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Methane retrievals from Greenhouse Gases Observing Satellite (GOSAT) shortwave infrared measurements: Performance comparison of proxy and physics retrieval algorithms

Schepers, D. and Guerlet, S. and Butz, A. and Landgraf, J. and Frankenberg, C. and Hasekamp, O. and Blavier, J. F. and Deutscher, N. M. and Griffith, D. W. T. and Hase, F. and Kyro, E. and Morino, I. and Sherlock, V. and Sussmann, R. and Aben, I. (2012) Methane retrievals from Greenhouse Gases Observing Satellite (GOSAT) shortwave infrared measurements: Performance comparison of proxy and physics retrieval algorithms. Journal of Geophysical Research. Atmospheres, 117 (D10). Art. No. D10307. ISSN 2169-897X. https://resolver.caltech.edu/CaltechAUTHORS:20150512-093655587

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Abstract

We compare two conceptually different methods for determining methane column-averaged mixing ratios image from Greenhouse Gases Observing Satellite (GOSAT) shortwave infrared (SWIR) measurements. These methods account differently for light scattering by aerosol and cirrus. The proxy method retrieves a CO_2 column which, in conjunction with prior knowledge on CO_2 acts as a proxy for scattering effects. The physics-based method accounts for scattering by retrieving three effective parameters of a scattering layer. Both retrievals are validated on a 19-month data set using ground-based X_CH_4 at 12 stations of the Total Carbon Column Observing Network (TCCON), showing comparable performance: for the proxy retrieval we find station-dependent retrieval biases from −0.312% to 0.421% of X_CH_4 a standard deviation of 0.22% and a typical precision of 17 ppb. The physics method shows biases between −0.836% and −0.081% with a standard deviation of 0.24% and a precision similar to the proxy method. Complementing this validation we compared both retrievals with simulated methane fields from a global chemistry-transport model. This identified shortcomings of both retrievals causing biases of up to 1ings and provide a satisfying validation of any methane retrieval from space-borne SWIR measurements, in our opinion it is essential to further expand the network of TCCON stations.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1029/2012JD017549DOIArticle
http://onlinelibrary.wiley.com/doi/10.1029/2012JD017549/abstractPublisherArticle
ORCID:
AuthorORCID
Frankenberg, C.0000-0002-0546-5857
Additional Information:© 2012 American Geophysical Union. Received 1 February 2012; revised 12 April 2012; accepted 15 April 2012; published 30 May 2012. A.B. is supported by Deutsche Forschungsgemeinschaft (DFG) through the Emmy-Noether programme, grant BU2599/1–1 (RemoteC). Access to GOSAT data was granted through the 2nd GOSAT research announcement jointly issued by JAXA, NIES, and MOE. TCCON data were obtained from the TCCON Data Archive, operated by the California Institute of Technology from the Web site at http://tccon.ipac.caltech.edu/. GTOPO30 is available from the U.S. Geological Survey through the Earth Resources Observation and Science (EROS) Center (http://eros.usgs.gov/#/Find_Data/Products_and_ Data_Available/GTOPO30_info). MODIS Atmosphere data are distributed through http://ladsweb.nascom.nasa.gov/data/search.html. CarbonTracker results are provided by NOAA-ESRL, Boulder, Colorado, USA through http://www.esrl.noaa.gov/gmd/ccgg/carbontracker/.
Funders:
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)BU2599/1–1
Issue or Number:D10
Record Number:CaltechAUTHORS:20150512-093655587
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150512-093655587
Official Citation:Schepers, D., et al. (2012), Methane retrievals from Greenhouse Gases Observing Satellite (GOSAT) shortwave infrared measurements: Performance comparison of proxy and physics retrieval algorithms, J. Geophys. Res., 117, D10307, doi:10.1029/2012JD017549.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:57442
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:12 May 2015 21:37
Last Modified:03 Oct 2019 08:24

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