall Meeting of American Geophysical Union, (Abstract 25958). San Francisco: American Geophysical Union.
• Meko, D. M. (2014, April). Reconstruction of Streamflow from Tree Rings by Nested Local-Regression Models. AAG Annual Meeting. Tampa, Fl: American Association of Geographers.

Others

• Meko, D. M., Woodhouse, C. A., & Bigio, E. (2018, 2018-04-01). Southern California Tree-Ring Study, Final Report. California Department of Water Resources; Final Report. https://water.ca.gov/-/media/DWR-Website/ Web-Pages/Water-Basics/Drought/Files/Publications-And-Reports/ UofAZ-SoCal-tree-ring-report-dec-2017.pdf.
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  Agreement 4600011071
• Meko, D. M., Woodhouse, C. A., & Touchan, R. (2014, August). Klamath/San Joaquin/Sacramento Hydroclimatic Reconstructions from Tree Rings. Final Report to California Department of Water Resources, Agreement 4600008850. http://www.water.ca.gov/waterconditions/docs/tree_ring_report_for_web.pdf
• Meko, D. M. (1981, May). Applications of Box-Jenkins Methods of time-series analysis to reconstruction of drought from tree rings. PhD Dissertation, University of Arizona, Dept of Hydrology and Water Resources.