Spaceborne Methane Observations by Airs Over Alberta

Methane (CH4) emitted from natural (e.g. wetland) and anthropogenic (e.g. oil and gas industry, and waste management) sources contribute to Alberta's GHG emission. The focus of this study is to examine the spatio-temporal variation of total column CH4 over Alberta, using data from the Atmospheric Infrared Sounder (AIRS) on the EOS/Aqua satellite from 2003 to 2013. Spaceborne measurements by AIRS provide a global view of CH4 distribution in the mid-upper troposphere. This study demonstrates a significant rise of CH4 levels in Alberta in the last ten years. This ascending trend is consistent with the increase of global methane levels in the same time period. Monthly variations indicate a significant increase of CH4 levels in summer with maximum in August, which is probably driven by enhanced convection. Spatial distributions of CH4 reveal a strong west-east gradient with maximum levels in northern regions (55-65 N). The enhanced summer levels over northern and eastern regions suggest possible pathways for CH4 emitted from natural sources (wetlands, lakes and permafrost) in high northern latitude regions and Canadian wetlands (e.g. Hudson Bay wetland). However, the abrupt increase of CH4 concentration coincides with significant change in economic activities during that time period. Since some of the wetland CH4 fluxes are collocated with large anthropogenic source, it is difficult to account for different source contribution. Thus, further studies about CH4 emission and transport over Alberta are recommended to reduce the uncertainties about the natural and anthropogenic contributions of Alberta to Canada's CH4 emissions.