Top-down versus bottom-up estimates of methane fluxes over the East Siberian Arctic Shelf

Wednesday, 17 December 2014
Natalia E Shakhova1, Igor Peter Semiletov1,2, Irina Repina3, Anatoly Salyuk4, Denis Kosmach4, Denis Chernykh5 and Artem Aniferov3, (1)University of Alaska Fairbanks, Fairbanks, AK, United States, (2)National Tomsk Research Polytech University, Russia, Tomsk, Russia, (3)Inst Atmospheric Physic, Moscow, Russia, (4)Russian Academy of Sciences, Pacific Oceanological Institute FABRAS, Vladivostok, Moscow, Russia, (5)Russian Academy of Sciences, Pacific Oceanological Institute, Moscow, Russia
Global methane (CH4) emissions are currently quantified from statistical data without testing the results against either distribution of the actual atmospheric CH4 concentrations observed in different part of the globe or the regional dynamics of these concentrations. Measurement methods despite been improved remarkably in the past few years, especially with the advent of new optical and satellite-derived methods, are limited in their applicability in the Arctic. Modeling methodologies are still under development and cannot help to evolve very coarse global-scale understanding of CH4 sources to resolution of regional-scale emissions. As a result, contribution of the Arctic sources in the global CH4 budget are yet to be quantified adequately. We used a decadal observational data set collected from the water column and from the atmospheric boundary layer (ABL) over the East Siberian Arctic Shelf (ESAS), which is the largest continental shelf, to determine the minimum source strength required to explain observed seasonally increased concentration of CH4 in the ABL. The results of top-down modeling performed by implementing a simple box model show a good agreement with results of bottom-up estimates made using interpretation of in-situ calibrated sonar data.