System Design Considerations for the Retrieval of Sea Surface Temperatures in the NPOESS Era

Abstract

The National Polar-Orbiting Operational Environmental Satellite System (NPOESS) requires improved accuracy in the retrieval of sea surface skin temperature (SSTS) from its Visible Infrared Imager Radiometer Suite (VIIRS) sensor over the capability to retrieve bulk sea surface temperature (SSTB) that has been demonstrated with currently operational National Oceanic and Atmospheric Administration (NOAA) satellites carrying the Advanced Very High Resolution Radiometer (AVHRR) sensor. Statistics show an existing capability to retrieve SSTB with a 1σ accuracy of about 0.8 K in the daytime and 0.6 K with nighttime data. During the NPOESS era, a minimum 1σ SSTS measurement uncertainty of 0.5 K is required during daytime and nighttime conditions, while 0.1 K is desired. Simulations have been performed, using PACEOS? scene generation software and the multichannel sea surface temperature (MCSST) algorithms developed by NOAA, to better understand the implications of this more stringent requirement on algorithm retrieval methodologies and system design concepts. The results suggest that minimum NPOESS SSTS accuracy requirements may be satisfied with sensor NE?T values of approximately 0.12 K, which are similar to the AVHRR sensor design specifications. However, error analyses of retrieved SSTB from AVHRR imagery suggest that these more stringent NPOESS requirements may be difficult to meet with existing MCSST algorithms. Thus, a more robust algorithm, a new retrieval methodology, or more stringent system characteristics may be needed to satisfy SSTS measurement uncertainty requirements during the NPOESS era. It is concluded that system-level simulations must accurately model all relevant phenomenology and any new algorithm development should be referenced against in situ observations of ocean surface skin temperatures.