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- Title
Atmospheric carbon dioxide and methane measured by GOSAT and GOSAT-2.
- Authors
Yoshida, Yukio; Oshio, Haruki; Someya, Yu; Ohyama, Hirofumi; Kamei, Akihide; Morino, Isamu; Uchino, Osamu; Saito, Makoto; Noda, Hibiki; Matsunaga, Tsuneo
- Abstract
The Greenhouse gases Observing SATellite (GOSAT) was launched on January 23, 2009, intoa sun-synchronous orbit at an altitude of 666 km with 3-day revisit cycle, and has beenoperating for about ten years. GOSAT is equipped with two instruments: the Thermal AndNear-infrared Sensor for carbon Observation Fourier Transform Spectrometer (TANSO-FTS)and the Cloud and Aerosol Imager (TANSO-CAI). TANSO-FTS has three narrow bands inthe short-wavelength infrared (SWIR) region (0.75-0.78, 1.56-1.72, and 1.92-2.08 μm) and awide thermal infrared (TIR) band (5.5-14.3 μm) at a spectral sampling interval of about 0.2cm−1. The TANSO-FTS instantaneous field of view (IFOV) is 15.8 mrad, corresponding to anadir footprint diameter of 10.5 km. TANSO-CAI has four narrow bands in thenear-ultraviolet to near-infrared region at 0.38, 0.674, 0.87, and 1.6 μm with a higher spatialresolution than TANSO-FTS. TANSO-CAI can detect optically thick clouds within theTANSO-FTS IFOV. The column-averaged dry air mole fractions of carbon dioxide,methane, and water vapor (XCO2, XCH4, and XH2O; hereafter called Xgas) have beenretrieved globally from cloud-free SWIR spectral data of TANSO-FTS. Xgas aresimultaneously retrieved using a so-called full-physics retrieval method, and itsaccuracy and precision are evaluated by comparing with the Total Carbon ColumnObserving Network (TCCON) data. TCCON data is also utilized for an empirical biascorrection of Xgas. Both bias-corrected and bias-uncorrected Xgas are released as theFTS SWIR L2 product and available via GOSAT Data Archive Service (GDAS;https://data2.gosat.nies.go.jp/). As a successor mission to the GOSAT, GOSAT-2 was launched on October 29, 2018, intoa sun-synchronous orbit at an altitude of 613 km with 6-day revisit cycle. GOSAT-2 is alsoequipped with two instruments: TANSO-FTS-2 and TANSO-CAI-2. TANSO-FTS-2 has threeSWIR bands (0.75-0.77, 1.56-1.69, and 1.92-2.33 μm) and two TIR bands (5.5-8.4 and8.4-14.3 μm) at a spectral sampling interval of about 0.2 cm−1. The TANSO-FTS-2 IFOV isalso 15.8 mrad, corresponding to a nadir footprint diameter of 9.7 km. TANSO-CAI-2has five forward-looking (+20˚) bands at 0.343, 0.443, 0.674, 0.869, and 1.63μm and five backward-looking (-20˚) bands at 0.380, 0.550, 0.674, 0.869, and1.63 μm. TANSO-CAI-2 provides cloud information from forward-looking bandsand backward-looking bands, independently. The SWIR L2 retrieval algorithmfor GOSAT-2 is developing based on the latest retrieval algorithm for GOSAT.Since the spectral range of TANSO-FTS-2 is expanded to cover the 2.3 μm carbonmonoxide (CO) absorption band, XCO is also retrieved simultaneously with other gasesin the full-physics retrieval method. In addition to the full-physics based XCO2,XCH4, XH2O, and XCO products, we are planning to provide the proxy-basedXCH4 product as well as solar induced chlorophyll fluorescence (SIF) product.GOSAT-2 will start its operational observation from February 2019. We will present thepreliminary retrieval results from SWIR data of GOSAT-2 TANSO-FTS-2 in the session.
- Subjects
ATMOSPHERIC carbon dioxide; FOURIER transform spectrometers; CHLOROPHYLL spectra; GREENHOUSE gases; DATA libraries; OPTICAL hole burning
- Publication
Geophysical Research Abstracts, 2019, Vol 21, p1
- ISSN
1029-7006
- Publication type
Article