Geo-Leo intercalibration to evaluate the radiometric performance of NOAA-20 VIIRS and GOES-16 ABI

With more than seven years in space, S-NPP VIIRS has been rigorously calibrated and validated. The global coverage of VIIRS has been doubled after the launch of NOAA-20 in November 2017. Since no direct SNO exist between SNPP and NOAA-20, radiometric consistency between VIIRS sensors onboard these satellites can be quantified through double differencing. This study performs geo-leo interccomparison using SNOs between GOES16 ABI and VIIRS instruments. A past study suggested that NOAA-20 VIIRS has nearly -2% bias relative to S-NPP for most of the VNIR bands. Similarly, GOES-16 ABI comparison with S-NPP VIIRS using field campaign data over Sonoran desert in the past indicated a large discrepancy (more than 6%) for ABI band 2 (0.86 μm). This paper attempts to fulfill two major purposes, one is to evaluate the temporal radiometric consistency between VIIRS and ABI and the other is to quantify the radiometric consistency between the two VIIRS instruments through double differencing using ABI as a reference. SNOs over the ocean are analyzed to quantify the bias for both NOAA-20 VIIRS and ABI relative to S-NPP using ray matching technique. The impact on bias due to spectral differences will be corrected using spectral band adjustment factors estimated using hyperspectral measurements from instruments such as Sciamachy.