Influence of the Presence of Swell on Air-Sea CO2 Transfer Velocity

Abstract

Field measurements at a sea observation tower were made to investigate the dependence of air-sea CO2 transfer velocity on swell conditions. Based on directional wave spectra, we classified swell conditions into three groups, i. e., Pure windsea, Swell-dominated sea and Cross swell. The present data show that the transfer velocity for Pure windsea increases monotonously with the wind speed, while the presence of swell contaminates the wind-speed dependence of the transfer velocity. Also, the transfer velocity for Cross swell seems to take larger values than the other conditions. Moreover, we examined how the transfer velocity nondimensionalized by the friction velocity depends on a nondimensional wave-energy dissipation rate. In such relations, there is no remarkable difference in three types of swell conditions. This means that the energy dissipation rate may be effective for the parameterization of the transfer velocity.