INERTIAL DISSIPATION METHOD APPLIED TO DERIVE TURBULENT FLUXED OVER THE OCEAN DURING THE SURFACE OF THE OCEAN, FLUXES AND INTERACTIONS WITHTHE ATMOSPHERE ATLANTIC STRATOCUMULUS TRANSITION EXPERIMENT (SOFIA ASTEX) AND STRUCTURE-DES-ECHANGES-MER-ATMOSPHERE, PROPRIETES-DES-HETEROGENEITES-OCEANIQUES - RECHERCHE-EXPERIMENTALE (SEMAPHORE) EXPERIMENTS WITH LOW TO MODERATE WIND-SPEED/

The transfer coefficients for momentum and heat have been determined f or 10 m neutral wind speeds (U-10n) between 0 and 12 m/s using data fr om the Surface of the Ocean, Fluxes and Interactions with the Atmosphe re (SOFIA) and Structure des Echanges Mer-Atmosphere, Proprietes des H eterogeneites Oceaniques: Recherche Experimentale (SEMAPHORE) experime nts. The inertial dissipation method was applied to wind and pseudo vi rtual temperature spectra from a sonic anemometer, mounted on a platfo rm (ship) which was moving through the turbulence held. Under unstable conditions the assumptions concerning the turbulent kinetic energy (T KE) budget appeared incorrect. Using a bulk estimate for the stability parameter, Z/L (where Z is the height and L is the Obukhov length), t his resulted in anomalously low drag coefficients compared to neutral conditions. Determining Z/L iteratively, a low rate of convergence was achieved. It was concluded that the divergence of the turbulent trans port of TKE was not negligible under unstable conditions. By minimizin g the dependence of the calculated neutral drag coefficient on stabili ty, this term was estimated at about -0.65Z/L. The resulting turbulent fluxes were then in close agreement with other studies at moderate wi nd speed. The drag and exchange coefficients for low wind speeds were found to be C-en x 10(3) = 2.79U(10n)(-1) + 0.66 (U-10n < 5.2 m/s), C- en x 10(3) = C-hn x 10(3) = 1.2 (U-10n greater than or equal to 5.2 m/ s), and C-dn x 10(3) = 11.7U(10n)(-2) + 0.668 (U-10n < 5.5 m/s), which imply a rapid increase of the coefficient values as the wind decrease d within the smooth flow regime. The frozen turbulence hypothesis and the assumptions of isotropy and an inertial subrange were found to rem ain valid at these low wind speeds for these shipboard measurements. I ncorporation of a free convection parameterization had little effect.