Gas exchange across the air—sea interface

Abstract

The physics of gas exchange at the air-sea interface are reviewed. In order to describe the transfer of gases in the liquid near the boundary, a molecular plus eddy diffusivity concept is used, which has been found useful for smooth flow over solid surfaces. From consideration of the boundary conditions a similar dependence of eddy diffusivity on distance from the interface can be derived for the flow beneath a gashiquid interface, at least in the absence of waves. The influence of waves is then discussed. It is evident from scale considerations that the effect of gravity waves is small. It is known from wind tunnel work that capillary waves enhance gas transfer considerably. The existing hypotheses are apparently not sufficient to explain the observations. Examination of field data is even more frustrating since the data do not show the expected increase of gas exchange with wind speed.

Distribution of chlorophenolics in a marine environment

“…The effects of the wind stress and the surface film thickness are difficult to estimate, and the air-sea exchange under natural conditions is not fully understood. The difficulties of modeling the air-sea exchange are discussed and demonstrated by Hasse and Liss (44) and by Holmen and Liss (45).…”

Effect of wind waves on air-sea gas exchange: proposal of an overall CO2 transfer velocity formula as a function of breaking-wave parameter

“…In contrast to the spectacular increase of gas exchange with wind speed observed in wind tunnels, the earlier field data come mainly from radon evasion measurements (Peng et al, 1979) that show no increase of gas transfer rate with wind speed. As pointed out by Hasse and Liss (1980), it seems physically unrealistic to find little or no effect of wind speed on the rate of gas transfer when all the wind tunnel studies show clear positive relationships. Deacon (1981) attempted to reconcile the two data sets by filtering the field data on the basis of wind dependence.…”

Chemistry and Release of Gases from the Surface Ocean

“…Rigid boundary or solid wall models apply a velocity profile to either side of the interface to describe a smooth transition between diffusive and turbulent regimes . In such models, turbulence plays a modest role in controlling the rate of transfer.…”