Numerical Modeling of Methane Emissions from Lakes in the Permafrost Zone

A brief review of published observations of methane fluxes to the atmosphere from bogs and lakes in the permafrost zone is presented. Approaches to modeling the emission of methane from bogs are considered, and their advantages and shortcomings, in particular, from the point of view of their coupling to climate models, are outlined. A one-dimensional model developed by the authors for methane generation, transport, and sink in the ground-water body system and coupled to a hydrothermodynamic model of a water body is described. The approaches used in analogous models for bogs as well as new parametrizations describing lake-specific processes are applied. A parametrization of methane generation in vicinity the lower boundary of the thawed ground zone underneath a water body (talik) is suggested. The results of calibrating this model against available observations of methane emission from the thermokarst Shuchi Lake in northeastern Siberia are discussed.