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Published June 7, 2013 | Supplemental Material + Published
Journal Article Open

Improvement of the retrieval algorithm for GOSAT SWIR XCO_2 and XCH_4 and their validation using TCCON data

Abstract

The column-averaged dry-air mole fractions of carbon dioxide and methane (XCO_2 and XCH_4) have been retrieved from Greenhouse gases Observing SATellite (GOSAT) Short-Wavelength InfraRed (SWIR) observations and released as a SWIR L2 product from the National Institute for Environmental Studies (NIES). XCO_2 and XCH_4 retrieved using the version 01.xx retrieval algorithm showed large negative biases and standard deviations (−8.85 and 4.75 ppm for XCO_2 and −20.4 and 18.9 ppb for XCH_4, respectively) compared with data of the Total Carbon Column Observing Network (TCCON). Multiple reasons for these error characteristics (e.g., solar irradiance database, handling of aerosol scattering) are identified and corrected in a revised version of the retrieval algorithm (version 02.xx). The improved retrieval algorithm shows much smaller biases and standard deviations (−1.48 and 2.09 ppm for XCO_2 and −5.9 and 12.6 ppb for XCH_4, respectively) than the version 01.xx. Also, the number of post-screened measurements is increased, especially at northern mid- and high-latitudinal areas.

Additional Information

© 2013 Author(s). This work is distributed under the Creative Commons Attribution 3.0 License. Published by Copernicus Publications on behalf of the European Geosciences Union. Received: 19 December 2012 – Published in Atmos. Meas. Tech. Discuss.: 30 January 2013. Revised: 23 April 2013 – Accepted: 3 May 2013 – Published: 7 June 2013. The authors wish to thank Hiroshi Suto for providing useful comments on the non-linearity response of TANSO-FTS L1B and the non-linearity-corrected spectral data over ocean used in the sensitivity tests. The authors also wish to thank Ha Tran for kindly providing the line mixing and collision induced absorption code used in this study. Retrieval sensitivity tests were conducted on the GOSAT Research Computation Facility. The extended GPV dataset was provided to the GOSAT project by JMA. This research was supported in part by the Environment Research and Technology Development Fund (A-1102) of the Ministry of the Environment, Japan. US funding for TCCON comes from NASA's Terrestrial Ecology Program, grant number NNX11AG01G, the Orbiting Carbon Observatory Program, the Atmospheric C_O2 Observations from Space (ACOS) Program and the DOE/ARM Program. Information about all TCCON sites and their sources of funding can be found on the TCCON website (https://tccon-wiki.caltech.edu/). Edited by: P. Stammes.

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Published - amt-6-1533-2013.pdf

Supplemental Material - amt-6-1533-2013-supplement.pdf

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August 22, 2023
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