Jeffrey S Czapla-Myers

Interests

Research

Radiometric calibrationRadiometrySensorsUAVCalibration and validationEarth observationSatellite sensors

Courses

Scholarly Contributions

Books

• Czapla-myers, J. S. (2006).

  Automated Ground-Based Methodology in Support of Vicarious Calibration

  . Tucson, Arizona, USA: The University of Arizona..

Journals/Publications

• Arnold, G. T., Bosch, J. V., Bruegge, C. J., Czapla-myers, J. S., Dominguez, R. A., Helmlinger, M. C., Thompson, D. R., & Wenny, B. N. (2021).

  Vicarious Calibration of eMAS, AirMSPI, and AVIRIS Sensors During FIREX-AQ

  . IEEE Transactions on Geoscience and Remote Sensing, 1-12. doi:10.1109/tgrs.2021.3066997
• Czapla-Myers, J., Thome, K., & Wenny, B. N. (2021).

  Evaluation of vicarious calibration for airborne sensors using RadCalNet

  . Journal of Applied Remote Sensing, 15(03). doi:10.1117/1.jrs.15.034501
• Tsuchida, S., Yamamoto, H., Kouyama, T., Obata, K., Sakuma, F., Tachikawa, T., Kamei, A., Arai, K., Czapla-Myers, J. S., Biggar, S. F., & Thome, K. J. (2020). Radiometric Degradation Curves for the ASTER VNIR Processing Using Vicarious and Lunar Calibrations.
• Wenny, B., Thome, K., & Czapla-Myers, J. (2020). Evaluation of vicarious calibration for airborne sensors using RadCalnet.
• Bouvet, M., Thome, K., Berthelot, B., Bialek, A., Czapla-Myers, J., Fox, N. P., Goryl, P., Henry, P., Ma, L., Marcq, S., Meygret, A., Wenny, B. N., & Woolliams, E. R. (2019). RadCalNet: A Radiometric Calibration Network for Earth Observing Imagers Operating in the Visible to Shortwave Infrared Spectral Range.
• Lamquin, N., Woolliams, E., Bruniquel, V., Gascon, F., Gorroño, J., Govaerts, Y., Leroy, V., Lonjou, V., Alhammoud, B., Barsi, J. A., Czapla-Myers, J. S., McCorkel, J., Helder, D., Lafrance, B., Clerc, S., & Holben, B. N. (2019). An inter-comparison exercise of Sentinel-2 radiometric validations assessed by independent expert groups.
• Alhammoud, B., Barsi, J. A., Czapla-Myers, J., Gascon, F., Haque, M. O., Kaewmanee, M., Leigh, L., & Markham, B. L. (2018).

  Sentinel-2A MSI and Landsat-8 OLI radiometric cross comparison over desert sites

  . European Journal of Remote Sensing, 51(1), 822-837. doi:10.1080/22797254.2018.1507613
• Barsi, J. A., Alhammoud, B., Czapla-Myers, J., Gascon, F., Haque, M. O., Kaewmanee, M., Leigh, L., & Markham, B. L. (2018). Sentinel-2A MSI and Landsat-8 OLI radiometric cross comparison over desert sites.
• Ong, C., Thome, K., Heiden, U., Czapla-Myers, J. .., & Mueller, A. (2018). Reflectance-Based Imaging Spectrometer Error Budget Field Practicum at the Railroad Valley Test Site, Nevada [Technical Committees].
• Thome, K., Wenny, B., Anderson, N., McCorkel, J., Czapla-Myers, J., & Biggar, S. (2018). Ultra-portable field transfer radiometer for vicarious calibration of earth imaging sensors.
• Anderson, N., Biggar, S., Czapla-Myers, J., & McCorkel, J. (2017).

  Earth-observing satellite intercomparison using the Radiometric Calibration Test Site at Railroad Valley

  . Journal of Applied Remote Sensing, 12(01), 1. doi:10.1117/1.jrs.12.012004
• Czapla-Myers, J., McCorkel, J., Anderson, N., & Biggar, S. (2017). Earth-observing satellite intercomparison using the Radiometric Calibration Test Site at Railroad Valley.
• Barsi, J. A., Czapla-myers, J. S., Haque, O., Helder, D. L., Hook, S. J., Markham, B. L., & Schott, J. R. (2016).

  Landsat-7 ETM+ Radiometric Calibration Status.

  . Proceedings of SPIE--the International Society for Optical Engineering, 9972. doi:10.1117/12.2238625
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  Now in its 17th year of operation, the Enhanced Thematic Mapper + (ETM+), on board the Landsat-7 satellite, continues to systematically acquire imagery of the Earth to add to the 40+ year archive of Landsat data. Characterization of the ETM+ on-orbit radiometric performance has been on-going since its launch in 1999. The radiometric calibration of the reflective bands is still monitored using on-board calibration devices, though the Pseudo-Invariant Calibration Sites (PICS) method has proven to be an effect tool as well. The calibration gains were updated in April 2013 based primarily on PICS results, which corrected for a change of as much as -0.2%/year degradation in the worst case bands. A new comparison with the SADE database of PICS results indicates no additional degradation in the updated calibration. PICS data are still being tracked though the recent trends are not well understood. The thermal band calibration was updated last in October 2013 based on a continued calibration effort by NASA/Jet Propulsion Lab and Rochester Institute of Technology. The update accounted for a 0.31 W/m2 sr μm bias error. The updated lifetime trend is now stable to within +/- 0.4K.
• Czapla-myers, J. S., Mccorkel, J., Ong, L., & Thome, K. (2016).

  Validation of EO-1 Hyperion and Advanced Land Imager Using the Radiometric Calibration Test Site at Railroad Valley, Nevada

  . IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 9(2), 816-826. doi:10.1109/jstars.2015.2463101
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  The Earth-Observing One (EO-1) satellite was launched in 2000. Radiometric calibration of Hyperion and the Advanced Land Imager (ALI) has been performed throughout the mission lifetime using various techniques that include ground-based vicarious calibration, pseudo-invariant calibration sites, and also the moon. The EO-1 mission is nearing its useful lifetime, and this work seeks to validate the radiometric calibration of Hyperion and ALI from 2013 until the satellite is decommissioned. Hyperion and ALI have been routinely collecting data at the automated Radiometric Calibration Test Site [RadCaTS/Railroad Valley (RRV)] since launch. In support of this study, the frequency of the acquisitions at RadCaTS has been significantly increased since 2013, which provides an opportunity to analyze the radiometric stability and accuracy during the final stages of the EO-1 mission. The analysis of Hyperion and ALI is performed using a suite of ground instrumentation that measures the atmosphere and surface throughout the day. The final product is an estimate of the top-of-atmosphere (TOA) spectral radiance, which is compared to Hyperion and ALI radiances. The results show that Hyperion agrees with the RadCaTS predictions to within 5% in the visible and near-infrared (VNIR) and to within 10% in the shortwave infrared (SWIR). The 2013–2014 ALI results show agreement to within 6% in the VNIR and 7.5% in the SWIR bands. A cross-comparison between ALI and the Operational Land Imager (OLI) using RadCaTS as a transfer source shows agreement of 3%–6% during the period of 2013–2014.
• Anderson, N., Biggar, S. F., Czapla-myers, J. S., & Thome, K. (2015).

  Design of an ultra-portable field transfer radiometer supporting automated vicarious calibration

  . Proceedings of SPIE, 9607. doi:10.1117/12.2186894
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  The University of Arizona Remote Sensing Group (RSG) began outfitting the radiometric calibration test site (RadCaTS) at Railroad Valley Nevada in 2004 for automated vicarious calibration of Earth-observing sensors. RadCaTS was upgraded to use RSG custom 8-band ground viewing radiometers (GVRs) beginning in 2011 and currently four GVRs are deployed providing an average reflectance for the test site. This measurement of ground reflectance is the most critical component of vicarious calibration using the reflectance-based method. In order to ensure the quality of these measurements, RSG has been exploring more efficient and accurate methods of on-site calibration evaluation. This work describes the design of, and initial results from, a small portable transfer radiometer for the purpose of GVR calibration validation on site. Prior to deployment, RSG uses high accuracy laboratory calibration methods in order to provide radiance calibrations with low uncertainties for each GVR. After deployment, a solar radiation based calibration has typically been used. The method is highly dependent on a clear, stable atmosphere, requires at least two people to perform, is time consuming in post processing, and is dependent on several large pieces of equipment. In order to provide more regular and more accurate calibration monitoring, the small portable transfer radiometer is designed for quick, one-person operation and on-site field calibration comparison results. The radiometer is also suited for laboratory calibration use and thus could be used as a transfer radiometer calibration standard for ground viewing radiometers of a RadCalNet site.
• Czapla-Myers, J. .., Ong, L., Thome, K., & McCorkel, J. (2015). Validation of EO-1 Hyperion and Advanced Land Imager Using the Radiometric Calibration Test Site at Railroad Valley, Nevada.
• Czapla-Myers, J., McCorkel, J., Anderson, N., Thome, K., Biggar, S., Helder, D., Aaron, D., Leigh, L., & Mishra, N. (2015). The Ground-Based Absolute Radiometric Calibration of Landsat 8 OLI.
• Thome, K., Czapla-myers, J. S., Mccorkel, J., Thome, K., & Wenny, B. N. (2015).

  Online resource for Earth-observing satellite sensor calibration

  . Proceedings of SPIE, 9607. doi:10.1117/12.2188741
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  The Radiometric Calibration Test Site (RadCaTS) at Railroad Valley Playa, Nevada is being developed by the University of Arizona to enable improved accuracy and consistency for airborne and satellite sensor calibration. Primary instrumentation at the site consists of ground-viewing radiometers, a sun photometer, and a meteorological station. Measurements made by these instruments are used to calculate surface reflectance, atmospheric properties and a prediction for top-of-atmosphere reflectance and radiance. This work will leverage research for RadCaTS, and describe the requirements for an online database, associated data formats and quality control, and processing levels.
• Anderson, N., Biggar, S. F., Czapla-myers, J. S., & Thome, K. (2014).

  The absolute radiometric calibration of Terra imaging sensors: MODIS, MISR, and ASTER

  . Proceedings of SPIE, 9218. doi:10.1117/12.2062529
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  The Terra spacecraft contains five Earth-observation instruments, three of which are multispectral imaging sensors that complement each other in spectral and spatial coverage. The Moderate Resolution Imaging Spectroradiometer (MODIS) has 36 channels ranging from 0.4–14.4 μm, with spatial resolutions of 250, 500, and 1000 m. The Multi-angle Imaging SpectroRadiometer (MISR) uses individual imaging sensors to view the earth at nine discreet angles. Each radiometer has four channels in the visible and near infrared (VNIR), and the nadir-viewing camera has a spatial resolution of 275 m. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) was designed with fourteen bands ranging from 0.5–11.6 μm. It is the high-resolution sensor on Terra, with a spatial resolution of 15 m in the VNIR, and 30 m in the shortwave infrared (SWIR). This work describes the vicarious techniques used to perform the absolute radiometric calibration of MODIS, MISR, and ASTER in the solar-reflective region (0.4–2.5 μm). It includes the reflectance-based approach, which uses ground-based personnel to make in situ measurements during the time of overpass. It also includes more recent results that were obtained using the University of Arizona’s automated Radiometric Calibration Test Site (RadCaTS) at Railroad Valley, Nevada. In addition to the absolute radiometric calibration of Terra sensors, RadCaTS is used to perform the cross comparison of MODIS, MISR, and ASTER with Landsat 7 ETM+ and Landsat 8 OLI.
• Anderson, N., Biggar, S. F., Czapla-myers, J. S., & Thome, K. (2014).

  The absolute radiometric calibration of the Landsat 8 Operational Land Imager using the reflectance-based approach and the Radiometric Calibration Test Site (RadCaTS)

  . Proceedings of SPIE, 9218. doi:10.1117/12.2063321
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  Landsat 8 was launched on 11 February 2013 as the newest platform in the Landsat program. It contains two Earthobserving instruments, one of which is the Operational Land Imager (OLI). OLI includes an onboard radiometric calibration system that is used to monitor changes in its responsivity throughout the mission lifetime, and it consists of Spectralon solar diffuser panels as well as tungsten lamp assemblies. External techniques are used to monitor both OLI and its calibration system, and they include lunar views, side slither maneuvers of the satellite, and ground-based vicarious calibration. This work presents the absolute radiometric calibration results for Landsat 8 OLI that were obtained using two ground-based measurement techniques. The first is the reflectance-based approach, where measurements of atmospheric and surface properties are made during a Landsat 8 overpass, and it requires personnel to be on site during the time of measurement. The second uses the Radiometric Calibration Test Site (RadCaTS), which was developed by the Remote Sensing Group in the College of Optical Sciences at the University of Arizona so that radiometric calibration data can be collected without the requirement of on-site personnel. It allows more data to be collected annually, which increases the temporal sampling of trending results.
• Markham, B., Barsi, J., Kvaran, G., Ong, L., Kaita, E., Biggar, S., Czapla-Myers, J., Mishra, N., & Helder, D. (2014). Landsat-8 Operational Land Imager Radiometric Calibration and Stability.
• Anderson, N. J., & Czapla-Myers, J. S. (2013). Ground viewing radiometer characterization, implementation and calibration applications - A summary after two years of field deployment. Proceedings of SPIE - The International Society for Optical Engineering, 8866.
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  Abstract: In 2011, three improved ground-viewing radiometers (GVRs) were built and deployed to support the Radiometric Calibration Test Site (RadCaTS) developed by the Remote Sensing Group (RSG) at the University of Arizona. The GVRs are filter-based radiometers with eight spectral channels covering a wavelength range of 400-1550 nm. They are automated, field-deployable instruments capable of long-term, standalone operation. The radiometers are temperaturecontrolled and designed for greater stability and lower noise than their light emitting diode (LED) based predecessors. This work describes the deployment period of these radiometers with particular attention paid to the in-field performance, reliability, and results from these instruments. Using other RadCaTS inputs including meteorological station data and Aerosol Robotic Network (AERONET) Cimel sun photometer data, select vicarious calibration results are presented. With these results, an assessment of the calibration applications of the RadCaTS during new GVR deployment is discussed. In addition, GVR calibration and characterization results, including solar radiation based calibration (SRBC), are presented as another means of assessing the performance of the radiometers over deployment periods. © 2013 SPIE.
• Anderson, N., Czapla-Myers, J., Leisso, N., Biggar, S., Burkhart, C., Kingston, R., & Thome, K. (2013). Design and calibration of field deployable ground-viewing radiometers.
• Anderson, N., Czapla-Myers, J., Leisso, N., Biggar, S., Burkhart, C., Kingston, R., & Thome, K. (2013). Design and calibration of field deployable ground-viewing radiometers. Applied Optics, 52(2), 231-240.
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  PMID: 23314640;Abstract: Three improved ground-viewing radiometers were built to support the Radiometric Calibration Test Site (RadCaTS) developed by the Remote Sensing Group (RSG) at the University of Arizona. Improved over previous light-emitting diode based versions, these filter-based radiometers employ seven silicon detectors and one InGaAs detector covering a wavelength range of 400-1550 nm. They are temperature controlled and designed for greater stability and lower noise. The radiometer systems show signal-to-noise ratios of greater than 1000 for all eight channels at typical field calibration signal levels. Predeployment laboratory radiance calibrations using a 1 m spherical integrating source compare well with in situ field calibrations using the solar radiation based calibration method; all bands are within ±2.7% for the case tested. © 2013 Optical Society of America.
• Czapla-Myers, J. S., Anderson, N. J., & Biggar, S. F. (2013). Early ground-based vicarious calibration results for landsat 8 OLI. Proceedings of SPIE - The International Society for Optical Engineering, 8866.
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  Abstract: The Operational Land Imager (OLI) is one of two instruments onboard the Landsat 8 platform, which was launched on 11 February 2013 from Vandenberg Air Force Base in California. The multispectral bands of OLI retain the 30-m spatial resolution of Landsat 5 TM and Landsat 7 ETM+, but improvements to the system include 12-bit radiometric resolution, eight multispectral bands in the VNIR and SWIR spectral regions, and one panchromatic band. The earlier TM and ETM+ sensors use a whiskbroom configuration, while OLI uses a pushbroom configuration, which allows it to have a higher signal-to-noise ratio than previous Landsat instruments. This also creates challenges in radiometric calibration due to the large number of detectors on the 14 focal plane modules. Long-term data continuity is a crucial component of the 40-year Landsat series of satellites, and ground-based vicarious calibration has played an important role in ensuring that these sensors remain on the same radiometric scale. This work presents the early ground-based in-flight radiometric calibration of OLI, which was determined using the traditional and well-understood reflectance-based approach, as well as the Radiometric Calibration Test Site (RadCaTS), which is an automated suite of instruments located at Railroad Valley, Nevada. © 2013 SPIE.
• Thome, K., McCorkel, J., & Czapla-Myers, J. (2013). In-situ transfer standard and coincident-view intercomparisons for sensor cross-calibration. IEEE Transactions on Geoscience and Remote Sensing, 51(3), 1088-1097.
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  Abstract: There exist numerous methods for accomplishing on-orbit calibration. Methods include the reflectance-based approach relying on measurements of surface and atmospheric properties at the time of a sensor overpass as well as invariant scene approaches relying on knowledge of the temporal characteristics of the site. The current work examines typical cross-calibration methods and discusses the expected uncertainties of the methods. Data from the Advanced Land Imager (ALI), Advanced Spaceborne Thermal Emission and Reflection and Radiometer (ASTER), Enhanced Thematic Mapper Plus (ETM+), Moderate Resolution Imaging Spectroradiometer (MODIS), and Thematic Mapper (TM) are used to demonstrate the limits of relative sensor-to-sensor calibration as applied to current sensors while Landsat-5 TM and Landsat-7 ETM+ are used to evaluate the limits of in situ site characterizations for SI-traceable cross calibration. The current work examines the difficulties in trending of results from cross-calibration approaches taking into account sampling issues, site-to-site variability, and accuracy of the method. Special attention is given to the differences caused in the cross-comparison of sensors in radiance space as opposed to reflectance space. The results show that cross calibrations with absolute uncertainties < 1.5% (1σ) are currently achievable even for sensors without coincident views. © 2012 IEEE.
• Thome, K., McCorkel, J., & Czapla-Myers, J. .. (2013). In-Situ Transfer Standard and Coincident-View Intercomparisons for Sensor Cross-Calibration.
• Anderson, N. J., Biggar, S. F., Czapla-myers, J. S., & Leisso, N. P. (2012).

  On-orbit radiometric calibration of Earth-observing sensors using the Radiometric Calibration Test Site (RadCaTS)

  . Proceedings of SPIE, 8390. doi:10.1117/12.918614
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  Vicarious techniques are used to provide supplemental radiometric calibration data for sensors with onboard calibration systems, and are increasingly important for sensors without onboard calibration systems. The Radiometric Calibration Test Site (RadCaTS) is located at Railroad Valley, Nevada. It is a facility that was developed with the goal of increasing the amount of ground-based radiometric calibration data that are collected annually while maintaining the current level of radiometric accuracy produced by traditional manned field campaigns. RadCaTS is based on the reflectance-based approach, and currently consists of a Cimel sun photometer to measure the atmosphere, a weather station to monitor meteorological conditions, and ground-viewing radiometers (GVRs) that are used the determine the surface reflectance throughout the 1 × 1-km area. The data from these instruments are used in MODTRAN5 to determine the at-sensor spectral radiance at the time of overpass. This work describes the RadCaTS concept, the instruments used to obtain the data, and the processing method used to determine the surface reflectance and top-of-atmosphere spectral radiance. A discussion on the design and calibration of three new eight-channel GVRs is introduced, and the surface reflectance retrievals are compared to in situ measurements. Radiometric calibration results determined using RadCaTS are compared to Landsat 7 ETM+, MODIS, and MISR. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
• Forgione, J. B., Grose, J. R., Myers, J. S., Sorenson, C. E., & Vogler, R. G. (2012). The EIP: A standard experimenter interface panel for NASA airborne science. Proceedings of SPIE - The International Society for Optical Engineering, 8516.
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  Abstract: NASA operates a fleet of piloted and UAV aircraft to perform a variety of Earth Science and emergency observation. NASA's recent move toward sensor-web mission architectures requires a corresponding upgrade to its payload systems. NASA Airborne Science payloads will now interface to a new standard Experimenter Interface Panel (EIP), presented here. This discussion will cover the standard interface from the payload perspective. Details are provided on payload interface, cockpit control (for manned aircraft), technical design, network physical layer, qualification, and maintenance. Analyses are provided to support high-altitude design 'rules of thumb' and design decisions. © 2012 SPIE.
• Helder, D., Thome, K., Aaron, D., Leigh, L., Czapla-Myers, J., Leisso, N., Biggar, S., & Anderson, N. (2012). Recent surface reflectance measurement campaigns with emphasis on best practices, SI traceability and uncertainty estimation.
• Helder, D., Thome, K., Aaron, D., Leigh, L., Czapla-Myers, J., Leisso, N., Biggar, S., & Anderson, N. (2012). Recent surface reflectance measurement campaigns with emphasis on best practices, SI traceability and uncertainty estimation. Metrologia, 49(2), S21-S28.
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  Abstract: A significant problem facing the optical satellite calibration community is limited knowledge of the uncertainties associated with fundamental measurements, such as surface reflectance, used to derive satellite radiometric calibration estimates. In addition, it is difficult to compare the capabilities of calibration teams around the globe, which leads to differences in the estimated calibration of optical satellite sensors. This paper reports on two recent field campaigns that were designed to isolate common uncertainties within and across calibration groups, particularly with respect to ground-based surface reflectance measurements. Initial results from these efforts suggest the uncertainties can be as low as 1.5% to 2.5%. In addition, methods for improving the cross-comparison of calibration teams are suggested that can potentially reduce the differences in the calibration estimates of optical satellite sensors. © 2012 BIPM & IOP Publishing Ltd.
• Markham, B. L., Haque, M. O., Barsi, J. A., Micijevic, E., Helder, D. L., Thome, K. J., Aaron, D., & Czapla-Myers, J. S. (2012). Landsat-7 ETM+: 12 Years On-Orbit Reflective-Band Radiometric Performance.
• Markham, B. L., Haque, M. O., Barsi, J. A., Micijevic, E., Helder, D. L., Thome, K. J., Aaron, D., & Czapla-Myers, J. S. (2012). Landsat-7 ETM+: 12 years on-orbit reflective-band radiometric performance. IEEE Transactions on Geoscience and Remote Sensing, 50(5 PART 2), 2056-2062.
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  Abstract: The Landsat-7 ETM+ sensor has been operating on orbit for more than 12 years, and characterizations of its performance have been ongoing over this period. In general, the radiometric performance of the instrument has been remarkably stable: 1) noise performance has degraded by 2% or less overall, with a few detectors displaying step changes in noise of 2% or less; 2) coherent noise frequencies and magnitudes have generally been stable, though the within-scan amplitude variation of the 20 kHz noise in bands 1 and 8 disappeared with the failure of the scan line corrector and a new similar frequency noise (now about 18 kHz) has appeared in two detectors in band 5 and increased in magnitude with time; 3) bias stability has been better than 0.25 DN out of a normal value of 15 DN in high gain; 4) relative gains, the differences in response between the detectors in the band, have generally changed by 0.1% or less over the mission, with the exception of a few detectors with a step response change of 1% or less; and 5) gain stability averaged across all detectors in a band, which is related to the stability of the absolute calibration, has been more stable than the techniques used to measure it. Due to the inability to confirm changes in the gain (beyond a few detectors that have been corrected back to the band average), ETM+ reflective band data continues to be calibrated with the prelaunch measured gains. In the worst case, some bands may have changed as much as 2% in uncompensated absolute calibration over the 12 years. © 2012 IEEE.
• Ambrosia, V., Myers, J., & Hildum, E. (2011). NASA's autonomous modular scanner (AMS) - Wildfire sensor: Improving wildfire observations from airborne platforms. 34th International Symposium on Remote Sensing of Environment - The GEOSS Era: Towards Operational Environmental Monitoring.
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  Abstract: The NASA Autonomous Modular Scanner (AMS) - Wildfire sensor is an airborne, 16-band line scanner with channels in the VIS-IR-MIR-TIR spectral region. Four AMS thermal channels replicate the spectral bandpass region of two of the proposed NPOESS VIIRS channels and allow improved discrimination of wildfire conditions. The AMS has operated on a range of manned and unmanned aircraft, including the NASA Ikhana UAS. On-board processors allow near-real-time Level 2 products to be derived from the spectral data and sent through a satellite link to investigators on the ground. The AMSWildfire instrument has been flown extensively in the western U.S. since 2006, supporting disaster managers with real-time fire products that define hot-spots, active fire, smoldering and post-fire conditions. The AMS has supported satellite calibration and validation efforts with collections over wildfire events simultaneously with MODIS data collections during campaigns in 2007-2010. These measurements have led to improved understanding of the satellite observations and allowed a renewed focus on the AMS sensor as an instrument capable of deriving critical fire parameters to allow improved extrapolation of wildfire thermal properties. With high spatial, temporal and radiometric measurement capabilities of the AMS instrument, improved discrimination of fire properties can be made. The "lingering" capabilities afforded by airborne platforms, allow temporal observations of fire properties, rather than the single observations provided by satellite systems. The AMS operations, successful missions, and plans for future use to support both the fire science community and the disaster management community will be highlighted.
• Czapla-Myers, J. .., Thome, K., & Leisso, N. (2011). Radiometric calibration of earth-observing sensors using an automated test site at Railroad Valley, Nevada.
• Ellis, T. A., Myers, J., Grant, P., Platnick, S., Guerin, D. C., Fisher, J., Song, K., Kimchi, J., Kilmer, L., LaPorte, D. D., & Moeller, C. C. (2011). The NASA enhanced MODIS airborne simulator. Proceedings of SPIE - The International Society for Optical Engineering, 8153.
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  Abstract: The new NASA Enhanced MODIS Airborne Simulator (eMAS) is based on the legacy MAS system, which has been used extensively in support of the NASA Earth Observing System program since 1995. eMAS consists of two separate instruments designed to fly together on the NASA ER-2 and Global Hawk high altitude aircraft. The eMAS-IR instrument is an upgraded version of the legacy MAS line-scanning spectrometer, with 38 spectral bands in the wavelength range from 0.47 to 14.1 μm. The original LN2-cooled MAS MWIR and LWIR spectrometers are replaced with a single vacuum-sealed, Stirling-cooled assembly, having a single MWIR and twelve LWIR bands. This spectrometer module contains a cold optical bench where both dispersive optics and detector arrays are maintained at cryogenic temperatures to reduce infrared background noise, and ensure spectral stability during high altitude airborne operations. The EMAS-HS instrument is a stand-alone push-broom imaging spectrometer, with 202 contiguous spectral bands in the wavelength range from 0.38 to 2.40 μm. It consists of two Offner spectrometers, mated to a 4-mirror anastigmatic telescope. The system has a single slit, and uses a dichroic beam-splitter to divide the incoming energy between VNIR and SWIR focal plane arrays. It will be synchronized and bore-sighted with the IR line-scanner, and includes an active source for monitoring calibration stability. eMAS is intended to support future satellite missions including the Hyperspectral Infrared Imager ( HyspIRI,) the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP,) and the follow-on Joint Polar Satellite System (JPSS.) © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
• Leisso, N., & Czapla-Myers, J. (2011). Comparison of diffuse sky irradiance calculation methods and effect on surface reflectance retrieval from an automated radiometric calibration test site. Proceedings of SPIE - The International Society for Optical Engineering, 8153.
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  Abstract: The Remote Sensing Group (RSG) at the University of Arizona is currently refining an automated system for the absolute radiometric calibration of earth-observing sensors. The Radiometric Calibration Test Site (RadCaTS) relies on semi-permanent instrumentation at the Railroad Valley (RRV) test site to collect data from which surface reflectance and an atmospheric characterization is determined. Multispectral surface reflectance is determined from calibrated ground viewing radiometers and assimilated to determine the hyperspectral reflectance used in radiative transfer calculations. The reflectance retrieval algorithm relies on an accurate determination of the diffuse sky irradiance for the time of interest. Currently, diffuse sky irradiance is modeled using the atmospheric characterization as input into MODTRAN5. This work investigates the accuracy of the diffuse sky modeling by comparing modeled results to measurements made at the test site. Diffuse sky irradiance from several alternative methods are also presented. Surface reflectance is computed and compared to in-situ measurements taken with a portable spectoradiometer. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
• Naughton, D., Brunn, A., Czapla-Myers, J., Douglass, S., Thiele, M., Weichelt, H., & Oxfort, M. (2011). Absolute radiometric calibration of the RapidEye multispectral imager using the reflectance-based vicarious calibration method. APPRES, 5(1), 053544-053544-23.
• Naughton, D., Brunn, A., Czapla-Myers, J., Douglass, S., Thiele, M., Weichelt, H., & Oxfort, M. (2011). Absolute radiometric calibration of the RapidEye multispectral imager using the reflectance-based vicarious calibration method. Journal of Applied Remote Sensing, 5(1).
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  Abstract: RapidEye AG is a commercial provider of geospatial information products and customized solutions derived from Earth observation image data. The source of the data is the RapidEye constellation consisting of five low-earth-orbit imaging satellites. We describe the rationale, methods, and results of a reflectance-based vicarious calibration campaign that was conducted between April 2009 and May 2010 at Railroad Valley Playa and Ivanpah Playa to determine the on-orbit radiometric accuracy of the RapidEye sensor. In situ surface spectral reflectance measurements of known ground targets and an assessment of the atmospheric conditions above the sites were taken during spacecraft overpasses. The ground data are used as input to a radiative transfer code to compute a band-specific top-of-atmosphere spectral radiance. A comparison of these predicted values based on absolute physical data to the measured at-sensor spectral radiance provide the absolute calibration of the sensor. Initial assessments show that the RapidEye sensor response is within 8% of the predicted values. Outcomes from this campaign are then used to update the calibration parameters in the ground segment processing system. Subsequent verification events confirmed that the measured RapidEye response improved to within 4% of the predictions based on the vicarious calibration method. © 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).
• Wang, Y., Czapla-Myers, J. .., Lyapustin, A., Thome, K., & Dutton, E. G. (2011). AERONET-based surface reflectance validation network (ASRVN) data evaluation: Case study for railroad valley calibration site.
• Wang, Y., Czapla-Myers, J., Lyapustin, A., Thome, K., & Dutton, E. G. (2011). AERONET-based surface reflectance validation network (ASRVN) data evaluation: Case study for railroad valley calibration site. Remote Sensing of Environment, 115(10), 2710-2717.
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  Abstract: The AERONET-based Surface Reflectance Validation Network (ASRVN) is an operational processing system developed for validation of satellite derived surface reflectance products at regional and global scales. The ASRVN receives 50×50km2 subsets of MODIS data centered at AERONET sites along with AERONET aerosol and water vapor data, and performs an atmospheric correction. The ASRVN produces surface bidirectional reflectance factor (BRF), albedo, parameters of the Ross-Thick Li-Sparse (RTLS) BRF model, as well as Hemispherical-Directional Reflectance Factor (HDRF), which is required for comparison with the ground-based measurements. This paper presents a comparison of ASRVN HDRF with the ground-based HDRF measurements collected during 2001-2008 over a bright calibration Railroad Valley, Nevada site as part of the MODIS land validation program. The ground measurements were conducted by the Remote Sensing Group (RSG) at the University of Arizona using an ASD spectrometer. The study reveals a good agreement between ASRVN and RSG HDRF for both MODIS Terra and Aqua with rmse~0.01-0.025 in the 500m MODIS land bands B1-B7. Obtained rmse is below uncertainties due to the spatial and seasonal variability of the bright calibration 1km2 area. While two MODIS instruments have a similar rmse in the visible bands, MODIS Aqua has a better agreement (lower rmse) with the ground data than MODIS Terra at wavelengths 0.87-2.1μm. An independent overall good agreement of two MODIS instruments with the ground data indicates that the relative calibration of MODIS Terra and Aqua at medium-to-bright reflectance levels for the stated time period is significantly better than uncertainties of the ASRVN and ground data. © 2011 Elsevier Inc.
• Czapla-Myers, J. S., & Leisso, N. P. (2010). Recent results from the Radiometric Calibration Test Site (RadCaTS) at Railroad Valley, Nevada. Proceedings of SPIE - The International Society for Optical Engineering, 7807.
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  Abstract: The Radiometric Calibration Test Site (RadCaTS) is an automated approach to ground-based vicarious calibration that does not require on-site personnel during the overpass of an airborne or spaceborne sensor. The concept originates as an attempt to increase the amount of ground-based data that are collected throughout the year. All-weather instruments are used to measure atmospheric and surface conditions. The data are used in an automated processing scheme to produce top-of-atmosphere spectral radiance, which are then compared to the sensor under test. RadCaTS has been located at Railroad Valley, Nevada, since 2004, but the concept is applicable to any site that is suitable for vicarious calibration. Railroad Valley was chosen to test the RadCaTS concept because it has been used by the Remote Sensing Group (RSG) for over 15 years and is well understood. This work describes the RadCaTS automated concept, and outlines the automated processing scheme that is used to determine the surface reflectance. A description of the instrumentation used to measure the surface reflectance and atmosphere is presented, followed by a discussion of their placement on the site, and also their calibration. Finally, the RadCaTS ground-based results are compared to those from Aqua and Terra MODIS in 2008, and Landsat 7 ETM+ in 2009. © 2010 Copyright SPIE - The International Society for Optical Engineering.
• Czapla-Myers, J. S., Thome, K. J., & Leisso, N. P. (2010). Radiometric calibration of earth-Observing sensors using an automated test site at Railroad Valley, Nevada. Canadian Journal of Remote Sensing, 36(5), 474-487.
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  Abstract: The Remote Sensing Group (RSG) at the University of Arizona uses the reflectance-based approach to radiometrically calibrate airborne and spaceborne sensors in the solar-reflective regime. The Radiometric Calibration Test Site (RadCaTS) concept was developed in 2004 to increase the amount of ground-based data collected. RadCaTS provides a methodology to determine the surface reflectance for any arbitrary test site in the absence of ground personnel. It is founded on the reflectance-based approach and has successfully operated at Railroad Valley, Nevada, with a suite of instruments including nadir-viewing multispectral radiometers, a Cimel sun photometer, and a meteorological station. RadCaTS data are currently used by RSG to supplement those collected by on-site personnel. This work presents a description of the RadCaTS automated concept, including the process used to determine surface reflectance and top-ofatmosphere (TOA) spectral radiance. The instrumentation required to measure the surface and atmosphere is introduced, followed by discussions regarding their placement on the 1 km2 site at Railroad Valley and their calibration. Lastly, the RadCaTS results are compared with those obtained from the Landsat7 Enhanced ThematicMapper Plus (ETM+) and Terra Moderate Resolution Imaging Spectrometer (MODIS). The average percent difference in TOA spectral radiance is 4.1% between the six bands of ETM+ and RadCaTS and 3.6% between the seven land bands of Terra MODIS and RadCaTS. © 2010 CASI.
• Czapla-Myers, J. S., Czapla-Myers, J. S., Thome, K. J., Thome, K. J., Biggar, S. F., & Biggar, S. F. (2009). Calibration and characterization of a digital camera for bidirectional reflectance distribution function retrieval of vicarious calibration sites.
• Czapla-Myers, J. S., Thome, K. J., & Biggar, S. F. (2009). Calibration and characterization of a digital camera for bidirectional reflectance distribution function retrieval of vicarious calibration sites. Journal of Applied Remote Sensing, 3(1).
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  Abstract: This work describes the calibration and characterization of a commercial digital camera that is being evaluated as a potential inexpensive imaging system to measure the bidirectional reflectance factor of the test site surfaces that are used by the Remote Sensing Group for the ground-based vicarious calibration of airborne and spaceborne systems. The main advantage to using a lightweight digital camera in combination with a fisheye lens is that a test site can be simultaneously spatially and spectrally sampled with greater ease. The motivation for using an inexpensive, lightweight digital camera to measure surface bidirectional distribution factor is the ability to spatially sample many points on the ground. An additional benefit to such cameras is their ability to operate without the need for cooling, which was required on a previous camera system developed at the Remote Sensing Group. Laboratory measurements include the gain and offset, spectral responsivity, linearity, cosine response, and point spread function. The results show that the uniformity of the Nikon detector array ranges from 0.7%-1.2%. The spectral bandwidth is approximately 90 nm for the blue channel, and 110 nm for the green, and 75 nm for the red channel. Linearity measurements show that the camera responsivity is nonlinear due to the internal image-processing algorithms, and a logarithmic fitting function is suggested. Measurements of the camera response versus the angle of incidence reveal that the camera does not exhibit a cos4 falloff on detector irradiance as one would expect, which is another consequence of the internal algorithms. © 2009 Society of Photo-Optical Instrumentation Engineers.
• Czapla-Myers, J., Thome, K., Anderson, N., McCorkel, J., Leisso, N., Good, W., & Collins, S. (2009). Transmittance measurement of a heliostat facility used in the preflight radiometric calibration of Earth-observing sensors. Proceedings of SPIE - The International Society for Optical Engineering, 7452.
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  Abstract: Ball Aerospace and Technologies Corporation in Boulder, Colorado, has developed a heliostat facility that will be used to determine the preflight radiometric calibration of Earth-observing sensors that operate in the solar-reflective regime. While automatically tracking the Sun, the heliostat directs the solar beam inside a thermal vacuum chamber, where the sensor under test resides. The main advantage to using the Sun as the illumination source for preflight radiometric calibration is because it will also be the source of illumination when the sensor is in flight. This minimizes errors in the pre- and post-launch calibration due to spectral mismatches. It also allows the instrument under test to operate at irradiance values similar to those on orbit. The Remote Sensing Group at the University of Arizona measured the transmittance of the heliostat facility using three methods, the first of which is a relative measurement made using a hyperspectral portable spectroradiometer and well-calibrated reference panel. The second method is also a relative measurement, and uses a 12-channel automated solar radiometer. The final method is an absolute measurement using a hyperspectral spectroradiometer and reference panel combination, where the spectroradiometer is calibrated on site using a solar-radiation-based calibration. © 2009 SPIE.
• McCorkel, J., Thome, K., Leisso, N., Anderson, N., & Czapla-Myers, J. (2009). Radiometric characterization of hyperspectral imagers using multispectral sensors. Proceedings of SPIE - The International Society for Optical Engineering, 7452.
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  Abstract: The Remote Sensing Group (RSG) at the University of Arizona has a long history of using ground-based test sites for the calibration of airborne and satellite based sensors. Often, ground-truth measurements at these tests sites are not always successful due to weather and funding availability. Therefore, RSG has also employed automated ground instrument approaches and cross-calibration methods to verify the radiometric calibration of a sensor. The goal in the cross-calibration method is to transfer the calibration of a well-known sensor to that of a different sensor. This work studies the feasibility of determining the radiometric calibration of a hyperspectral imager using multispectral imagery. The work relies on the Moderate Resolution Imaging Spectroradiometer (MODIS) as a reference for the hyperspectral sensor Hyperion. Test sites used for comparisons are Railroad Valley in Nevada and a portion of the Libyan Desert in North Africa. Hyperion bands are compared to MODIS by band averaging Hyperion's high spectral resolution data with the relative spectral response of MODIS. The results compare cross-calibration scenarios that differ in image acquisition coincidence, test site used for the calibration, and reference sensor. Cross-calibration results are presented that show agreement between the use of coincident and non-coincident image pairs within 2% in most bands as well as similar agreement between results that employ the different MODIS sensors as a reference. © 2009 SPIE.
• Anderson, N., Thome, K., Biggar, S., & Czapla-Myers, J. S. (2008). Design and validation of a transfer radiometer. Proceedings of SPIE - The International Society for Optical Engineering, 7081.
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  Abstract: The Remote Sensing Group (RSG) at the University of Arizona Optical Sciences Center has been performing high accuracy laboratory calibration for over 20 years. An integral part of this laboratory calibration is the implementation of very accurate and repeatable transfer radiometers. This work highlights the design and characterization of one such radiometer. This particular radiometer is essentially an updated version of a previous radiometer designed and characterized by the RSG (Spyak 2000) with particular attention being paid to increased portability, ease of use and autonomous operation. This work also covers the characterization of this radiometer, including radiometric calibration, field of view, and general performance.
• Czapla-Myers, J. S., Thome, K. J., & Biggar, S. F. (2008). Design, calibration, and characterization of a field radiometer using light-emitting diodes as detectors.
• Czapla-Myers, J. S., Thome, K. J., & Biggar, S. F. (2008). Design, calibration, and characterization of a field radiometer using light-emitting diodes as detectors. Applied Optics, 47(36), 6753-6762.
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  PMID: 19104526;Abstract: The Remote Sensing Group at the University of Arizona has developed multispectral ground-viewing radiometers that use light-emitting diodes as detectors. This work describes the optical design, electrical design, and laboratory calibration of a three-channel radiometer that operates in the visible and nearinfrared region of the spectrum. The optical and electrical design of the radiometer is introduced, and then the calibration and characterization of the radiometer are described. Laboratory measurements include the spectral responsivity for each channel of the radiometer, the temperature dependence of the total responsivity for each channel, system linearity, field of view, and finally, the absolute radiometric calibration. A solar-radiation-based calibration is used to determine the absolute responsivity. © 2008 Optical Society of America.
• Czapla-Myers, J. S., Thome, K. J., Cocilovo, B. R., McCorkel, J. T., & Buchanan, J. H. (2008). Temporal, spectral, and spatial study of the automated vicarious calibration test site at Railroad Valley, Nevada. Proceedings of SPIE - The International Society for Optical Engineering, 7081.
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  Abstract: The Remote Sensing Group at the University of Arizona has developed an automated methodology and instrument suite to measure the surface reflectance of the vicarious calibration test site at Railroad Valley, Nevada. Surface reflectance is a critical variable used as one of the inputs into a radiative transfer code to predict the top-of-atmosphere radiance, and inexpensive and robust ground-viewing radiometers have been present at the site since 2004. The goal of the automated approach is to retain RSG's current 2-3% level of uncertainty while increasing the number of data sets collected throughout the year without the need for on-site personnel. A previous study was completed to determine if the number and positions of the four radiometers were adequate to spatially sample the 1-km2 large-footprint site at Railroad Valley. The preliminary study utilized one set of panchromatic data from Digital Globe's QuickBird satellite. Results from this one day showed that the positions of the four ground-viewing radiometers adequately sample the site. The work presented here expands in a spectral and temporal sense by using high-spatial-resolution data from Ikonos, QuickBird, and Landsat-7 ETM+ to determine if the locations of the ground-viewing radiometers correctly sample the site. The multispectral capability of these sensors is used to establish if there are any spectral effects, which will also help RSG to determine what spectral bands should be chosen for the new ground-viewing radiometers that are currently in development for the automated test site at Railroad Valley.
• Kuester, M. A., Czapla-Myers, J., Kaptchen, P., Good, W., Lin, T., Raymund, T. o., Biggar, S., & Thome, K. (2008). Development of a heliostat facility for solar-radiation-based calibration of earth observing sensors. Proceedings of SPIE - The International Society for Optical Engineering, 7081.
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  Abstract: A new heliostat facility at Ball Aerospace and Technologies Corporation (BATC) in Boulder, CO will allow the use of the sun as the source in the calibration of earth observing sensors. The solar spectrum is the basic energy source for such instruments; therefore it is advantageous to perform initial ground radiometric calibrations using the sun. Using this method for preflight radiometric calibration reduces uncertainties caused by the spectral mismatch between the preflight and in-flight calibration, especially in the case in which a solar diffuser is the in-flight calibration method. This method also reduces stray light concerns as the instrument diffuser is measured in situ with the same radiance level it sees on orbit. This paper presents the design of a heliostat test facility which tracks the sun and directs the solar beam into a thermal vacuum chamber, allowing the instrument under test to be kept in a safe, clean and controllable environment. Design considerations that affect the uniformity and transmission of the system are discussed. The opto-mechanical logistics of creating a heliostat that will deliver a 13-inch solar beam into a thermal vacuum chamber are also presented. This facility is currently under construction at BATC and is expected to be operational by the end of 2008.
• Thome, K. J., Czapla-Myers, J. S., & Kuester, M. A. (2008). Accuracy assessment for the radiometric calibration of Earth-observing imagers using preflight techniques relying on the sun as a source.
• Thome, K. J., Lockwood, R. B., Biggar, S. F., Anderson, N., Czapla-Myers, J., Miller, S. J., Chrien, T. G., Schiller, S. J., Silny, J. F., Glennon, M. A., & Cooley, T. W. (2008). Preflight and vicarious calibration of artemis. International Geoscience and Remote Sensing Symposium (IGARSS), 1(1), I249-I252.
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  Abstract: Pre-flight and on-orbit calibration of the spectral imagery acquired with the Advanced Responsive Tactically Effective Military Imaging Spectrometer (ARTEMIS) will make use of solar radiation-based methods. Preflight spectral calibration relies on views of a specially-coated to provide a set of known absorption features. Radiometric calibration is determined from views of a spectrally-flat panel illuminated by the sun. At-aperture radiance from the panel is determined through combined measurements by multispectral, well-calibrated transfer radiometers and a hyperspectral, field-portable spectrometer. ARTEMIS will rely on vicarious methods for the long-term evaluation of the sensor's calibration. The on-orbit radiometric calibration uses the reflectance-based method to provide at-sensor, hyperspectral radiance for the entire spectral range of ARTEMIS. Vicarious calibration of the spectral response will make use atmospheric absorption features and solar Fraunhofer lines across the solar reflective spectrum. The absolute uncertainty of the solar-based radiometric calibrations is less than 3% in spectral regions not affected by strong absorption. © 2008 IEEE.
• Thome, K., Czapla-Myers, J., Kuester, M., & Anderson, N. (2008). Accuracy assessment for the radiometric calibration of imaging sensors using preflight techniques relying on the sun as a source. Proceedings of SPIE - The International Society for Optical Engineering, 7081.
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  Abstract: The Remote Sensing Group (RSG) at the University of Arizona has performed high-accuracy radiometric calibration in the laboratory for more than 20 years in support of vicarious calibration of space-borne and airborne imaging sensors. Typical laboratory calibration relies on lamp-based sources which, while convenient to operate and control, do not simulate the solar spectrum that is the basic energy source for many of the imaging systems. Using the sun as a source for preflight radiometric calibration reduces uncertainties caused by the spectral mismatch between the preflight and inflight calibration, especially in the case in which a solar diffuser is the inflight calibration method. Difficulties in using the sun include varying atmospheric conditions, changing solar angle during the day and with season, and ensuring traceability to national standards. This paper presents several approaches using the sun as a radiometric calibration source coupled with the expected traceable accuracies for each method. The methods include direct viewing of the solar disk with the sensor of interest, illumination of the sensor's inflight solar diffuser by the sun, and illumination of an external diffuser that is imaged by the sensor. The results of the error analysis show that it is feasible to achieve preflight calibration using the sun as a source at the same level of uncertainty as those of lamp-based approaches. The error analysis is evaluated and compared to solar-radiation-based calibrations of one of RSG's laboratory-grade radiometers.
• Thome, K., Czapla-Myers, J., Leisso, N., McCorkel, J., & Buchanan, J. (2008). Intercomparison of imaging sensors using automated ground measurements. International Geoscience and Remote Sensing Symposium (IGARSS), 4(1), IV1332-IV1335.
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  Abstract: The reflectance-based method is a vicarious approach providing absolute radiometric calibration. A desire to increase the number of possible reflectance-based calibrations led the University of Arizona Remote Sensing Group (RSG) to deploy multispectral, downlooking radiometers at the RSG's Railroad Valley test site in Nevada. The radiometers are coupled with data from a sun photometer to provide the information needed for reflectance-based calibration without the need for on-site personnel. Results from these radiometers show similar uncertainties as on-site methods, and early results have led to their use with geostationary sensors, for derivation of surface bi-directional reflectance effects, and for comparisons of biases between sensors. The results show that radiometers with a single view angle are sufficient to characterize BRDF effects for Railroad Valley Playa. The results also give confidence in the automated approach as a means for cross-calibration relative to the vicarious results providing similar intercomparison results as with on-site personnel. © 2008 IEEE.
• Czapla-Myers, J. S., Thome, K. J., & Buchanan, J. H. (2007). Implication of spatial uniformity on vicarious calibration using automated test sites. Proceedings of SPIE - The International Society for Optical Engineering, 6677.
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  Abstract: A preferred method of ground-based vicarious calibration is the reflectance-based approach, which requires personnel to be present at a test site during sensor overpass. The Remote Sensing Group at the University of Arizona developed an instrumentation suite and methodology in 2004 to measure the surface and atmospheric characteristics in the absence of personnel. Field campaigns typically occur at a rate of once per month during the academic year, and increase during the summer months. The automated approach allows data to be collected during every overpass of large-footprint sensors such as Terra and Aqua MODIS, and AVHRR, which are continuously collecting data. The large-footprint-sensor site at Railroad Valley is 1 km2. In the absence of personnel, the surface bidirectional reflectance factor is measured using five nadir-viewing radiometers that are currently located at the site. Their locations are chosen based on the topography of the site in an effort to "completely" sample the 1-km2 area. This work quantifies the uncertainty in predicting the surface reflectance of the 1-km2 area based on the point measurements of the automated methodology. It also determines if the number of radiometers, and their positions, are suitable to characterize the site in a spatial sense. These uncertainties are determined through the use of portable spectroradiometers, and high-spatial-resolution QuickBird imagery.
• Czapla-Myers, J. S., Thome, K. J., & Leisso, N. P. (2007). Calibration of AVHRR sensors using the reflectance-based method. Proceedings of SPIE - The International Society for Optical Engineering, 6684.
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  Abstract: The Remote Sensing Group at the University of Arizona has been active in the vicarious calibration of numerous sensors through the use of ground-based test sites. Recent efforts have included work to develop cross-calibration information between these sensors using the results from the reflectance-based approach. The current work extends the cross-calibration to the AVHRR series of sensors, specifically NOAA-17, and NOAA-18. The results include work done based on data collected by ground-based personnel nearly coincident with the sensor overpasses. The available number of calibrations for the AVHRR series is increased through a set of ground-based radiometers that are deployed without the need for on-site personnel and have been operating for more than three years at Railroad Valley Playa. The spectral, spatial, and temporal characteristics of the 1-km2 large-footprint site at Railroad Valley are well understood. It is therefore well suited for the radiometric calibration of AVHRR, which has a nadir-viewing footprint of 1.1 × 1.1 km. The at-sensor radiance is predicted via a radiative transfer code using atmospheric data from a fully-automated solar radiometer. The results for AVHRR show that errors are currently larger for the automated data sets, but results indicate that the AVHRR sensors studied in this work are consistent with the Aqua and Terra MODIS sensors to within the uncertainties of each sensor.
• Leisso, N. P., Thome, K. J., & Czapla-Myers, J. S. (2007). Validation of the on-board radiometric calibration of the GOES I-M visible channel by reflectance-based vicarious methods. Proceedings of SPIE - The International Society for Optical Engineering, 6684.
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  Abstract: The current generation of the Geostationary Operations Environmental Satellite (GOES) platform employs a total of 5 sensors to monitor and record atmospheric conditions used in predictions of upcoming weather events. Included in this package is a 5-band imager that, from the 36,000-km geosynchronous orbit inhabited by GOES platform, enables multiple fixed full-disc surface images of the earth during the course of a 24-hour day. There is currently no on-board radiometric calibration for the visible bands of the imager and radiometric calibration relies on vicarious approaches. The Remote Sensing Group (RSG) at the University of Arizona uses a vicarious approach that relies on ground-based measurements to determine the radiometric calibration for multiple sun-synchronous and airborne visible and near-infrared sensors. The current work extends the approach to the GOES I-M series of sensor. The paper presents the methods and results of the reflectance-based method applied to the 1-km visible channel of GOES-11 using large North American high-desert test sites. Modifications to the RSG's methods to take into account the location of the test sites at large zenith angles within the full-disk GOES image. The work provides an opportunity to evaluate uncertainties of the spectral BRF of the test sites at large view angles and resulting importance to the accurate radiometric calibration of a sensor. In addition, the impact of increased path length caused by the large view angle is evaluated with an emphasis on the increased effect of the atmospheric characterization.
• Thome, K., Czapla-Myers, J., & Mccorkel, J. (2007). Retrieval of surface BRDF for reflectance-based calibration. Proceedings of SPIE - The International Society for Optical Engineering, 6677.
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  Abstract: The University of Arizona has recently deployed a set of automated, downlooking radiometers to retrieve surface reflectance of the Railroad Valley test site in Nevada. Results from these radiometers have been combined with atmospheric data from the same site to provide a reflectance-based, vicarious calibration of multiple sensors. The accuracy of the calibrations is similar to those obtained from on-site personnel. Past work has emphasized near-nadir views by the satellite sensors under study to match more closely the view geometry of the automated radiometers to minimize the effect of bi-directional effects in the surface reflectance. Extension to off-nadir views requires an accurate understanding of the surface BRDF. Surface bi-directional reflectance effects have always played a key role in the accuracy of the vicarious calibration of imaging sensors. Such effects are especially important for the large, off-nadir views of sensors such as AVHRR and MODIS. The current work presents a method for retrieving the BRDF using the nadir-viewing data from the automated radiometers throughout the day. The concept of reciprocity is used to derive the reflectance as a function of view angle based on the measurements as a function of solar zenith angle. Comparisons of the results from this approach are compared to MODIS-derived BRDF data as well as ground-based measurements.
• D'Amico, J., Thome, K., & Czapla-Myers, J. (2006). Validation of large-footprint, reflectance-based calibration using coincident MODIS and ASTER data. Proceedings of SPIE - The International Society for Optical Engineering, 6296.
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  Abstract: The Remote Sensing Group at the University of Arizona has been using reflectance-based vicarious calibration of earth-observing satellites since the 1980s. Among the sensors characterized by the group are the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and the MODerate Resolution Imaging Spectroradiometer (MODIS) that are both on NASA's Terra platform. The spatial resolution of MODIS requires that the group use a large-sized site such as Railroad Valley Playa, Nevada as a test site. In addition, the large footprint size of MODIS forced a modification to the ground-sampling scheme for the surface reflectance retrieval. This work examines the impact of the new sampling scheme through coincident ASTER and MODIS imagery making use of the higher resolution spatial resolution of ASTER. ASTER and MODIS imagery were obtained for dates on which both sensors imaged the Railroad Valley test site and ground-based data were collected at the site. The results of the comparison between the sensors shows differences in the radiometric calibration that exceed the accuracy requirements of the sensors, but that the sampling strategy for large-footprint sensors produces reflectance-based results at the same 3% level of accuracy as that for small-footprint sensors.
• Czapla-Myers, J., Thome, K., & Biggar, S. (2005). Unmanned vicarious calibration for large-footprint sensors. Proceedings of SPIE - The International Society for Optical Engineering, 5882, 1-10.
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  Abstract: The Remote Sensing Group (RSG) at the University of Arizona is currently developing inexpensive, unmanned radiometers based on light-emitting diodes (LEDs). This work describes these radiometers, which are now used as part of the extensive vicarious calibration research that has been conducted since the mid-1980s and presently includes such sensors as MODIS, ASTER, AVHRR, Landsat-7 ETM+, Ikonos, and Quickbird. RSG performs a typical vicarious calibration with on-site personnel measuring atmospheric and surface conditions at a test site during actual sensor overpass. A radiative-transfer code is used to calculate a top-of-atmosphere radiance, which is then compared to that reported by the sensor under test. Data collection can be limited by poor weather conditions, and in addition, it is generally difficult to collect data during every sensor overpass due to the large travel distances to the test sites. The LED radiometers are being developed as a solution to the temporal sampling limitations seen in the past. They are used in a nadir-viewing configuration to measure the surface reflectance in three spectral bands, while the atmospheric conditions are measured using a Cimel sun photometer. The data from these two instruments are used to produce a top-of-atmosphere radiance during overpass when no personnel are present. Results of laboratory calibration measurements of the radiometers are described, and include the spectral responsivity, temperature dependence of the spectral responsivity, and calibration coefficient. Finally, the top-of-atmosphere radiances produced by the unmanned vicarious instrumentation are compared to those reported by Aqua MODIS for three days in March 2005.
• Myers, J. S., & Hildum, E. (2004). NASA UAV sensor development: Works in progress. Collection of Technical Papers - AIAA 3rd "Unmanned-Unlimited" Technical Conference, Workshop, and Exhibit, 1, 328-334.
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  Abstract: A new modular remote sensing system is being built for service on UAVs, with the intent to conduct demonstration missions for Earth science research. The basic design parameters and system specifications will be discussed, especially as they pertain to the unique requirements of the high altitude UAV operating environment. System configurations for oceanographic, atmospheric, and land-processes research will be described, as well as some of the unique technical features of the overall system. Copyright © 2004 by the American Institute of Aeronautics and Astronautics, Inc.
• Thome, K., Czapla-Myers, J., & Biggar, S. (2004). Ground-monitor radiometer system for vicarious calibration. Proceedings of SPIE - The International Society for Optical Engineering, 5546, 223-232.
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  Abstract: The Remote Sensing Group at the University of Arizona has been active in the vicarious calibration of numerous sensors through the use of ground-based test sites. Application of these approaches has been limited in the past by the fact that ground-based personnel must be present at the time of the sensor overpass. This work presents the design and implementation of a set of ground-based, ground-viewing radiometers that are deployed without the need for on-site personnel. The radiometers are based on LED detectors allowing them to be robust and inexpensive and combining the results of these measurements with known calibration of the sensors and a suitable surface BRDF model, allows the surface spectral reflectance of the test site to be determined for the sensor overpass. The at-sensor radiance can be predicted via a radiative transfer code using atmospheric data from a fully-automated solar radiometer. Early results from this approach are presented for the Landsat ETM+ and Terra and Aqua MODIS sensors. These results show that errors are currently larger for this method than those with ground-based personnel, but the increased number of calibration opportunities should improve the overall understanding of the sensor calibration.
• Thome, K., Czapla-Myers, J., & Biggar, S. (2003). Vicarious calibration of Aqua and Terra MODIS. Proceedings of SPIE - The International Society for Optical Engineering, 5151, 395-405.
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  Abstract: The Moderate Resolution Imaging Spectroradiometer (MODIS) is onboard both the Terra and Aqua platforms. An important aspect of the use of MODIS, and other Earth Science Enterprise sensors, has been the characterization and calibration of the sensors and validation of their data products. The Remote Sensing Group at the University of Arizona has been active in this area through the use of ground-based test sites. This paper presents the results from the reflectance-base approach using the Railroad Valley Playa test site in Nevada for both Aqua and Terra MODIS. The key to the approach is the measurement of surface reflectance over a 1-km 2 area of the playa and results from this method shows agreement with both MODIS sensors to better than 5%. Early results indicate that while the two sensors both agree with the ground-based measurements to within the uncertainties of the reflectance-based approach, there were significant differences between the Aqua and Terra MODIS for data prior to September 2002. Recent results indicate that this bias, if any, is now within the uncertainties of the reflectance-based method of calibration.
• Czapla-Myers, J. S., Thome, K. J., & Biggar, S. F. (2002). Optical sensor package for multiangle measurements of surface reflectance. Proceedings of SPIE - The International Society for Optical Engineering, 4480, 326-333.
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  Abstract: The Remote Sensing Group of the Optical Sciences Center at the University of Arizona has performed the vicarious calibration of satellite sensors since the 1980s. Ground-based measurements of atmospheric and surface properties, including the surface bidirectional reflectance distribution function (BRDF), are conducted during a satellite or airborne sensor overpass and the at-sensor radiance is calculated using these properties as input to a radiative transfer code. Recently, the Remote Sensing Group has investigated an imaging radiometer based on an astronomical-grade 1024 × 1024-pixel silicon CCD array that was developed and calibrated for ground-based measurements of BRDF. The results of that study have been used to examine the feasibility of a lightweight instrument package for measurements of surface BRDF based on a combination of nonimaging radiometers and inexpensive digital cameras. The current work presents a preliminary design of such a system including specifications for ground-based operations of the system to characterize the BRDF of test sites used by the Remote Sensing Group. Also included is a preliminary evaluation of a Nikon 990 digital camera coupled with a 1.7-mm focal length fisheye lens to determine the level of accuracy that can be obtained in surface BRDF.
• Hook, S. J., Myers, J. J., Thome, K. J., Fitzgerald, M., & Kahle, A. B. (2001). The MODIS/ASTER airborne simulator (MASTER) - A new instrument for earth science studies. Remote Sensing of Environment, 76(1), 93-102.
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  Abstract: The MODIS/ASTER Airborne Simulator was developed for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Moderate Resolution Imaging Spectroradiometer (MODIS) projects. ASTER and MODIS are both spaceborne imaging instruments on the Terra platform launched in the fall of 1999. Currently MASTER is flown on the Department of Energy (DOE) King Air Beachcraft B200 aircraft and the NASA DC-8. In order to validate the in-flight performance of the instrument, the Jet Propulsion Laboratory and the University of Arizona conducted a joint experiment in December 1998. The experiment involved overflights of the MASTER instrument at two sites at three elevations (2000, 4000, and 6000 m). The two sites: Ivanpah Playa, California, and Lake Mead, Nevada, were selected to validate the visible - shortwave infrared and thermal infrared (TIR) channels, respectively. At Ivanpah Playa, a spectrometer was used to determine the surface reflectance and a sun photometer used to obtain the optical depth. At Lake Mead contact and radiometric surface lake temperatures were measured by buoy-mounted thermistors and self-calibrating radiometers, respectively. Atmospheric profiles of temperature, pressure, and relative humidity were obtained by launching an atmospheric sounding balloon. The measured surface radiances were then propagated to the at-sensor radiance using radiative transfer models driven by the local atmospheric data. There was excellent agreement between the predicted radiance at sensor and the measured radiance at sensor at all three altitudes. The percent difference between the channels not strongly affected by the atmosphere in the visible - shortwave infrared was typically 1-5% and the percent difference between the TIR channels not strongly affected by the atmosphere was typically less than 0.5%. These results indicate the MASTER instrument should provide a well-calibrated instrument for Earth Science Studies. It should prove particularly valuable for those studies that leverage information across the electromagnetic spectrum from the visible to the TIR. © 2001 Elsevier Science Inc.
• Czapla-Myers, J., Gray, L. H., Hollinger, A., Miller, J. R., & Duggan, P. (1999). Spectral bandwidth characterization methodology for imaging spectrometers: application to casi. Proceedings of SPIE - The International Society for Optical Engineering, 3717, 177-184.
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  Abstract: In 1993 and 1996, laboratory measurements were conducted at the Instrument Services Laboratory (ISL) at the Center for Research in Earth and Space Technology (CRESTech) in order to characterize the spectral bandwidth. Results demonstrate that the spectral bandwidth of the casi decreased due to improvements made by the manufacturer, ITRES. The shape of the bandpass curve as a function of wavelength also changed significantly. In 1993, it was very wavelength dependent with a parabolic shape, while in 1996 it was less wavelength dependent. Spectral bandwidth departures from nominal values across the sensor's field of view, spectral range and operating f/# were documented.
• Myers, J. (1999). MODIS and ASTER airborne simulators. Proceedings of SPIE - The International Society for Optical Engineering, 3750, 269-273.
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  Abstract: The NASA has built two airborne sensors to simulate space-borne instruments to be flown on the EOS (Earth Observing System) AM-1 Terra satellite, scheduled for launch in 1999. The intent of these airborne systems is to provide initial, or 'precursor' data sets to EOS investigators for algorithm development, as well as to conduct calibration and validation under-flights after the AM-1 platform has been launched. The MODIS Airborne Simulator (MAS,) and the MODIS/ASTER Simulator (MASTER,) were designed to support investigations by the Moderate Resolution Imaging Spectro-radiometer, and the Advanced Spaceborne Thermal Emission and Reflection Radiometer science teams, respectively.
• Wan, Z., Zhang, Y., Xialin, M. a., King, M. D., Myers, J. S., & Xiaowen, L. i. (1999). Vicarious calibration of the moderate-resolution imaging spectroradiometer airborne simulator thermal-infrared channels. Applied Optics, 38(30), 6294-6306.
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  PMID: 18324156;Abstract: We made an experimental vicarious calibration of the Moderate Resolution Imaging Spectroradiometer (MODIS) Airborne Simulator (MAS) thermal infrared (TIR) channel data acquired in the field campaign near Mono Lake, Calif, on 10 March 1998 to demonstrate the advantage of using high-elevation sites in dry atmospheric conditions for vicarious calibration. With three lake-surface sites and one snow-field site, we estimated the MAS noise-equivalent temperature difference as 0.7-1.0 °C for bands 30-32 in the 3.68-4.13-μm region and 0.1-0.5 °C for bands 42, 45,46, and 48 in the 8-13.5-μm region. This study shows that the MAS calibration error is within ±0.4 °C in the split-window channels (at 11 and 12 μm) and larger in other TIR channels based on the MAS data over Mono Lake and in situ measurement data over the snow-field site. © 1999 Optical Society of America.
• King, M. D., Menzel, W. P., Grant, P. S., Myers, J. S., Arnold, G. T., Platnick, S. E., Gumley, L. E., Tsay, S., Moeller, C. C., Fitzgerald, M., Brown, K. S., & Osterwisch, F. G. (1996). Airborne scanning spectrometer for remote sensing of cloud, aerosol, water vapor, and surface properties. Journal of Atmospheric and Oceanic Technology, 13(4), 777-794.
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  Abstract: An airborne scanning spectrometer was developed for measuring reflected solar and emitted thermal radiation in 50 narrowband channels between 0.55 and 14.2 μm. The instrument provides multispectral images of outgoing radiation for purposes of developing and validating algorithms for the remote sensing of cloud, aerosol, water vapor, and surface properties from space. The spectrometer scans a swath width of 37 km, perpendicular to the aircraft flight track, with a 2.5-mrad instantaneous field of view. Images are thereby produced with a spatial resolution of 50 m at nadir from a nominal aircraft altitude of 20 km. Nineteen of the spectral bands correspond closely to comparable bands on the Moderate Resolution Imaging Spectroradiometer (MODIS), a facility instrument being developed for the Earth Observing System to be launched in the late 1990s. This paper describes the optical, mechanical, electrical, and data acquisition system design of the MODIS Airborne Simulator and presents some early results obtained from measurements acquired aboard the National Aeronautics and Space Administration ER-2 aircraft that illustrate the performance and quality of the data produced by this instrument.
• Ambrosia, V. G., Myers, J. S., Ekstrand, R. E., & Fitzgerald, M. T. (1991). Integration of airborne Thematic Mapper Simulator (TMS) data and digitized aerial photography via an ISH transformation. Geocarto International, 6(2), 45-48.
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  Abstract: The authors have shown a simple method for enhancing the spatial and spectral resolution of disparate data sets. The two data sets, once co-registered, were then subjected to ISH transformations in order to "blend' the high spatial resolution (3.7 m), digitized RC-10 photography with the high spectral (12-bands), lower spatial (24.6 m) resolution TMS digital data. The resultant merged products allow large-scale mapping, eases photo-interpretation, and can be derived for any of the 12 available TMS spectral bands. -from Authors

Proceedings Publications

• Anderson, N. J., & Czapla-Myers, J. S. (2022).

  The University of Arizona's radiometric calibration test site (RadCaTS): lessons learned after 10 years in operation at Railroad Valley, Nevada

  . In Earth Observing Systems XXVII, 12232.
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  The Radiometric Calibration Test Site (RadCaTS) was developed by the Remote Sensing Group of the Wyant College of Optical Sciences at the University of Arizona in the early 2000s. During the prototyping phase, RadCaTS was used to supplement the in situ data that were routinely collected by on-site personnel using the traditional reflectance-based approach. A data processing methodology was developed, tested, and compared to the reflectance-based results during this stage. The experience gained in this process resulted in the development of radiometrically-stable, all-weather, groundviewing radiometers (GVRs), the first of which were deployed in 2012. Additional upgrades over the past ten years have included a satellite uplink station, upgraded Cimel CE-318T solar-lunar photometer, and a GVR with linear motion. This work provides an overview of RadCaTS, describes the lessons learned during the past ten years of operation, and also a summary of the radiometric calibration and validation results for such sensors as Landsat 7 ETM+, Landsat 8 and 9 OLI, Terra and Aqua MODIS, SNPP and NOAA-20 VIIRS, Sentinel-2A and -2B MSI, and GOES-16 and -17 ABI.
• Anderson, N., Czapla-myers, J. S., Salehi, F., Thome, K. J., & Wenny, B. N. (2021).

  Solar radiation based calibration results from an ultra-portable field transfer radiometer used in vicarious calibrations

  . In Earth Observing Systems XXVI, 11829.
• Anderson, N., Czapla-myers, J. S., Thome, K., & Wenny, B. N. (2020).

  Railroad Valley Radiometric Calibration Test Site (RadCaTS) as Part of a Global Radiometric Calibration Network (RadCalNet)

  . In IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 6413-6416.
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  The Radiometric Calibration Network (RadCalNet) is a coordinated multinational effort to provide in situ data that are suitable for the radiometric calibration and validation of Earth observation sensors that operate in the visible to shortwave infrared solar reflective spectral region (400 nm to 1000 nm). The main goals of RadCalNet are to provide top-of-atmosphere reflectance data to the scientific community, standardize data collection protocols for automated test sites, and to document the SI-traceable uncertainty budgets for each automated test site, of which there are currently four. The data available from RadCalNet are suitable for the calibration and validation of spaceborne imaging spectrometers. The work presented here provides a description of RadCalNet as well as a sample of the current results from the Radiometric Calibration Test Site (RadCaTS), which is located at Railroad Valley, Nevada, USA. Selected sensors for comparison include Terra and Aqua MODIS, SNPP and NOAA-20 VIIRS, and Sentinel-3A and −3B OLCI.
• Czapla-Myers, J. S., & Anderson, N. J. (2019, 2019). Intercomparison of the GOES-16 and -17 Advanced Baseline Imager with low-Earth orbit sensors. In Intercomparison of the GOES-16 and -17 Advanced Baseline Imager with low-Earth orbit sensors, 11127.
• Abdelatif, A., Anderson, N., Hernandez, O., & Czapla-Myers, J. (2018, 2018). Prism spectrometer analysis for field use. In Prism spectrometer analysis for field use, 10764, 10.
• Czapla-Myers, J. S., & Anderson, N. J. (2018, 2018). Intercomparison of Earth-Observing Sensors Using the Radiometric Calibration Test Site (RadCaTS). In Intercomparison of Earth-Observing Sensors Using the Radiometric Calibration Test Site (RadCaTS), 4336-4338.
• Czapla-Myers, J. S., & Anderson, N. J. (2018, 2018). Post-launch radiometric validation of the GOES-16 Advanced Baseline Imager (ABI). In Post-launch radiometric validation of the GOES-16 Advanced Baseline Imager (ABI), 10785, 6.
• Czapla-Myers, J. S., Coburn, C. A., Thome, K. J., Wenny, B. N., & Anderson, N. J. (2018, 2018). Directional reflectance studies in support of the Radiometric Calibration Test Site (RadCaTS) at Railroad Valley. In Directional reflectance studies in support of the Radiometric Calibration Test Site (RadCaTS) at Railroad Valley, 10764, 9.
• Lau, I. C., Ong, C., Thome, K. J., Wenny, B., Mueller, A., Heiden, U., Czapla-Myers, J. .., Biggar, S., Anderson, N., McGonigle, L., Thomas, W., Barrientos, C., & Itoh, Y. (2018, 2018). Intercomparison of Field Methods for Acquiring Ground Reflectance at Railroad Valley Playa for Spectral Calibration of Satellite Data. In Intercomparison of Field Methods for Acquiring Ground Reflectance at Railroad Valley Playa for Spectral Calibration of Satellite Data, 186-188.
• Czapla-Myers, J. S., & Anderson, N. J. (2017, 2017). Analysis of a commercial small unmanned airborne system (sUAS) in support of the Radiometric Calibration Test Site (RadCaTS) at Railroad Valley. In Analysis of a commercial small unmanned airborne system (sUAS) in support of the Radiometric Calibration Test Site (RadCaTS) at Railroad Valley, 10402, 10.
• Czapla-Myers, J., McCorkel, J., Anderson, N., & Biggar, S. (2017, 2017). Earth-observing satellite intercomparison using the Radiometric Calibration Test Site at Railroad Valley. In Earth-observing satellite intercomparison using the Radiometric Calibration Test Site at Railroad Valley, 12, 9.
• Scanlon, T., Greenwell, C., Czapla-Myers, J., Anderson, N., Goodman, T., Thome, K., Wolliams, E., Porrovecchio, G., LinduÅ¡ka, P., Å míd, M., & Fox, N. P. (2017, 2017). Ground comparisons at RadCalNet sites to determine the equivalence of sites within the network. In Ground comparisons at RadCalNet sites to determine the equivalence of sites within the network, 10423, 13.
• Thome, K., Czapla-Myers, J., Wenny, B., & Anderson, N. (2017, 2017). Calibration and use of an ultra-portable field transfer radiometer for automated vicarious calibration. In Calibration and use of an ultra-portable field transfer radiometer for automated vicarious calibration, 10402, 11.
• Barsi, J. A., Markham, B. L., Czapla-Myers, J. S., Helder, D. L., Hook, S. J., Schott, J. R., & Haque, M. O. (2016, 2016). Landsat-7 ETM+ radiometric calibration status. In Landsat-7 ETM+ radiometric calibration status, 9972, 99720C-99720C-12.
• Czapla-Myers, J., Bouvet, M., & Wenny, B. N. (2016, 2016). The Radiometric Calibration Network (RadCalNet): a Global Calibration and Validation Test Site Network. In The Radiometric Calibration Network (RadCalNet): a Global Calibration and Validation Test Site Network.
• Ong, C., Mueller, A., Thome, K., Bachmann, M., Czapla-Myers, J. .., Holzwarth, S., Khalsa, S. J., MacLellan, C., Malthus, T., Nightingale, J., Pierce, L., & Yamamoto, H. (2016, 2016). Report on International Spaceborne Imaging Spectroscopy Technical Committee calibration and validation workshop, national environment research council field spectroscopy facility, University of Edinburgh. In Report on International Spaceborne Imaging Spectroscopy Technical Committee calibration and validation workshop, national environment research council field spectroscopy facility, University of Edinburgh, 1909-1911.
• Anderson, N., Thome, K., Czapla-Myers, J., & Biggar, S. (2015, 2015). Design of an ultra-portable field transfer radiometer supporting automated vicarious calibration. In Design of an ultra-portable field transfer radiometer supporting automated vicarious calibration, 9607, 960709-960709-9.
• Czapla-Myers, J. (2015, 2015). Atmospheric measurement analysis for the Radiometric Calibration Test Site (RadCaTS). In Atmospheric measurement analysis for the Radiometric Calibration Test Site (RadCaTS), 9607, 96070A-96070A-8.
• McCorkel, J., Czapla-Myers, J. .., Thome, K., & Wenny, B. (2015, 2015). Online resource for Earth-observing satellite sensor calibration. In Online resource for Earth-observing satellite sensor calibration, 9607, 96070B-96070B-8.
• Czapla-Myers, J. S., Thome, K., Biggar, S., Anderson, N. J., & SPIE, . (2014, 2014). The absolute radiometric calibration of Terra imaging sensors: MODIS, MISR, and ASTER. In The absolute radiometric calibration of Terra imaging sensors: MODIS, MISR, and ASTER, 9218.
• Czapla-Myers, J., Anderson, N., Thome, K., & Biggar, S. (2014, 2014). The absolute radiometric calibration of the Landsat 8 Operational Land Imager using the reflectance-based approach and the Radiometric Calibration Test Site (RadCaTS). In The absolute radiometric calibration of the Landsat 8 Operational Land Imager using the reflectance-based approach and the Radiometric Calibration Test Site (RadCaTS), 9218, 921819.
• Anderson, N. J., & Czapla-Myers, J. S. (2013, 2013). Ground viewing radiometer characterization, implementation and calibration applications: a summary after two years of field deployment. In Ground viewing radiometer characterization, implementation and calibration applications: a summary after two years of field deployment, 8866, 88660N-88660N-10.
• Czapla-Myers, J. S., Anderson, N. J., & Biggar, S. F. (2013, 2013). Early ground-based vicarious calibration results for Landsat 8 OLI. In Early ground-based vicarious calibration results for Landsat 8 OLI, 8866, 88660S-88660S-10.
• Czapla-Myers, J. S., Leisso, N. P., Anderson, N. J., Biggar, S. F., Shen, S. S., & Lewis, P. E. (2012, 2012). On-orbit radiometric calibration of Earth-observing sensors using the Radiometric Calibration Test Site (RadCaTS). In On-orbit radiometric calibration of Earth-observing sensors using the Radiometric Calibration Test Site (RadCaTS), 8390, 83902B-9.
• Czapla-Myers, J., & Leisso, N. (2011).

  Comparison of diffuse sky irradiance calculation methods and effect on surface reflectance retrieval from an automated radiometric calibration test site

  . In Earth Observing Systems XVI, 8153.
• Leisso, N., Czapla-Myers, J., Butler, J. J., Xiong, X., & Gu, X. (2011, 2011). Comparison of diffuse sky irradiance calculation methods and effect on surface reflectance retrieval from an automated radiometric calibration test site. In Comparison of diffuse sky irradiance calculation methods and effect on surface reflectance retrieval from an automated radiometric calibration test site, 8153, 815310-11.
• Czapla-Myers, J. S., & Leisso, N. P. (2010, 2010). Recent results from the Radiometric Calibration Test Site (RadCaTS) at Railroad Valley, Nevada. In Recent results from the Radiometric Calibration Test Site (RadCaTS) at Railroad Valley, Nevada, 7807, 78070R-9.
• Czapla-Myers, J. .., Thome, K., Anderson, N., McCorkel, J., Leisso, N., Good, W., & Collins, S. (2009, 2009). Transmittance measurement of a heliostat facility used in the preflight radiometric calibration of Earth-observing sensors. In Transmittance measurement of a heliostat facility used in the preflight radiometric calibration of Earth-observing sensors, 7452, 74520P-8.
• McCorkel, J., Thome, K., Leisso, N., Anderson, N., & Czapla-Myers, J. (2009, 2009). Radiometric characterization of hyperspectral imagers using multispectral sensors. In Radiometric characterization of hyperspectral imagers using multispectral sensors, 7452, 745210-11.
• Anderson, N., Thome, K., Biggar, S., & Czapla-Myers, J. S. (2008, 2008). Design and validation of a transfer radiometer. In Design and validation of a transfer radiometer, 7081, 708104-8.
• Czapla-Myers, J. S., Thome, K. J., Cocilovo, B. R., McCorkel, J. T., & Buchanan, J. H. (2008, 2008). Temporal, spectral, and spatial study of the automated vicarious calibration test site at Railroad Valley, Nevada. In Temporal, spectral, and spatial study of the automated vicarious calibration test site at Railroad Valley, Nevada, 7081, 70810I-9.
• Kuester, M. A., Czapla-Myers, J., Kaptchen, P., Good, W., Lin, T., To, R., Biggar, S., & Thome, K. (2008, 2008). Development of a heliostat facility for solar-radiation-based calibration of earth observing sensors. In Development of a heliostat facility for solar-radiation-based calibration of earth observing sensors, 7081, 708119-1 - 708119-8.
• Thome, K. J., Biggar, S. F., Anderson, N., Czapla-Myers, J. .., Lockwood, R. B., Miller, S. J., Cooley, T. W., Chrien, T. G., Schiller, S. J., Silny, J. F., & Glennon, M. A. (2008, 2008). Preflight and Vicarious Calibration of ARTEMIS. In Preflight and Vicarious Calibration of ARTEMIS, 1, I-249 - I-252.
• Thome, K., Czapla-Myers, J. .., Leisso, N., McCorkel, J., & Buchanan, J. (2008, 2008). Intercomparison of Imaging Sensors using Automated Ground Measurements. In Intercomparison of Imaging Sensors using Automated Ground Measurements, 4, IV - 1332-IV - 1335.
• Thome, K., McCorkel, J., & Czapla-Myers, J. .. (2008, 2008). Inflight Intersensor Radiometric Calibration using the Reflectance-Based Method for Landsat-Type Sensors. In Inflight Intersensor Radiometric Calibration using the Reflectance-Based Method for Landsat-Type Sensors.
• Czapla-Myers, J. S., Thome, K. J., & Buchanan, J. H. (2007, 2007). Implication of spatial uniformity on vicarious calibration using automated test sites. In Implication of spatial uniformity on vicarious calibration using automated test sites, 6677, 66770U-10.
• Czapla-Myers, J. S., Thome, K. J., & Leisso, N. P. (2007, 2007). Calibration of AVHRR sensors using the reflectance-based method. In Calibration of AVHRR sensors using the reflectance-based method, 6684, 668407-10.
• Leisso, N. P., Thome, K. J., & Czapla-Myers, J. S. (2007, 2007). Validation of the onboard radiometric calibration of the GOES I-M visible channel by reflectance-based vicarious methods. In Validation of the onboard radiometric calibration of the GOES I-M visible channel by reflectance-based vicarious methods, 6684, 668404-10.
• Thome, K., Thome, K., Czapla-Myers, J. .., Czapla-Myers, J. .., McCorkel, J., McCorkel, J., Butler, J. J., Butler, J. J., Xiong, J., & Xiong, J. (2007, 2007). Retrieval of surface BRDF for reflectance-based calibration. In Retrieval of surface BRDF for reflectance-based calibration, 6677, 66770T1-66770T11.
• D'Amico, J., Thome, K., Czapla-Myers, J. .., Butler, J. J., & Xiong, J. (2006, 2006). Validation of large-footprint reflectance-based calibration using coincident MODIS and ASTER data. In Validation of large-footprint reflectance-based calibration using coincident MODIS and ASTER data, 6296, 629612-8.
• Czapla-Myers, J., Thome, K., & Biggar, S. (2005, 2005). Unmanned vicarious calibration for large-footprint sensors. In Unmanned vicarious calibration for large-footprint sensors, 5882, 588218-10.
• Thome, K. J., Czapla-Myers, J. S., & Scott, K. (2005, 2005). Automated ground system for reflectance-based calibration. In Automated ground system for reflectance-based calibration, 1-13.
• Thome, K. J., Czapla-Myers, J. S., Biggar, S. F., Shen, S. S., & Lewis, P. E. (2004, 2004). Ground-monitor radiometer system for vicarious calibration. In Ground-monitor radiometer system for vicarious calibration, 5546, 223-232.
• Thome, K. J., Czapla-Myers, J. S., Biggar, S. F., & Barnes, W. (2003, 2003). Vicarious calibration of Aqua and Terra MODIS. In Vicarious calibration of Aqua and Terra MODIS, 5151, 395-405.
• Czapla-Myers, J. S., Thome, K. J., & Biggar, S. F. (2002, 2002). Optical sensor package for multiangle measurements of surface reflectance. In Optical sensor package for multiangle measurements of surface reflectance, 4480, 326-333.
• Czapla-Myers, J. S., Gray, L. H., Hollinger, A. B., Miller, J. R., Duggan, P., Shen, S. S., & Descour, M. R. (1999, 1999). Spectral bandwidth characterization methodology for imaging spectrometers: application to CASI. In Spectral bandwidth characterization methodology for imaging spectrometers: application to CASI, 3717, 177-184.

Others

• Czapla-Myers, J., & Woolliams, E. (2018, 2018). Uncertainty Analysis Statement – RVUS. www.radcalnet.org/#!/sites/RVUS
• Hankerson, J. (2018, 2019-01-08t01:52:18z). Automated Motion Control of a Ground-Viewing Radiometer System. http://hdl.handle.net/10150/631328
• Meyers, D., Maiersperger, T., Jenkerson, C., Czapla-Myers, J. S., Van Leeuwen, W. J., Grey, J., Friedl, M., Zhang, X., Tsend-Ayush, J., Miura, T., Barreto Munoz, A., & Didan, K. (2017, 06). Multi-Sensor Vegetation Index and Phenology Earth Science Data Records Algorithm Theoretical Basis Document and User Guide. NASA/LP-DAAC,. https://lpdaac.usgs.gov/sites/default/files/public/measures/docs/VIP_ESDRs_ATBD_And_UsersGuide.pdf. https://lpdaac.usgs.gov/sites/default/files/public/measures/docs/VIP_ESDRs_ATBD_And_UsersGuide.pdf
• Czapla-Myers, J. S. (2006, 2006). Automated Ground-Based Methodology in Support of Vicarious Calibration.