発表論文

Inverse modeling of CO2 fluxes using GOSAT data and multi-year ground-based observations

著者
Saeki T., Maksyutov S., Saito M., Valsala V., Oda T., Andres R. J., Belikov D., Tans P., Dlugokencky E., Yoshida Y., Morino I., Uchino O., Yokota T.
雑誌名
SOLA, 9, 45-50
DOI
10.2151/sola2013-011
概要
We present surface CO2 flux estimates obtained by an inverse modeling analysis from column-averaged dry air mole fractions of CO2 (XCO2) observed by the Greenhouse gases Observing SATellite (GOSAT) and ground-based data. Two inversion cases were examined: 1) a decadal inversion using ground-based CO2 observations by NOAA from 1999 to 2010 to derive CO2 flux interannual variability, and 2) an inversion using NOAA plus NIES GOSAT XCO2 data from June 2009 to October 2010. We used single-shot GOSAT data and individual NOAA flask data for the inversions. Our results show differences in estimated fluxes between the NOAA data inversion and the NOAA plus GOSAT data inversion, especially in Northern Eurasia and in Equatorial Africa and America where the ground-based observational sites were sparse. Uncertainty reduction rates of 40%–70% were achieved by inclusion of GOSAT data, compared to the case using just the NOAA data. The inclusion of GOSAT data in the inversion resulted in larger summer sinks in northwest Boreal Eurasia and a smaller summer sink in southeast Boreal Eurasia, with a clear uncertainty reduction in both regions. Adding GOSAT data also led to increase in Tropical African fluxes in boreal winter beyond interannual variability from NOAA data inversions.
温室効果ガス観測技術衛星GOSATから得られたXCO2と複数年の地上データを用いて炭素収支推定を行った。その結果、地上観測の空白域である北方ユーラシア、赤道アフリカ、南アメリカ等で、推定フラックスの不確実性が大幅に減少し、さらに推定フラックスも過去10年の炭素収支と異なる結果が得られることがわかった。