Variability of methane fluxes over high latitude permafrost wetlands

Atmospheric methane plays an important role in the global climate system. Due to significant amounts of organic
\nmaterial stored in the upper layers of high latitude permafrost wetlands and a strong Arctic warming trend,
\nthere is concern about potentially large methane emissions from Arctic and sub-Arctic areas. The quantification
\nof methane fluxes and their variability from these regions therefore plays an important role in understanding
\nthe Arctic carbon cycle and changes in atmospheric methane concentrations. However, direct measurements of
\nmethane fluxes in permafrost regions are sparse, very localized, inhomogeneously distributed in space, and thus
\ndifficult to use for accurate model representation of regional to global methane contributions from the Arctic.
\nWe aim to contribute to reducing uncertainty and improve spatial coverage and spatial representativeness
\nof flux estimates by using airborne eddy covariance measurements across large areas. The research aircraft
\nPOLAR 5 was equipped with a turbulence nose boom and a fast response methane analyzer and served as the
\nplatform for measurements of methane emissions. The measuring campaign was carried out from 28 June to 10
\nJuly 2012 across the entire North Slope of Alaska and the Mackenzie Delta in Canada.
\nThe supplemented simulations from the Weather Research and Forecasting (WRF) model exploring the dynamics
\nof the atmospheric boundary layer were used to analyze high methane concentrations occasionally
\nobserved within the boundary layer with a distinct drop to background level above. Strong regional differences
\nwere detected over both investigated areas showing the non-uniform distribution of methane sources. In order to
\ncover the whole turbulent spectrum and at the same time to resolve methane fluxes on a regional scale, different
\nintegration paths were analyzed and validated through spectral analysis. Methane emissions measured over the
\nMackenzie Delta were higher and generally more variable in space, especially in the outer Delta with known
\ngeogenic methane seepage. On the North Slope, methane fluxes were larger in the western part than in the central
\nand eastern parts.
\nThe obtained results are essential for the advanced, scale dependent quantification of methane emissions.
\nOur contribution will present an overview of the experiment as well as preliminary results from more than 52
\nflight hours over high latitude permafrost wetlands.

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