Gas transfer at water surfaces
ABSTRACT: The exchange of inert and sparingly soluble gases including carbon dioxide, methane, and oxygen between the atmosphere and oceans is controlled by a thin 20-200 μm thick mass boundary sublayer at the top of the ocean. The hydrodynamics in this layer is significantly different from boundary layers at rigid walls since the orbital motion of the waves is of the same order as the velocities in the viscous boundary layer. Therefore there is no simple analogy between momentum and mass transfer. Starting with the knowledge available at the first International Symposium on “Gas Transfer at Water Surfaces” in 1983 at Cornell University, co-initiated by Gerhard Jirka, the parameters controlling air-sea gas transfer are discussed. Then it will be shown how in the wake of this symposium novel imaging techniques gradually evolved, which give direct insight into the mechanisms of the transfer processes at the air-water interface.