Angal_etal2009 Proceedings Bellingham, Wash. Society of Photo-Optical Instrumentation Engineers (SPIE) 5 August 2009 2009 Atmospheric and Environmental Remote Sensing Data Processing and Utilization V-Readiness for GEOSS III Proceedings of SPIE Vol. 7456 AngalA. XiongX. ChoiT.J. ChanderGyanesh WuA. San Diego, Calif. GoldbergM.D. BloomH.J. in Using the Sonoran Desert test site to monitor the long-term radiometric stability of the Landsat TM/ETM+ and Terra MODIS sensors article number 745601 Pseudo-invariant ground targets have been extensively used to monitor the long-term radiometric calibration stability of remote sensing instruments. The NASA MODIS Characterization Support Team (MCST), in collaboration with members from the U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center, has previously demonstrated the use of pseudo-invariant ground sites for the long-term stability monitoring of Terra MODIS and Landsat 7 ETM+ sensors. This paper focuses on the results derived from observations made over the Sonoran Desert. Additionally, Landsat 5 TM data over the Sonoran Desert site were used to evaluate the temporal stability of this site. Top-ofatmosphere (TOA) reflectances were computed for the closely matched TM, ETM+, and MODIS spectral bands over selected regions of interest. The impacts due to different viewing geometries, or the effect of test site Bi-directional Reflectance Distribution Function (BRDF), are also presented.