Constraining regional fluxes of CO2 and CH4 over Canada by merging atmospheric and ground observations

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Concerns over increases in atmospheric concentrations of greenhouse gases such as CO2 (carbon dioxide) and CH4 (methane) make it critically important to improve understanding of where, why, and at what rates these gases are exchanged between the land surface and the atmosphere. The key gap is our inability to merge observations in the atmosphere and on the ground, characterizing diverse spatio-temporal scales, with process-level biological knowledge. The objectives of this study are as follows: (1) Develop a land-atmosphere modeling system that can ingest both atmospheric and ground-based observations at multiple spatial and temporal scales. (2) Determine the locations, strengths, and reasons for fluxes of CO2 and CH4, the two major greenhouse gases, over Canada. The focus is on resolving regional scale (10~1000 km) fluxes over the continent, knowledge of which have been hampered by modeling systems that cannot interpret the highly varying atmospheric observations over the continent. State-of-the-art atmospheric models will be combined with biospheric models that are optimized against such datastreams as direct CO2/CH4 flux observations and forest inventory analyses, previously used in absence of the atmospheric observations. Thus the proposed modeling system assimilates both atmospheric and ground-based measurements, thereby yielding "best-guess" fluxes that are optimally consistent with both atmospheric and biospheric knowledge. The proposed research program will make steps forward in climate science: a more detailed knowledge of sources/sinks of current greenhouse gases leads to enhanced capability to project future climate. Furthermore, the proposed research program will contribute towards Canada's obligations under the Kyoto Protocol by building the foundation for quantifying and monitoring emissions of greenhouse gases.