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Analysis Description and Recent Reanalysis

Two new high resolution sea surface temperature (SST) analysis products have been developed using optimum interpolation (OI). The analyses have a spatial grid resolution of 0.25° and temporal resolution of 1 day. One product uses Advanced Very High Resolution Radiometer (AVHRR) infrared satellite SST data. The other uses AVHRR and Advanced Microwave Scanning Radiometer (AMSR) on the NASA Earth Observing System satellite SST data. Both products also use in situ data from ships and buoys and include a large-scale adjustment of satellite biases with respect to the in situ data. Two products are needed because there is an increase in signal variance when AMSR became available in June 2002 due to its near all-weather coverage. For both products, the results show improved spatial and temporal resolution compared to previous weekly 1° OI analyses.

The AVHRR-only product uses Pathfinder AVHRR data (currently available from September 1981 through December 2005) and operational AVHRR data for 2006 onwards. Pathfinder AVHRR was chosen, when available, because it agrees better with the in situ data. The AMSR+AVHRR product begins with the start of AMSR data in June 2002. In this product, the primary AVHRR contribution is in regions near land where AMSR is not available. However, in cloud-free regions, use of both infrared and microwave instruments can reduce systematic biases because their error characteristics are independent. A description of the OI analysis can be found in Reynolds, R. W., T. M. Smith, C. Liu, D. B. Chelton, K. S. Casey and M. G. Schlax, 2007: Daily High-resolution Blended Analyses for sea surface temperature. J. Climate, 20, 5473-5496.

OI Diagram