Turbulent air-sea fluxes in the Gulf of Guinea during the AMMA experiment

Abstract

Turbulent fluxes at the air-sea interface were estimated in the framework of the African Monsoon Multidisciplinary Analysis (AMMA) international program. A specific flux measurement mast was designed so as to minimize aerodynamic flow distortion and vibrations. The mast was installed on the research vessel Atalante that cruised in the Gulf of Guinea during the onset of the African monsoon, in June-July 2006. Turbulent fluxes were calculated with an eddy covariance method and with a spectral method. Calculation of eddy correlation fluxes required a correction of flow distortion at turbulent scales, which was performed with a new statistical technique. Application of the spectral flux calculation method revealed that an imbalance term was required, in agreement with results from earlier experiments, and indicated that the value of the Kolmogorov constant (0.55) should not be modified. Bulk exchange coefficients calculated are in good agreement with earlier parameterizations in medium wind conditions. Copyright 2009 by the American Geophysical Union.