Comparing Mass, Momentum and Air-Sea CO2 Fluxes for the North Atlantic and the European Arctic Using Different Parametrizations Dependent on Wind Speed

The standard way of parametrizing fluxes in circulation models is by using wind speed (U10), a parameter available both in models with an active atmosphere and in reanalyses. There are also several wind speed climatologies which can be used for calculating regional or global mass, momentum and energy fluxes. Those climatologies are also used in calculating the air-sea CO2 flux where is still a lot of open question on carbon sinks, especially for the northern hemisphere as well as strong wind. However, the very functions used to calculate fluxes from winds have evolved over time and still have large differences (especially in the case of aerosol source function).

We have chosen the European Arctic mostly because of the interesting part in air-sea interaction (six-monthly cycle, strong wind and ice cover) but there is not a lot of data so we have chosen the North Atlantic as the region of high coverage with measurements which can be used to compare with the calculated fluxes with measurement data. An additional reason was the importance of the area for the North Hemisphere climate, and especially for Europe. The study is related to an ESA funded OceanFlux GHG Evolution project and is meant to be part of a PhD thesis (of I.W) funded by Centre of Polar Studies "POLAR-KNOW" (a project of the Polish Ministry of Science).

We have used a modified version FluxEngine, a tool created within an earlier ESA funded project (OceanFlux Greenhouse Gases) for calculating trace gas fluxes to derive two purely wind driven (at least in the simplified form used in their parameterizations) fluxes. The modifications included removing gas transfer velocity formula and replacing it with the respective formulas for momentum transfer and mass (aerosol production) while using the wind parameterizations and interpolation procedures used in FluxEngine to integrate fluxes over a region. This allowed us to develop quickly a tool where different parameterizations of drag coefficient and aerosol source function could be tested and the resulting monthly and annual fluxes compared.