Subsample difference correction for Terra MODIS SWIR bands 5-7 using lunar observations

摘要

The Moderate Resolution Imaging Spectroradiometer (MODIS) is one of the key instruments on board the Terra (EOS AM-1) spacecraft. MODIS has 36 spectral bands ranging in wavelength between 0.4 and 14.2 μm. at three spatial resolutions of 250 m (bands 1-2), 500 m (bands 3-7), and 1 km (bands 8-36). For eaeh 1-km sample, the 250-m and 500-m bands use 4 and 2 detectors with each acquiring 4 and 2 subsamples respectively in order to maintain consistent along-scan and along-track resolutions at, nadir. The SWIR bands, 5-7 and 26, share the same focal-plane array as the 1-km thermal emissive bands, 20-25. During one of the two 500-m subsamples for bands 5-7, sampling of the 1-km bands introduces increased electronic crosstalk contamination, resulting in a subsample difference for both Earth-view and on-board calibrator observations. For this work, we use data from lunar and on-board blackbody observations, which occur at different signal levels for bands 20-25, to derive a correction to the contamination. This correction can be applied to reduce the subsample differences in the MODIS Earth-view data over a wide range of scenes. The impact of this correction on the sensor calibration and Earth-view data will be assessed.