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Regional CO2 flux estimates for 2009-2010 based on GOSAT and ground-based CO2 observations

Maksyutov, S and Takagi, H and Valsala, VK and Saito, M and Oda, T and Saeki, T and Belikov, DA and Saito, R and Ito, A and Yoshida, Y and Morino, I and Uchino, O and Andres, RJ and Yokota, T (2013) Regional CO2 flux estimates for 2009-2010 based on GOSAT and ground-based CO2 observations. Atmospheric Chemistry and Physics, 13 (18). pp. 9351-9373.

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We present the application of a global carbon cycle modeling system to the estimation of monthly regional CO2 fluxes from the column-averaged mole fractions of CO2 (XCO2) retrieved from spectral observations made by the Greenhouse gases Observing SATellite (GOSAT). The regional flux estimates are to be publicly disseminated as the GOSAT Level 4 data product. The forward modeling components of the system include an atmospheric tracer transport model, an anthropogenic emissions inventory, a terrestrial biosphere exchange model, and an oceanic flux model. The atmospheric tracer transport was simulated using isentropic coordinates in the stratosphere and was tuned to reproduce the age of air. We used a fossil fuel emission inventory based on large point source data and observations of nighttime lights. The terrestrial biospheric model was optimized by fitting model parameters to observed atmospheric CO2 seasonal cycle, net primary production data, and a biomass distribution map. The oceanic surface pCO2 distribution was estimated with a 4-D variational data assimilation system based on reanalyzed ocean currents. Monthly CO2 fluxes of 64 sub-continental regions, between June 2009 and May 2010, were estimated from GOSAT FTS SWIR Level 2 XCO2 retrievals (ver. 02.00) gridded to 5° � 5° cells and averaged on a monthly basis and monthly-mean GLOBALVIEW-CO2 data. Our result indicated that adding the GOSAT XCO2 retrievals to the GLOBALVIEW data in the flux estimation brings changes to fluxes of tropics and other remote regions where the surface-based data are sparse. The uncertainties of these remote fluxes were reduced by as much as 60 through such addition. Optimized fluxes estimated for many of these regions, were brought closer to the prior fluxes by the addition of the GOSAT retrievals. In most of the regions and seasons considered here, the estimated fluxes fell within the range of natural flux variabilities estimated with the component models.

Item Type: Article
Additional Information: Copyrights of this article belongs to the Authors.
Uncontrolled Keywords: atmospheric chemistry; carbon dioxide; carbon flux; emission inventory; GOSAT; marine atmosphere; observational method; oceanic current; stratosphere; tracer; transport process
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 19 Jun 2014 10:34
Last Modified: 19 Jun 2014 10:34

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