Parker, Robert and Boesch, Hartmut and Cogan, Austin and Fraser, Annemarie and Feng, Liang and Palmer, Paul I. and Messerschmidt, Janina and Deutscher, Nicholas and Griffith, David W. T. and Notholt, Justus and Wennberg, Paul O. and Wunch, Debra (2011) Methane observations from the Greenhouse Gases Observing SATellite: Comparison to ground‐based TCCON data and model calculations. Geophysical Research Letters, 38 . Art. No. L15807. ISSN 0094-8276 http://resolver.caltech.edu/CaltechAUTHORS:20110902-112604849
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We report new short-wave infrared (SWIR) column retrievals of atmospheric methane (X_(CH4)) from the Japanese Greenhouse Gases Observing SATellite (GOSAT) and compare observed spatial and temporal variations with correlative ground-based measurements from the Total Carbon Column Observing Network (TCCON) and with the global 3-D GEOS-Chem chemistry transport model. GOSAT X_(CH4) retrievals are compared with daily TCCON observations at six sites between April 2009 and July 2010 (Bialystok, Park Falls, Lamont, Orleans, Darwin and Wollongong). GOSAT reproduces the site-dependent seasonal cycles as observed by TCCON with correlations typically between 0.5 and 0.7 with an estimated single-sounding precision between 0.4–0.8%. We find a latitudinal-dependent difference between the X_(CH4) retrievals from GOSAT and TCCON which ranges from 17.9 ppb at the most northerly site (Bialystok) to −14.6 ppb at the site with the lowest latitude (Darwin). We estimate that the mean smoothing error difference included in the GOSAT to TCCON comparisons can account for 15.7 to 17.4 ppb for the northerly sites and for 1.1 ppb at the lowest latitude site. The GOSAT X_(CH4) retrievals agree well with the GEOS-Chem model on annual (August 2009 – July 2010) and monthly timescales, capturing over 80% of the zonal variability. Differences between model and observed X_(CH4) are found over key source regions such as Southeast Asia and central Africa which will be further investigated using a formal inverse model analysis.
|Additional Information:||© 2011 American Geophysical Union. Received 20 April 2011; accepted 27 June 2011; published 6 August 2011. We thank JAXA, NIES, and MOE for the GOSAT data and their continuous support as part of the Joint Research Agreement. R.P., L.F., and A.F. are supported by the NCEO and H.B. is supported by a RCUK fellowship. We also thank the OCO team at JPL for supplying the retrieval algorithm. We thank the BADC for providing ECMWF Operational Analyses data. TCCON is supported by NASA’s Terrestrial Ecology Program through a grant to the California Institute of Technology. Operations support for Lamont and Darwin is provided by NASA’s OCO. For the TCCON sites at Bialystok and Orleans, we thank AeroMeteo Service and the RAMCES team at LSCE for station maintenance and acknowledge the funding by the GOSAT team and within the EU‐projects IMECC and GEOmon. We would also like to thank Geoff Toon for his advice and comments. The Editor thanks two anonymous reviewers for their assistance in evaluating this paper.|
|Official Citation:||Parker, R., et al. (2011), Methane observations from the Greenhouse Gases Observing SATellite: Comparison to ground-based TCCON data and model calculations, Geophys. Res. Lett., 38, L15807, doi:10.1029/2011GL047871.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||02 Sep 2011 21:18|
|Last Modified:||26 Dec 2012 13:39|
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