Overview of the NOAA/NASA advanced very high resolution radiometer Pathfinder algorithm for sea surface temperature and associated matchup database

The National Oceanic and Atmospheric Administration (NOAA)/NASA Oceans Path finder sea surface temperature (SST) data are derived from measurements mad e by the advanced very high resolution radiometers (AVHRRs) on board the NO AA 7, 9, 11, and 14 polar orbiting satellites. All versions of the Pathfind er SST algorithm are based on the NOAA/National Environmental Satellite Dat a and Information Service nonlinear SST operational algorithm (NLSST). Impr ovements to the NLSST operational algorithm developed by the Pathfinder pro gram include the use of monthly calibration coefficients selected on the ba sis of channel brightness temperature difference (T-4 - T-5). This channel difference is used as a proxy for water vapor regime. The latest version (v ersion 4.2) of the Pathfinder processing includes the use of decision trees to determine objectively pixel cloud contamination and quality level (0-7) of the SST retrieval. The 1985-1998 series of AVHRR global measurements ha s been reprocessed using the Pathfinder version 4.2 processing protocol and is available at various temporal and spatial resolutions from NASA's Jet P ropulsion Laboratory Distributed Active Archive Center. One of the highligh ts of the Pathfinder program is that in addition to the daily global area c overage fields, a matchup database of coincident in situ buoy and satellite SST observations also is made available for independent algorithm developm ent and validation.