Detecting the radiometric changes of FY-3A/MERSI reflective solar bands by use of stable desert sites

To monitor changes in sensor performance and sensor calibration is a critical step to ensure data quality and to meet the needs of quantitative remote sensing in a broad range of scientific applications. One of the least expensive and increasingly popular methods of on-orbit calibration has been the use of large-area stable terrestrial sites. In this study, three stable desert sites of Libya-1, Sonora, and Arabia-2 are used to assessment the radiometric changes of reflective solar bands of FY-3A/MERSI from May 2008 to Dec. 2013. For each site, two BRDF models are established using the TOA reflectance measurements in the winter half-year and summer half-year late in the mission. Then, the degradation rates of RSBs of MERSI are predicted using an exponential fit of the BRDF-corrected time series. Results show that the use of two BRDF models is effective to removal of seasonal oscillation caused by angular effects. Degradation rates from three desert sites are in good agreement, with the standard deviation less than 1.5% for most of the bands. When compared with the DCC method, consistent detecting results are found, and the absolute deviation is less than 3% for most of the channels.