An inverse approach to estimate bubble-mediated air-sea gas flux from inert gas measurements

An ocean general circulation model (oGCM) was used in concert with a global database of inert gas measurements (Ne, Ar, N2/Ar and Kr/Ar) to constrain the magnitude of bubble mediated air-sea gas flux. We illustrate the inverse method using a simple bubble model that includes two end member types of bubbles: small bubbles that completely dissolve, and larger bubbles that briefly are submerged and exchange gases with seawater. An inverse solution to the oGCM constrains the flux contribution for bubbles that completely dissolve as a function of wind speed. Our results indicate air injection values at high wind speeds (> 10 m s) that fall between two previous estimates which differ by a factor of three. Future improvements of the method demonstrated here but including seasonality should allow for better constraints on bubble mediated gas exchange as well as the ability to test the performance of a range of bubble models.