A STUDY OF 6 OPERATIONAL SEA-SURFACE TEMPERATURE ANALYSES

This study results from recommendations made by a 1984 WMO Expert Comm ittee on Ocean-Atmosphere Interaction Relevant to Long-Range Forecasti ng. The committee suggested that comparisons be carried out between mo nthly sea surface temperature (SST) analyses routinely made in several different countries in near real time. Emphasis was placed on the imp rovement of such analyses for use in operational long-range forecastin g, especially for initializing dynamical long-range forecasting models . Six different monthly averaged SST analyses have been compared. The extent to which the analyses agree on several space scales and for reg ions covering the global oceans is shown, together with estimates of t he magnitude of various types of errors. Independent estimates of SST obtained from expendable bathythermographs indicate that the monthly m ean Meteorological Office (UKMO), Climate Analysis Center (CAC) in sit u, and CAC blended analyses showed small differences (biases) from the expendable bathythermograph data. The differences were near to or bel ow the margins of statistical significance over the Northern Hemispher e and the Southern Hemisphere tropics. Apparent negative biases in the analyses were noted, however, in the extratropical Southern Hemispher e. The authors finish with a discussion of recent improvements to the accuracy and scope of SST analyses for both long-range forecasting and climate studies. These improvements include an integrated analysis of ice limit, in situ and satellite SST data, and the developing use of optimum interpolation as a method of SST analysis.