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Global column‐averaged methane mixing ratios from 2003 to 2009 as derived from SCIAMACHY: Trends and variability

Frankenberg, C. and Aben, I. and Bergamaschi, P. and Dlugokencky, E. J. and van Hees, R. and Houweling, S. and Van der Meer, P. and Snel, R. and Tol, P. (2011) Global column‐averaged methane mixing ratios from 2003 to 2009 as derived from SCIAMACHY: Trends and variability. Journal of Geophysical Research D, 116 (D4). Art. No. 04302. ISSN 0148-0227.

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After a decade of stable or slightly decreasing global methane concentrations, ground-based in situ data show that CH_4 began increasing again in 2007 and that this increase continued through 2009. So far, space-based retrievals sensitive to the lower troposphere in the time period under consideration have not been available. Here we report a long-term data set of column-averaged methane mixing ratios retrieved from spectra of the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) instrument onboard Envisat. The retrieval quality after 2005 was severely affected by degrading detector pixels within the methane 2ν_3 absorption band. We identified the most crucial problems in SCIAMACHY detector degradation and overcame the problem by applying a strict pixel mask as well as a new dark current characterization. Even though retrieval precision after the end of 2005 is invariably degraded, consistent methane retrievals from 2003 through 2009 are now possible. Regional time series in the Sahara, Australia, tropical Africa, South America, and Asia show the methane increase in 2007–2009, but we cannot yet draw a firm conclusion concerning the origin of the increase. Tropical Africa even seems to exhibit a negative anomaly in 2006, but an impact from changes in SCIAMACHY detector degradation cannot be excluded yet. Over Assakrem, Algeria, we observed strong similarities between SCIAMACHY measurements and ground-based data in deseasonalized time series. We further show long-term SCIAMACHY xCH_4 averages at high spatial resolution that provide further insight into methane variations on regional scales. The Red Basin in China exhibits, on average, the highest methane abundance worldwide, while other localized features such as the Sudd wetlands in southern Sudan can also be identified in SCIAMACHY xCH_4 averages.

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Frankenberg, C.0000-0002-0546-5857
Additional Information:© 2011 American Geophysical Union. Received 30 July 2010; revised 19 November 2010; accepted 30 November 2010; published 17 February 2011. CF was mostly supported by the Dutch Science Foundation (NWO) through a VENI grant. We acknowledge John Burrows, PI of the SCIAMACHY instrument, for having initiated and realized the SCIAMACHY project. The Netherlands SCIAMACHY Data Center and ESA are greatly appreciated for providing data. We thank Wouter Peters for providing CarbonTracker results and A. Segers, C. Schrijvers, O. Tuinder, and A. Gloudemans for providing ECMWF data collocated with SCIAMACHY. We acknowledge the European Commission for supporting the Sixth Framework Programme project HYMN (contract 037048) and GEOMON (contract 036677), GEMS‐IP (contract SIP4‐CT‐2004‐516099). We further acknowledge exchange of information within the EU 6th FP Network of Excellence ACCENT. The research leading to these results has received funding from the European Union’s Seventh Framework Programme (FP7/2007–2013) under Grant Agreement 218793. Part of the research was funded through the EU’s Seventh Framework Programme (FP7/2007–2013) under Grant Agreement 218793 (MACC). We further acknowledge the source of EDGAR data: European Commission, Joint Research Centre (JRC)/Netherlands Environmental Assessment Agency (PBL); Emission Database for Global Atmospheric Research (EDGAR), release version 4.0 (, 2009. We thank and honor Annemieke Gloudemans, who provided ancillary data and continued the work started in this paper. Her unexpected death is a tragic loss to all of us.
Funding AgencyGrant Number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
European Research Council (ERC)037048
European Research Council (ERC)036677
European Research Council (ERC)SIP4‐CT‐2004‐516099
European Research Council (ERC)218793
Issue or Number:D4
Record Number:CaltechAUTHORS:20150511-102738215
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Official Citation:Frankenberg, C., I. Aben, P. Bergamaschi, E. J. Dlugokencky, R. van Hees, S. Houweling, P. van der Meer, R. Snel, and P. Tol (2011), Global column‐averaged methane mixing ratios from 2003 to 2009 as derived from SCIAMACHY: Trends and variability, J. Geophys. Res., 116, D04302, doi:10.1029/2010JD014849.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:57408
Deposited By: Ruth Sustaita
Deposited On:11 May 2015 17:57
Last Modified:03 Oct 2019 08:24

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