Index Geophysics

Atmospheric constraints on the methane emissions from the East Siberian Shelf

Subsea permafrost and hydrates in the East Siberian Arctic Shelf (ESAS) constitute a substantial carbon pool, and a potentially large source of methane to the atmosphere. Previous studies based on interpolated oceanographic campaigns estimated atmospheric emissions from this area at 8–17 TgCH₄ yr⁻¹. Here, we propose insights based on atmospheric observations to evaluate these estimates. The comparison of high-resolution simulations of atmospheric methane mole fractions to continuous methane observations during the whole year 2012 confirms the high variability and heterogeneity of the methane releases from ESAS. A reference scenario with ESAS emissions of 8 TgCH₄ yr⁻¹, in the lower part of previously estimated emissions, is found to largely overestimate atmospheric observations in winter, likely related to overestimated methane leakage through sea ice. In contrast, in summer, simulations are more consistent with observations. Based on a comprehensive statistical analysis of the observations and of the simulations, annual methane emissions from ESAS are estimated to range from 0.0 to 4.5 TgCH₄ yr⁻¹. Isotopic observations suggest a biogenic origin (either terrestrial or marine) of the methane in air masses originating from ESAS during late summer 2008 and 2009.

Berchet, Antoine

Bousquet, Philippe

Pison, Isabelle

Locatelli, Robin

Chevallier, Frédéric

Paris, Jean-Daniel

Dlugokencky, Ed J.

Laurila, Tuomas

Hatakka, Juha

Viisanen, Yrjo

Worthy, Doug E. J.

Nisbet, Euan

Fisher, Rebecca

France, James

Lowry, David

Ivakhov, Viktor

Hermansen, Ove

2018-09-13

Text

application/pdf

10.5194/acp-16-4147-2016

https://acp.copernicus.org/articles/16/4147/2016/

eISSN: 1680-7324

eng