Maintaining SNPP VIIRS Reflective Solar Band Sensor Data Record Quality: On-Orbit Update of Screen Transmission and Solar Diffuser BRDF Parameters

The Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi National Polar Orbiting Partnership (SNPP) satellite collects radiometric and imagery data in 22 spectral bands within the visible and infrared region ranging from 0.4 to 12.5 um. These data are calibrated and geolocated in ground processing to generate Sensor Data Records (SDRs). This presentation addresses maintenance of reflective solar band (RSB) calibration through on-orbit update of screen transmission and solar diffuser (SD) bidirectional reflectance distribution function (BRDF) parameters that are used in calculating RSB calibration correction factors. These parameters are derived from a combination of satellite yaw maneuver data collected in February 2012 as well as approximately two years of mission data. The update method is designed to be adaptive to the aging of the instrument and associated physical changes in the screen transmission and SD BRDF, as it can be applied to any portion of the mission data of sufficient duration to cover the required range of SD solar illumination geometries or to all of the available mission data. The update method is also robust to variations in the functional forms used to fit SD BRDF degradation over time. The updated screen transmission and SD BRDF parameters are shown to provide improved RSB SDR quality through elimination or reduction of unphysical artifacts in the calibration correction factors throughout the mission to date, not just for the portion of the mission used to provide data for generating the update.