On-Orbit Noise Characterization for MODIS Reflective Solar Bands

MODIS collects data in 36 spectral bands, with wavelengths from 0.41 to 14.4 mum, and at three nadir spatial resolutions: 0.25 km, 0.5 km, and 1 km. MODIS reflective solar bands (RSB) on-orbit calibration is performed using an on-board solar diffuser (SD) and a solar diffuser stability monitor (SDSM). In addition to calibration coefficients, the SD observations are used to characterize detector signal-to-noise ratios (SNR). Due to spacecraft movement, the SD panel solar illumination angles change continually. Consequently, each detector's response to the SD varies continuously with the solar illumination onto the SD, enabling its SNR to be determined at different responses or signal levels. On-orbit results show that both Terra and Aqua MODIS RSB detectors have performed well since launch. Except for a few noisy and inoperable detectors identified pre-launch, most RSB detectors continue to meet the SNR requirements.