Title: Tropical Methane Emissions: A Revised View from SCIAMACHY Onboard ENVISAT
Authors: FRANKENBERG. C.BERGAMASCHI PETERBUTZ AndreHOUWELING SanderMEIRINK Jan FokkeNOTHOLT JustusPETERSEN KatinkaSCHRIJVER HansWARNEKE ThorstenABEN Ilse
Citation: GEOPHYSICAL RESEARCH LETTERS vol. 35 p. L15811-1 L15811-5
Publisher: AMER GEOPHYSICAL UNION
Publication Year: 2008
JRC Publication N°: JRC45288
ISSN: 0094-8276
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC45288
DOI: 10.1029/2008GL034300
Type: Articles in Journals
Abstract: Methane retrievals from near-infrared spectra recorded by the SCIAMACHY instrument onboard ENVISAT hitherto suggested unexpectedly large tropical emissions. Even though recent studies confirm substantial tropical emissions, there were indications for an unresolved error in the satellite retrievals. Here we identify a retrieval error related to inaccuracies in water vapor spectroscopic parameters, causing a substantial overestimation of methane correlated with high water vapor abundances. We report on the overall implications of an update in water spectroscopy on methane retrievals with special focus on the 11 tropics where the impact is largest. The new retrievals are applied in a four-dimensional variational (4D-VAR) data assimilation system to derive a first estimate of the impact on tropical CH4 sources. Compared to inversions based on previous SCIAMACHY retrievals, annual tropical emission estimates are reduced from 267 to about 208 TgCH4 but still remain higher than previously anticipated.
JRC Institute:Institute for Environment and Sustainability

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