A joint research group led by Dr. Masayuki Kondo, Department of Environmental Geochemical Cycle Research, the Japan Agency for Marine-Earth Science and Technology (JAMSTEC: Asahiko Taira, President) and National Institute for Environmental Studies (NIES: Sumi Akimasa, President) examined consistency between two global terrestrial carbon dioxide (CO2) exchanges based on ground and satellite observation data. It confirmed that using both ground and satellite observations data allows reliable estimation of terrestrial CO2 exchanges at mid and high latitudinal regions in the Northern Hemisphere.
Terrestrial CO2 exchange has usually been evaluated with numerical models that articulate eco-physiological processes of terrestrial carbon cycle based on empirical relations and assumptions. This research was the first attempt to evaluate two different approaches for data-driven terrestrial CO2 exchanges. Specifically, the study group examined how terrestrial CO2 exchange would be consistent between data-driven top-down and bottom-up approaches; the former estimates CO2 exchanges based on atmospheric CO2 concentration measured by the Greenhouse gases Observing SATellite"IBUKI" (GOSAT), and the latter is empirical eddy flux upscaling based on a support vector regression (SVR) model.
As a result, at mid and high latitudinal regions in the Northern Hemisphere, terrestrial CO2 exchanges showed considerable consistency between the two different methods, though large seasonal differences were observed in tropical regions. These differences are likely to be due to lack of sufficient data from ground observation in tropical regions, where estimation of CO2 uptake tends to become higher by the ground-based observation network than that by the GOSAT observations. To estimate terrestrial CO2 exchange more accurately, it suggests that the ground observation network needs to be improved in tropical regions.
In predicting climate changes caused by global warming and other factors, it is important to obtain accurate estimate of the CO2 absorption/emission from land. These research findings can be utilized for such data to improve process models for predicting future climate changes, contributing to higher accuracy of global warming effects.
This research was supported by Environment Research and Technology Development Funds (RFa-1201) from the Ministry of the Environment of Japan and the JAXA Global Change Observation Mission project (grant 115). These study results were posted on the online Journal of Geophysical Research-Biogeosciences by American Geophysical Union on July 15th (JST).
The Greenhouse gases Observing SATellite "IBUKI", developed jointly by the Ministry of the Environment (MOE), the National Institute for Environmental Studies (NIES), and the Japan Aerospace Exploration Agency (JAXA) is the world's only satellite designed specifically to monitor greenhouse gases from space. The satellite has continued to fulfill its main mission in monitoring atmospheric carbon dioxide (CO2) and methane concentrations from space to improve the accuracy of sink/source estimates, and achieve its target to contribute to precision refinement for the ongoing elucidation of carbon cycles, since its launch on January 23, 2009.
CO2 concentrations in mega-cities and their surroundings were analyzed for the three and half years from June 2009 to December 2012, based on the observational data acquired by "IBUKI", indicating the tendency for higher CO2 concentrations in mega-cities than those in their surroundings. Furthermore, positive correlations were shown between differences in CO2 concentrations and the concentrations estimated from data for fossil fuel consumption. These results indicate that "IBUKI" observations have the potential to enable us to detect enhanced CO2 concentrations with their origin in fossil fuel consumption for mega-cities. These studies demonstrate the potential utility of satellite observation of CO2 concentrations as a tool for monitoring greenhouse gas emissions (inventory) from fossil fuels.
With the progress in studies to monitor large point CO2 sources by satellite observation and other methods, these results will be applied to current and forthcoming research projects involving "IBUKI" and its successor - GOSAT-2 - to be launched in 2018.
The Greenhouse gases Observing SATellite "IBUKI" (GOSAT), developed jointly by the Ministry of the Environment (MOE), the National Institute for Environmental Studies (NIES), Japan, and the Japan Aerospace Exploration Agency (JAXA) (hereafter the "Three Parties") is the world's first and only satellite designed specifically to monitor greenhouse gases from space. The satellite has continued to successfully fulfill its main function in monitoring atmospheric carbon dioxide (CO2) and methane (CH4) concentrations from space since it was first launched on January 23, 2009.
Global estimates of the monthly and regional net fluxes of methane (emission and absorption aggregates) were generated for the two years from June 2009 to May 2011, based on both observational data acquired by "IBUKI", and ground-based measurements.
The Greenhouse gases Observing SATellite "IBUKI" (GOSAT), developed jointly by the Ministry of the Environment Japan, the National Institute for Environmental Studies, and the Japan Aerospace Exploration Agency (hereinafter the Three Parties), is the world's first satellite designed specifically for monitoring atmospheric carbon dioxide (CO2) and methane (CH4) from space. The satellite has been in operation since its launch on January 23, 2009.
The Three Parties will now publicly distribute the data of global CO2 fluxes on a monthly and regional basis for the one-year period between June 2009 and May 2010. These flux values were estimated from ground-based CO2 monitoring data and improved GOSAT-based CO2 concentration data.
The Ministry of the Environment Japan, the National Institute for Environmental Studies, and the Japan Aerospace Exploration Agency jointly conduct the GOSAT Project. GOSAT itself was launched on January 23, 2009.
Using observational data from GOSAT and ground-based data, the estimation of monthly regional CO2 sources and sinks (net fluxes) and their uncertainty was carried out. It was demonstrated that the CO2 concentration data retrieved from GOSAT soundings can reduce the uncertainty of fluxes estimated from ground-based data alone.
The outcomes of this research were published in the Meteorological Society of Japan's Scientific Online Letters on the Atmosphere (SOLA) on October 29, 2011. These estimations will now be disseminated to affiliated researchers selected by means of GOSAT Research Announcements. Following the assessment and validation of these results by the researchers, the improved flux data will be made available to the general public.
The Ministry of the Environment, the National Institute for Environmental Studies (NIES), and the Japan Aerospace Exploration Agency (JAXA) have been cooperatively carrying out the Greenhouse gases Observing SATellite (GOSAT) Project. The satellite was placed in orbit on January 23, 2009 and has been collecting data since the following April. With recently completed initial data validation, we have started distributing the results of the observational data analyses (concentrations of carbon dioxide and methane) to general users from February 18, 2010.
The Ministry of the Environment, the National Institute for Environmental Studies, and the Japan Aerospace Exploration Agency are promoting the "IBUKI", Greenhouse gases Observing SATellite (GOSAT, launched in January 23, 2009) project. Recently, an initial analysis of carbon dioxide and methane concentrations was obtained for clear-sky scenes over land. In the future, after further calibration and validation of the data, observation data and corresponding analyzed products will be made available for the registered general public.