Parametrization of gas transfer velocities and sea-state-dependent wave breaking

Both experimental estimates and different parametrizations of the transfer velocity of poorly soluble gases exhibit a very broad range of values at a given wind speed. Transfer velocities also appear to depend non-linearly on wind speed, and for high wind speeds this non-linearity is widely attributed to the influence of wave breaking. Both theoretical and experimental studies suggest that wave breaking, and associated whitecapping, is not simply dependent on wind speed but depends also on sea state. New parametrizations of gas transfer velocity based on an existing model of the dependence of transfer velocity on wind stress and whitecapping, supplemented by two sea-state-dependent parametrizations of whitecapping, are developed. These new models predict a diversity of transfer velocities at a given wind speed comparable to the diversity of existing parametrizations. Further, the results suggest that some of the existing parametrizations of transfer velocity reflect in part the wind fetch and sea state typical of the experiments used as a basis of the parametrization. It is suggested that transfer velocities may be estimated much more accurately through satellite retrieval of both wind speed and significant wave height than by wind speed alone.