Extending the Satellite Derived Climate DATA Record of Sea Surface Temperature with VIIRS

Abstract:

Sea surface temperature (SST) is an essential variable needed to monitor and understand climate change. The global coverage provided by polar orbiting satellites is seen as the basis of SST climate records (CDRs). Such CDRs require accurate and traceable determination of the uncertainty characteristics of the SST retrievals from the long time series of measurements, taken by a sequence of satellite radiometers of evolving design and capabilities. The most recent of these instruments is the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi-NPP (National Polar-orbiting Partnership). The results of continuing analyses of the first three years of VIIRS measurements of skin SST are presented. The analyses include assessments of the spatial and temporal characteristics of the uncertainties, and comparisons to other satellite-based infrared sensors. VIIRS that has a swath width >3000km is much wider than either the MODIS or AVHRR, offers potentially gap-free coverage between adjacent swaths. However, current algorithms for retrieving SST from the infrared have increased uncertainty, and typically larger cold biases, at higher viewing angles. Alternative algorithmic approaches were developed at Miami to overcome some of the shortcomings identified in operational algorithms and to provide more accurate retrievals across the entire swath width. Additional terms have been added to a VIIRS atmospheric correction algorithm to account for the effects of the high emission angle and long atmospheric path lengths. We conclude that reprocessed VIIRS SSTs using this enhanced algorithm would be capable of improving upon the accuracies of SSTs from the MODIS’s on Terra and Aqua, and AVHRR Pathfinder, and have the potential to contribute to the extension of the satellite-derived Climate Data Records of SST into the future.