Analysis of calibration difference between MODIS and MISR

Abstract

MODIS and MISR are two Earth Observing System instruments flown onboard Terra satellite. Their synergistic use could greatly benefit the broad user community by ensuring the global view of the Earth with high-quality products. A necessary condition for data fusion is radiometric calibration agreement between the two instruments. Earlier studies showed about 3% absolute radiometric difference between MISR and respective MODIS land bands in the visible and near-IR spectrum, which are also used in aerosol and cloud research. This study found a systematic bias of +(0.01-0.03) between two surface albedo products derived from MODIS and MISR L1B data using the AERONET-based Surface Reflectance Validation Network (ASRVN). The primary cause of the bias is inconsistencies in the cross-sensor calibration. To characterize MODIS-MISR calibration difference, top-of-atmosphere MODIS and MISR reflectances were regressed against each other over liquid water clouds. The empirical regression results have been adjusted for the differences in the respective MISR and MODIS spectral responses using radiative transfer simulations. The MISR-MODIS band gain differences estimated with this technique are +6.0% in the blue, +3.3% in the green, +2.7% in the red, and +0.8% in the NIR band. About 2.1%-3.6% of the difference in the blue band is due to the difference in the MODIS-MISR solar irradiance models.