Mitigating JPSS J1 VIIRS DNB Performance Shortfalls with Expanded Cal/Val

Abstract:

The outstanding performance of the Suomi NPP VIIRS Day/Night Band(DNB) has enables a number of new nocturnal applications under lunar illumination, as well as the detection of anthropogenic and natural low light sources. In addition, its operational use at the National Weather Service in Alaska allows the DNB to be promoted to the key product parameter (KPP) status. This also raises expectations for future VIIRS models. For JPSS J1 VIIRS DNB, performance shortfalls have been identified based on prelaunch tests in the laboratory. This includes the nonlinear response at high scan angles, and the straylight contamination that persists on Suomi NPP VIIRS will likely to appear for J1 as well. This paper introduces the mitigation strategies to address these performance shortfalls. The new aggregation mode options and artifacts in imagery are discussed. Modifications to the geolocation software code has been developed to accommodate the changes. The new aggregation mode also introduces J1 specific characteristics in the DNB imagery.

Expanded validation capabilities have been developed using Suomi NPP data as proxy to monitor the response versus scan both radiometrically and in geolocation accuracy. This includes the radiometric stability monitoring using night light point sources such as from bridges, oil platforms, power plants, as well as flares. Time series of VIIRS observations of the point sources at different scan angles are constructed to monitor the radiometric bias and geolocation across aggregation zones. Finally, lessons learned in the straylight correction for Suomi NPP can be applied to J1 VIIRS DNB to ensure that the performance meet specifications and user expectations.