Sensitivity of the model of methane emission from the Arctic shelf seas to the parameterization of the gas exchange process
V.V. Malakhova, M.V. Kraineva
Institute of Computational Mathematics and Mathematical Geophysics of the Siberian Branch of the RAS, Novosibirsk, Russia
Keywords: methane emission, dissolved methane transport, gas exchange, Arctic, numerical simulation
Abstract
There is considerable uncertainty about the methane emission from the Arctic shelf seas. Methane fluxes in this region can be underestimated and play a significant role due to the large volume of gas contained in bottom sediments in the permafrost and gas hydrates. We have analyzed the model sensitivity to the parametrization of gas exchange processes on the sea surface. The study is based on the numerical modeling results of the transport of dissolved methane in the seas of the Arctic. The dissolved methane transport model is included in the basic model of the ocean and sea ice developed at the Institute of Computational Mathematics and Mathematics, Siberian Branch, Russian Academy of Sciences. Estimates of methane emissions into the atmosphere were made with various parametrization of the gas exchange process in the "water - atmosphere" and "water - ice - atmosphere" systems using NCEP/NCAR reanalysis data. The uncertainty of the estimate of annual methane emission amounted to 6-12% when considering different dependencies of gas exchange on wind. The scheme accounting the ice cover has a more pronounced influence on the flux: the uncertainty increased to 50-130%. Parameterization of the relationship between ice cover and gas exchange can have a great influence on the calculated methane fluxes and lead to underestimation of its emission from the seas of the Arctic shelf.
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