Analysis of Suomi–NPP VIIRS vignetting functions based on yaw maneuver data

摘要: The Suomi – NPP Visible Infrared Imager Radiometer Suite (VIIRS) reflective bands are calibrated on-orbit via reference to regular solar observations through a attenuation screen (SAS) and diffusely reflected off a Spectralon ® panel. degradation of the Spectralon panel BRDF due UV exposure is tracked via ratioing radiometer (SDSM) which compares near simultaneous with direct the sun (through separate screen). On-orbit, vignetting functions both screens are most easily measured when satellite performs series yaw maneuvers over short period time (thereby covering yearly angular variation in couple days). Because SAS fixed, only the product transmission was measured. Moreover, this product measured by VIIRS detectors as well SDSM (albeit at different reflectance angles Spectralon panel). also fixed; case, directly. Corrections for instrument drift degradation, geometry, spectral effects were taken into consideration. The resulting then compared pre-launch measurements models based on screen geometry.