SHIP-BOARD MEASUREMENTS AND ESTIMATIONS OF AIR-SEA FLUXES IN THE WESTERN TROPICAL PACIFIC DURING TOGA COARE

Direct air-sea flux measurements were made on RN Kexue #1 at 40 degree s S, 156 degrees E during the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean-Atmospheric Response Experiment (COARE) Intensive Observ ation Period (IOP). An array of six accelerometers was used to measure the motion of the anchored ship, and a sonic anemometer and Lyman-alp ha hygrometer were used to measure the turbulent wind vector and speci fic humidity. The contamination of the turbulent wind components by sh ip motion was largely removed by an improvement of a procedure due to Shao based on the acceleration signals. The scheme of the wind correct ion for ship motion is briefly outlined. Results are presented from da ta for the best wind direction relative to the ship to minimize flow d istortion effects. Both the time series and the power spectra of the s onic-measured wind components show swell-induced ship motion contamina tion, which is largely removed by the accelerometer correction scheme, There was less contamination in the longitudinal wind component than in the vertical and transverse components. The spectral characteristic s of the surface-layer turbulence properties are compared with those f rom previous land and ocean results, Momentum and latent heat fluxes w ere calculated by eddy correlation and compared to those estimated by the inertial dissipation method and the TOGA COARE bulk formula. The e stimations of wind stress determined by eddy correlation are smaller t han those from the TOGA COARE bulk formula, especially for higher wind speeds, while those from the bulk formula and inertial dissipation te chnique are generally in agreement. The estimations of latent heal flu x from the three different methods are in reasonable agreement. The ef fect of the correction for ship motion on latent heat fluxes is not as large as on momentum fluxes.