NPP VIIRS Day-Night Band Stray Light Characterization and Correction Using Calibration View Data

Abstract:

The NPP VIIRS Day-Night Band (DNB) nighttime imagery quality is affected by stray light contamination. In this study, we examined the relationship between the observed stray light and the signals in VIIRS’s calibrators to investigate the potential stray light source and sneak paths. The stray light contamination is found to be highly correlated with calibrator signal characteristics and the stray light origin and paths could vary at satellite’s orbital location and time. For the observed high latitude stray light regions, the calibration view data showed signal profiles that are similar to the estimated earth scene stray light profiles. In the twilight region, calibration view signal profiles can be used to extend stray light estimates to improve upon the current extrapolation method. The calibration view data can also be used to identify the additional stray light occurred during southern hemisphere spring time and the occasional low latitude stray light contamination. Based on the calibration view data, the expected earth scene dark signals can be approximated by extending signals from un-contaminated regions to estimate the additional stray light. Applying this updated stray light correction method, the DNB images showed expected earth scene features over the additional southern hemisphere stray light region, although some residual effects remained. Our analysis indicates that the DNB calibration view data can be used to improve DNB stray light characterization and correction. As stray light affects significant portion of nighttime scenes, further refinement in characterization and correction is important to ensure VIIRS DNB imagery quality in NPP and future missions.