#2009 SPECTRA SERIES#

In order to reduce the influence of temporal and spatial heterogeneity of each gas concentration on the evaluation results, data satisfying the following match-up conditions are selected for comparisons in (1) and (2). (3) Comparison of monthly mean concentrations in the 10° latitude x 10° longitude area for GOSAT and GOSAT-2 (2) Comparison of GOSAT and GOSAT-2 synchronous observation data (1) Comparison of TCCON data with each satellite data Since those for GOSAT-2 have not been released, bias correction using the multiple regression analysis is applied to GOSAT-2 data in this study.įor bias-corrected CO 2 and CH 4 concentration data, the following analyses are conducted. During the validation activities, empirical bias correction methods using multiple regression analysis (an analytical technique that derives a relational equation to explain one data set with two or more other data sets) have been developed and evaluated, and bias-corrected Level 2 products for GOSAT have been released. However, there are always some differences between the information used in the analysis and reality, causing errors in the concentration data. The greenhouse gas concentration retrieval algorithm developed by NIES is designed to improve the retrieval accuracy and precision by taking into account the effects of aerosols scattering and changes in instrument characteristics that can cause errors in the retrieved concentrations (*4).

#2009 SPECTRA SERIES#

In this study, we compared CO 2 and CH 4 concentration data obtained from the two GOSAT series satellites to investigate the extent to which systematic differences in the concentration data between satellites vary temporally and/or spatially. In developing long-term concentration data sets by GOSAT series, it is important to ensure the inter-satellite data consistency. The validation and quality evaluation of the retrieved concentration data have been conducted for each satellite using data from the ground-based Fourier transform spectrometer observation network TCCON (*3), but comparison of the concentration data among satellites has not been conducted so far. The column-averaged dry air mole fractions (*1) of carbon dioxide (CO 2) and methane (CH 4) have been retrieved from the Short-Wavelength InfraRed (SWIR) spectra (*2) observed by these sensors, and the retrieval results are released as Level 2 products by NIES. GOSAT and GOSAT-2 are equipped with the greenhouse gas observation sensors the Thermal And Near-infrared Sensor for carbon Observation – Fourier Transform Spectrometer (TANSO-FTS) and TANSO-FTS-2, respectively. NIES is responsible for developing and improving the retrieval algorithms of greenhouse gas concentrations for data observed by the GOSAT series, and validation and quality evaluation of the retrieval results. The Ministry of the Environment of Japan, the National Institute for Environmental Studies (NIES), and the Japan Aerospace Exploration Agency are jointly promoting the GOSAT series, a series of Earth observation satellites whose main purpose is to observe greenhouse gases from space the Greenhouse gases Observing SATellite (GOSAT) launched in January 2009 and GOSAT-2 launched in October 2018 are currently in operation, and the Global Observing SATellite for Greenhouse gases and Water cycle (GOSAT-GW) is planned to be launched in Japan's FY2024. National Institute for Environmental Studies

2009 spectra