Effect of Langmuir cells on bubble dissolution and air‐sea gas exchange

Abstract

Gases are exchanged between the atmosphere and ocean by diffusion through the sea surface and by dissolution of air bubbles injected by breaking wind waves. Langmuir cells enhance the contribution from bubbles by keeping them under water for longer thus increasing their dissolution. We determine the importance of Langmuir cells by using a bubble model to calculate the amount of gas that dissolves from bubbles as a function of wind speed, gas saturation, and injection depth and a Langmuir cell model to estimate the effect of the associated downwelling currents on bubble dissolution. The calculations are preformed for the eight gases N2, O2, CO2, He, Ne, Ar, Kr, and Xe, and the results are then compared with the total gas exchange determined by common descriptions of air‐sea gas exchange. The contribution of gas bubbles to air‐sea gas exchange increases with wind speed and can reach 77% for O2, 98% for N2, and 16% for CO2 at a wind speed of 20 m s−1 and a gas saturation of 95%. The additional effect of Langmuir cells on the total gas exchange at a gas saturation of 95% is 19% for O2, 35% for N2, and 0.7% for CO2. The importance of Langmuir cells for air‐sea gas exchange generally increases with gas saturation and decreases with the solubility of the gas.