title: Enhanced methane emissions from tropical wetlands during the 2011 La Niña.
abstract: Year-to-year variations in the atmospheric methane (CH4) growth rate show significant correlation with climatic drivers. The second half of 2010 and the first half of 2011 experienced the strongest La Niña since the early 1980s, when global surface networks started monitoring atmospheric CH4mole fractions. We use these surface measurements, retrievals of column-averaged CH4mole fractions from GOSAT, new wetland inundation estimates, and atmospheric δ13C-CH4measurements to estimate the impact of this strong La Niña on the global atmospheric CH4budget. By performing atmospheric inversions, we find evidence of an increase in tropical CH4emissions of ∼6-9 TgCH4yr-1during this event. Stable isotope data suggest that biogenic sources are the cause of this emission increase. We find a simultaneous expansion of wetland area, driven by the excess precipitation over the Tropical continents during the La Niña. Two process-based wetland models predict increases in wetland area consistent with observationally-constrained values, but substantially smaller per-area CH4emissions, highlighting the need for improvements in such models. Overall, tropical wetland emissions during the strong La Niña were at least by 5% larger than the long-term mean.
authors.affiliation: Institute of Marine and Atmospheric Research Utrecht (IMAU), Utrecht, The Netherlands.|SRON Netherlands institute for Space Research, Utrecht, The Netherlands.
authors.forename: Sudhanshu
authors.initials: S
authors.lastname: Pandey
authors.affiliation: Institute of Marine and Atmospheric Research Utrecht (IMAU), Utrecht, The Netherlands.|SRON Netherlands institute for Space Research, Utrecht, The Netherlands.
authors.forename: Sander
authors.initials: S
authors.lastname: Houweling
authors.affiliation: Institute of Marine and Atmospheric Research Utrecht (IMAU), Utrecht, The Netherlands.|SRON Netherlands institute for Space Research, Utrecht, The Netherlands.|Department of Meteorology and Air Quality (MAQ), Wageningen University and Research Centre, WageningenThe Netherlands.
authors.forename: Maarten
authors.initials: M
authors.lastname: Krol
authors.affiliation: SRON Netherlands institute for Space Research, Utrecht, The Netherlands.
authors.forename: Ilse
authors.initials: I
authors.lastname: Aben
authors.affiliation: Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Monteil
authors.affiliation: SRON Netherlands institute for Space Research, Utrecht, The Netherlands.
authors.forename: Narcisa
authors.initials: N
authors.lastname: Nechita-Banda
authors.affiliation: NOAA Earth System Research Laboratory, Boulder, Colorado, USA.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Dlugokencky
authors.affiliation: SRON Netherlands institute for Space Research, Utrecht, The Netherlands.
authors.forename: Rob
authors.initials: R
authors.lastname: Detmers
authors.affiliation: SRON Netherlands institute for Space Research, Utrecht, The Netherlands.
authors.forename: Otto
authors.initials: O
authors.lastname: Hasekamp
authors.affiliation: Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA.|CAS Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Beijing, China.
authors.forename: Xiyan
authors.initials: X
authors.lastname: Xu
authors.affiliation: Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Riley
authors.affiliation: Institute on Ecosystems and Department of Ecology, Montana State University, Bozeman, USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Poulter
authors.affiliation: Swiss Federal Research Institute WSL, Birmensdorf, Switzerland.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: City College of New York, City University of New York, New York, NY, USA.
authors.forename: Kyle C
authors.initials: KC
authors.lastname: McDonald
authors.affiliation: Institute of Arctic and Alpine Research, Boulder, CO, USA.
authors.forename: James W C
authors.initials: JW
authors.lastname: White
authors.affiliation: Laboratoire des Sciences du Climatet de l'Environnement (LSCE), Gif-sur-Yvette, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Bousquet
authors.affiliation: Institute of Marine and Atmospheric Research Utrecht (IMAU), Utrecht, The Netherlands.
authors.forename: Thomas
authors.initials: T
authors.lastname: Röckmann