Methane Fluxes in West Siberia: 3-D Regional Model Simulation

The West Siberian region is one of the main contributors of the atmospheric greenhouse gas methane due to the large areas of wetlands, rivers, lakes and numerous gas deposits situated there. But there are no reliable estimations of integral methane flux from this area into the atmosphere. For assessment of methane fluxes in West Siberia the specially constructed 3-D regional chemical transport model was applied. The 3-D distribution of methane is calculated on the basis of the current meteorological data fields (wind, temperature, geopotential) updated 4 times a day. The methane concentrations measured near the main gas fields of West Siberia in the summer season of 1999, were used for correction of methane flux intensity estimates obtained previously by comparison of measurements carried out in summer 1993 and 1996 with modelled methane mixing ratio distribution. This set of field and model experiments confirmed the preliminary conclusion about low leakage intensity: anthropogenic methane flux does not exceed 5-15% of total summer methane flux, estimated as 11-12 Mt CH sub(4) in summer from this region, in spite of the large areas of gas deposits located there.