GOSAT-GW TANSO-3レベル2プロダクトの検証計画

抄録

The Global Observing SATellite for Greenhouse gases and Water cycle (GOSAT-GW) will be launched in the Japanese fiscal year 2024. The Total Anthropogenic and Natural emissions mapping SpectrOmeter-3 (TANSO-3), one of the instruments onboard GOSAT-GW, is an imaging grating spectrometer that measures backscattered sunlight, from which the column-averaged dry-air mole fractions of carbon dioxide (XCO₂) and methane (XCH₄) and the total and tropospheric vertical column densities (VCDs) of nitrogen dioxide (NO₂) will be derived (TANSO-3 Level 2 products). TANSO-3 will have two observation modes: Wide Mode, with a ~900 km swath width and a ~10 km footprint size; and Focus Mode, with ~90 km × 90 km observation areas and a < 3 km footprint size. The TANSO-3 Level 2 products will be validated primarily with data from global ground-based remote sensing networks. Total Carbon Column Observing Network (TCCON) and COllaborative Carbon Column Observing Network (COCCON) data will be used to validate XCO₂ and XCH₄, while Pandonia Global Network (PGN) and Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) data will be used for NO₂ VCD. Airborne in situ measurements, satellite measurements other than GOSAT-GW, and simulated concentration fields from atmospheric transport models will complement the ground-based data. In order to validate the Focus Mode data in urban areas, it is crucial to evaluate small-scale spatial gradients in XCO₂, XCH₄, and NO₂ VCD. Therefore, we are developing an urban operational observation network in the Tokyo metropolitan area, Japan, by deploying co-located EM27/SUN (COCCON instruments) and Pandora (PGN instruments) spectrometers.