Methane emissions from Alaska in 2012 from CARVE airborne observations.
We determined methane (CH4) emissions from Alaska using airborne measurements from the Carbon Arctic Reservoirs Vulnerability Experiment (CARVE). Atmospheric sampling was conducted between May and September 2012 and analyzed using a customized version of the polar weather research and forecast model linked to a Lagrangian particle dispersion model (stochastic time-inverted Lagrangian transport model). We estimated growing season CH4 fluxes of 8 ± 2 mg CH4⋅m(-2)⋅d(-1) averaged over all of Alaska, corresponding to fluxes from wetlands of 56(-13)(+22) mg CH4⋅m(-2)⋅d(-1) if we assumed that wetlands are the only source from the land surface (all uncertainties are 95% confidence intervals from a bootstrapping analysis). Fluxes roughly doubled from May to July, then decreased gradually in August and September. Integrated emissions totaled 2.1 ± 0.5 Tg CH4 for Alaska from May to September 2012, close to the average (2.3; a range of 0.7 to 6 Tg CH4) predicted by various land surface models and inversion analyses for the growing season. Methane emissions from boreal Alaska were larger than from the North Slope; the monthly regional flux estimates showed no evidence of enhanced emissions during early spring or late fall, although these bursts may be more localized in time and space than can be detected by our analysis. These results provide an important baseline to which future studies can be compared.
School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138; rachel.chang@dal.ca.
Rachel Y-W
RY
Chang
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109;
Charles E
CE
Miller
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109;
Steven J
SJ
Dinardo
Global Monitoring Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, CO 80305; Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309; and.
Anna
A
Karion
Global Monitoring Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, CO 80305; Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309; and.
Colm
C
Sweeney
School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138;
Bruce C
BC
Daube
Atmospheric and Environmental Research, Inc., Lexington, MA 02421.
John M
JM
Henderson
Atmospheric and Environmental Research, Inc., Lexington, MA 02421.
Marikate E
ME
Mountain
Atmospheric and Environmental Research, Inc., Lexington, MA 02421.
Janusz
J
Eluszkiewicz
Global Monitoring Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, CO 80305; Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309; and.
John B
JB
Miller
Global Monitoring Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, CO 80305;
Lori M P
LM
Bruhwiler
School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138;
Steven C
SC
Wofsy
Alaska; Arctic; boreal; methane; tundra