Estimation of methane emission from West Siberian Lowland with sub-pixel land cover characterization

The West Siberian Lowland (WSL) is the world´s largest high-latitude wetland covering nearly 2/3 of western Siberia. At least half of this area consists of peatlands, which sequester atmospheric carbon in the form of undecomposed plant matter and it is presumed to be a source of methane gas. In this paper, firstly, an ASTER image near Noyabrsk mire was used to map six wetland ecosystems (red pine, white birch, bog, palsa, open water and bare soil) supplemented by field observation. Then spectral linear mixture analysis was performed between MODIS and ASTER data acquired on the same day. Secondly, field observations were scaled up with these different spatial resolution satellite data. Each of the wetland ecosystem coverage ratio in sub-pixel level was provided by the spectral linear mixture analysis. Field observation shows that the mean rate of CH₄ emission from bog and open water averaged 5.246 and 1.081 (mg CH₄ m^-2 h^-1) respectively. The methane emission from the area was estimated by multiplying these average methane emission rate and the area percentage of bog and open water in each pixel. Finally, the mean methane emission over MODIS coverage was estimated to be 1.864×10⁹ g CH₄ day^-1.