On-orbit performance of MODIS solar diffuser stability monitor

摘要: Raytheon Space and Airborne Systems, El Segundo, California 90245, United StatesAbstract. Moderate Resolution Imaging Spectroradiometer (MODIS) is currently operated onboth the Terra Aqua spacecraft. It collects data in 20 reflective solar bands (RSB) 16thermal emissive bands. MODIS RSB calibration reflectance based via an on-board dif-fuser (SD). On-orbit changes SD bidirectional factor are tracked by diffuser stability monitor (SDSM). The SDSM functions as independent ratioingradiometer with nine filtered detectors, covering wavelengths thevisible (VIS) andnear-infra-red(NIR)spectral regions.Abrief overviewofSDSMdesignfunctions, on-orbitoperations,andperformance for both provided. In addition to on-orbit deg-radation at different wavelengths, detector responses their potentialimpact on tracking degradation examined. After more than 12 years of on-orbitoperation, has shown varying from 0.6% 0.94 μm 19.0% at0.41 μm. Due frequent exposure longer operation time, SDhas experienced a much larger degradation, 2.3% 48.0% 0.41 μm.For MODIS, shorter wave-lengths.Meanwhile,theSDSM responseshavealso experiencedwavelength-dependentdegradation. largest change responses, however, occurred longerNIR wavelengths. Since launch, systems have con-tinued nominal operations, enabling critical parameters be derivedin support RSBon-orbit calibration. strategies developed lessons learned MODISSDSMoperations,andapreliminary performancecomparisonwiththeS-NPPVIIRSSDSMarediscussed.