MODELLING METHANE EMISSIONS FROM SIBERIAN HIGH ARCTIC ENVIRONMENTS – A CASE STUDY FOR THE LENA RIVER DELTA REGION

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 thawing 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 during the vegetation period is an important step in determining its source strength in high arctic environments. A methodical structure is presented wherein two models are coupled and used to assess methane emissions from permafrost soils in the Lena River Delta. The process-based vegetation model BETHY/DLR (Biosphere Energy Transfer Hydrology Model [9, 26]) is applied to calculate net primary productivity (NPP) which is an important input parameter for the process-based methane model [23] explicitly modelling methane emissions for a given soil column, taking into account thawing permafrost. Model forcing consists of meteorological data obtained from in situ measurements and from the European Centre for Medium Range Weather Forecasts (ECMWF). Auxiliary input data for both models are derived from field observations as well as from Medium Resolution Imaging Spectrometer (MERIS) data. MERIS Full Resolution (FR) images have been acquired for the growing season of 2006 within the ESA-AO 3909 and used to derive time series of Leaf Area Index (LAI). A land classification scheme based on MERIS-FR data will be used to model methane emissions for the Lena Delta on the regional scale. Various measurements of methane flux on the landscape scale and small scale have been carried out in the southern part of the Lena River Delta (72°N, 126°E) by Alfred Wegener Institute for Polar and Marine Research. The data were used to validate model results