Impacts of in situ and additional satellite data on the accuracy of a sea-surface temperature analysis for climate

Additional in situ and satellite data improve the accuracy of a blended (in situ and satellite) sea-surface temperature (SST) analysis using optimum interpolation (01). Two studies were conducted to evaluate the impacts of in situ and additional satellite data. One study evaluated the adequacy of the recent in situ network. Because of the high coverage of satellite data, in situ data used in the analysis tends to be overwhelmed by satellite data. Thus, the most important role of the in situ data in the analysis is to correct large-scale satellite biases. Simulations with different buoy densities showed the need for at least two buoys on a 10 degrees spatial grid. This will ensure that satellite biases do not exceed 0.5 degrees C. Using this criterion, regions were identified where additional buoys are needed. A second study evaluated the impact of satellite SST retrievals from the tropical rainfall measuring mission microwave imager (TMI) on the 01 analysis. The present version only uses infrared satellite data from the advanced very high resolution radiometer (AVHRR) instrument. The results of the intercomparisons showed that both AVHRR and TMI data have biases that must be corrected for climate studies. The addition of TMI data clearly improved the 01 analysis accuracy without bias correction, but was less significant when bias correction was used. However, there are areas of the ocean with limited in situ data and restricted AVHRR coverage due to cloud cover, and the use of both TMI and AVHRR should improve the accuracy of the analysis in those areas. Copyright (c) 2005 Royal Meteorological Society.