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

Abstract

Both experimental estimates and different parametrizations of the transfer velocity of poorly soluble gases exhibit avery 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 andexperimental studies suggest thatwave breaking, and associated whitecapping, is not simply dependent on wind speed butdepends also on sea state. New parametrizations of gas transfer velocity based on an existing model of the dependenceof transfer velocity on wind stress and whitecapping, supplemented by two sea-state-dependent parametrizations ofwhitecapping, are developed. These newmodels predict a diversity of transfer velocities at a given wind speed comparableto the diversity of existing parametrizations. Further, the results suggest that some of the existing parametrizations oftransfer 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 windspeed and significant wave height than by wind speed alone.