Assessments of MODIS On-orbit Spatial and Spectral Characterization

MODIS collects data in 36 spectral bands covering wavelengths from 0.41 to 14.4 micron and at 250 m (bands 1-2), 500 m (bands 3-7), and 1 km (bands 8-36) nadir spatial resolutions. MODIS spectral bands are located according to their wavelengths on four focal plane assemblies (FPAs): VIS, NIR, S/MWIR, and LWIR. In addition to on-board solar diffuser (SD) and blackbody (BB) designed for sensor radiometric calibration, MODIS was built with a unique device, the spectro-radiometric calibration assembly (SRCA) that can be operated in different configurations to characterize sensor spatial and spectral performance. This paper briefly describes MODIS SRCA design, configurations, and functions. It provides an overview of SRCA calibration activities and operational strategies implemented for both Terra and Aqua MODIS and illustrates their on-orbit spatial and spectral performance. Results presented and discussed in this analysis include on-orbit changes in sensor key spatial and spectral performance parameters, such as band-to-band registration (BBR), FPA-to-FPA registration (FFR), modulation transfer function (MTF), center wavelengths (CW), and bandwidths (BW). Also discussed are the use of information derived from MODIS SRCA, lessons learned from its on-orbit operation, and plans for future improvements.