The Contribution of GOSAT to Understanding Global GHG Distribution and Estimating Regional Carbon Fluxes Over Its Five-year Operation Period and Future Prospect for Community-wide Collaboration

Abstract:

The Greenhouse gases Observing SATellite (GOSAT) has been operating for more than five-and-a-half years since January 2009. Over that period, the NIES GOSAT Project provided registered researchers and the general public with the retrieved column-averaged concentrations of carbon dioxide (XCO₂) and methane (XCH₄) (SWIR Level 2 data products), which helped ascertain the global distributions of the two global warming gases and their variability with time and space. Further, with those concentration data that filled gaps in the existing surface monitoring networks, the monthly estimates of regional sources and sinks of CO₂ and CH₄ (Level 4 data products) were obtained with smaller uncertainties. Although there are some issues still left that need to be handled, such as region- and time-dependent biases in Level 2 concentrations and low retrieval success rates over the tropics, the GOSAT Project has contributed significantly to advancing the global carbon cycle studies through providing useful space-based GHG data. The Orbiting Carbon Observatory-2 (OCO-2) was launched successfully in July 2014, and now and finally, there are two CO₂ monitoring platforms in space, as originally planned ten years ago. GOSAT is expected to operate and continue its observation for the next several years, even after its five-year nominal operation period ended in early 2014. Evaluating and inter-comparing data from the two platforms will yield valuable findings that can further advance the space-based GHG monitoring techniques. For this to happen, all-community collaboration is needed.

Here, we will present the characteristics of the latest GOSAT data products and some of important research outcomes brought by the GOSAT Research Announcement researchers. We will also show our views on the future of space-based carbon cycle study through close collaboration with worldwide research groups.