Rachel H. R. Stanley William J. Jenkins Dempsey E. Lott, III Scott C. Doney, Noble gas constraints on air-sea gas exchange and bubble fluxes, Journal of Geophysical Research: Oceans, submitted
Air-sea gas exchange is an important part of the biogeochemical cycles of many climatically and biologically relevant gases including CO2, O2, dimethyl sulfide and CH4. Here we use a three year observational time-series of five noble gases (He, Ne, Ar, Kr, and Xe) at the Bermuda Atlantic Time-series Study (BATS) site in tandem with a one-dimensional upper-ocean model to develop an improved parameterization for air-sea gas exchange that explicitly includes separate components for diffusive gas exchange and bubble processes. Based on seasonal time-scale noble gas data, this parameterization, which has a 1s uncertainty of ±14% for diffusive gas exchange and ±29% for bubble fluxes, is more tightly constrained than previous parameterizations. Although the magnitude of diffusive gas exchange is within errors of that of Wanninkhof [1992], a commonly used parameterization, we find that bubble-mediated exchange, which is not explicitly included in Wanninkhof [1992] or many other formulations, is significant even for soluble gases. If one uses observed saturation anomalies of Ar (a gas with similar characteristics to O2) and a parameterization of gas exchange to calculate gas exchange fluxes, then the calculated fluxes differ by ~ 240% if using parameterization presented here compared to using the Wanninkhof [1992] parameterization. If instead one includes the gas exchange parameterization in a model, then the calculated fluxes differ by ~ 35% between using this parameterization and that of Wanninkhof [1992]. These differences suggest that the bubble component should be explicitly included in a range of marine biogeochemical calculations that incorporate air-sea gas fluxes.
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