Arctic regions are especially influenced by a warming climate and thus are of high scientific interest. Methane, a highly radiative active trace gas and hence affecting global warming, is produced in permafrost soils and released into the atmosphere. The Lena River Delta, located at the Laptev Sea in northeast Siberia, is characterized by arctic tundra ecosystems and is underlain by continuous permafrost. Modelling methane flux is an important step in determining its source strength in high arctic environments.We present a methodical structure wherein two models are coupled and used to assess methane emissions from permafrost soils in the Lena River Delta on the regional scale. The process-based vegetation model BETHY/DLR (Biosphere Energy Transfer Hydrology Model; Knorr 1997, Wisskirchen 2005) is applied to calculate the net primary productivity (NPP) of high arctic tundra vegetation. NPP is parameterised as a measure for substrate availability and thus an important input parameter for the second model: the process-based methane model (Walter 1998) is subsequently used to explicitly model methane emissions for a given soil column, taking into account thawing permafrost.Model forcing consists of meteorological data, e.g. radiation, air and soil temperature and precipitation, obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF). They are validated by field measurements. Auxiliary input data for both models are derived from satellite-borne remote sensing data. A land use/land classification (LULC) scheme based on multispectral LANDSAT-7 ETM+ data (Schneider 2005) is used to derive information on wetland distribution as well as on vegetation and active layer thickness (ALT). The three parameters are key factors in modelling methane emissions from permafrost affected tundra ecosystems.Various measurements of methane flux on the landscape scale and small scale have been carried out during the entire growing season 2006 in the southern part of the Lena River delta (72°N, 126°E) by Alfred Wegener Institute for Polar and Marine Research (Sachs et al. 2007). The data were used to validate presented model results.
AWI Organizations > Geosciences > Junior Research Group: Permafrost