Twelve months of data on surface heat fluxes (shortwave radiation, longwave radiation, latent heat and sensible heat, from August 1985 to July 1986), obtained from the European Center for Medium-Range Weather Forecast (ECMWF) on a grid of 1.125¿ latitude by 1.125¿ longitude were analyzed. Comparison with older data from ECMWF (Simonot and Le Treut, 1987) indicates the occurrence of significant improvements in global and local distributions of the fluxes over oceans (mainly the latent and net heat fluxes), except for the shortwave radiative heat flux, which seems degraded. The global mean of the annual net air-sea heat flux is not in equilibrium, but shows a relatively small loss of 5 Wm-2 for the ocean (instead of a 40 Wm-2 gain in an older ECMWF analysis). Meridional oceanic net heat transport is consistent with other climatological estimates (Hastenrath 1982) in the northern hemisphere, but less consistent with estimates from the southern hemisphere. Seasonal variability of the net heat flux at the air-sea interface was studied over two limited mid-latitude ocean basins: the North and the South Atlantic. Annual mean and low frequency rms are discussed.

Fair agreement is found with climatological studies from Bunker (1976, 1988), Esbensen and Kushnir (1981), and Hsiung (1986), with discrepancies being large enough in the tropical South Atlantic to explain the deviation from climatology in the meridional oceanic heat transport in the southern hemisphere. Large-scale variability of low-frequency perturbation net heat flux was investigated by means of empirical orthogonal function (eof) analysis. For each ocean, the first eof accounts for a large amount of the total variance in the data (41% in the North Atlantic and 61% in the South Atlantic), and is characterized by basin-sized oscillations with annual and semiannual cycles. Comparison of our data with a climatology of the Agulhas retroflection area (Walker and Mey, 1988) indicates the good quality of ECMWF analyses in regions where air-sea exchnages are large; but large relative uncertainties remain among estimates in regions where fluxes are weak. ¿ American Geophysical Union 1990