Abstract
VIIRS (Visible-Infrared Imaging Radiometer Suite) instrument onboard the Suomi NPP (National Polar-orbiting Partnership) spacecraft has been operating on orbit for more than three years by now. Throughout this time temperature of the VIIRS cold FPA (focal plane array) has remained remarkably stable near 80 K. Two exceptions when elevated cold FPA temperatures were observed were the period before complete activation of the cryo-cooler and the brief time during an orbital pitch maneuver. Dependence of the VIIRS TEB (thermal emissive band) noise on the cold FPA temperature was measured using onboard calibrator data acquired during these occurrences. The on-orbit measurements have enabled prediction that if the cold FPA temperature were to increase from 80 K to 82 K, noise in the VIIRS LWIR (long-wave infrared) bands, M14, M15, M16, and I5, would increase by approximately 20%. Since large margins exist between the current VIIRS TEB noise performance and the product requirements, such an increase, although not negligible, would still be acceptable for measurements of sea surface temperature and cloud top properties. Nevertheless, it will be beneficial if the VIIRS cold FPA temperature remains unchanged for the next several years of the Suomi NPP mission.
On-orbit Characterization of the Dependence of VIIRS Thermal Bands Noise on Cold FPA Temperature
VIIRS (Visible-Infrared Imaging Radiometer Suite) instrument onboard the Suomi NPP (National Polar-orbiting Partnership) spacecraft has been operating on orbit for more than three years by now. Throughout this time temperature of the VIIRS cold FPA (focal plane array) has remained remarkably stable near 80 K. Two exceptions when elevated cold FPA temperatures were observed were the period before complete activation of the cryo-cooler and the brief time during an orbital pitch maneuver. Dependence of the VIIRS TEB (thermal emissive band) noise on the cold FPA temperature was measured using onboard calibrator data acquired during these occurrences. The on-orbit measurements have enabled prediction that if the cold FPA temperature were to increase from 80 K to 82 K, noise in the VIIRS LWIR (long-wave infrared) bands, M14, M15, M16, and I5, would increase by approximately 20%. Since large margins exist between the current VIIRS TEB noise performance and the product requirements, such an increase, although not negligible, would still be acceptable for measurements of sea surface temperature and cloud top properties. Nevertheless, it will be beneficial if the VIIRS cold FPA temperature remains unchanged for the next several years of the Suomi NPP mission.