INTERCOMPARISON OF BULK AERODYNAMIC ALGORITHMS FOR THE COMPUTATION OFSEA-SURFACE FLUXES USING TOGA COARE AND TAO DATA

A bulk aerodynamic algorithm is developed for all stability conditions for the computation of ocean surface fluxes. It provides roughness le ngths of wind, humidity, and temperature for a wind speed range from 0 to 18 m s(-1): z(o) = 0.013u(2)/g + 0.11 nu/u* and ln(z(o)/z(ot)) = ln(z(o)/z(oq)) = 2.67Re(1/4) - 2.57 as derived using the Tropical Oce ans Global Atmosphere (TOGA) Coupled Ocean-Atmosphere Response Experim ent (COARE) data constrained by other observations under high wind con ditions. Using the TOGA COARE ship data and the multiyear hourly TOGA Tropical Atmosphere-Ocean moored buoy data, intercomparison of six dif ferent algorithms, which are widely used in research, operational fore casting, and data reanalysis, shows that algorithms differ significant ly in heat and momentum fluxes under both very weak and very strong wi nd conditions, but agree with each other under moderate wind condition s. Algorithms agree better for wind stress than for heat fluxes. Based on past observations, probable deficiencies in roughness lengths (or neutral exchange coefficients) of some of the algorithms are identifie d along with possible solutions, and significant issues (particularly the trend of the neutral exchange coefficient for heat with wind speed under strong wind conditions) are raised for future experiments. The vapor pressure reduction of 2% over saline seawater has a significant impact on the computation of surface latent heat flux under strong win d conditions and should be considered in any bulk aerodynamic algorith m.