Methane emission bursts from permafrost environments during autumn freeze-in: New insights from ground-penetrating radar

Large amounts of methane (CH4) are known to be emitted from permafrost environments during the autumn freeze-in, but the specific soil conditions leading up to these bursts are unclear. Therefore, we used an ultrawide band ground-penetrating radar in Northeast Greenland in autumn 2009 to estimate th...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Pirk, Norbert, Santos, Telmo, Gustafson, Carl, Johansson, Anders J, Tufvesson, Fredrik, Parmentier, Frans-Jan, Mastepanov, Mikhail, Christensen, Torben
Format: Article in Journal/Newspaper
Language:English
Published: American Geophysical Union (AGU) 2015
Subjects:
Online Access:https://lup.lub.lu.se/record/7766980
https://doi.org/10.1002/2015GL065034
Description
Summary:Large amounts of methane (CH4) are known to be emitted from permafrost environments during the autumn freeze-in, but the specific soil conditions leading up to these bursts are unclear. Therefore, we used an ultrawide band ground-penetrating radar in Northeast Greenland in autumn 2009 to estimate the volumetric composition inside the soil through dielectric characterization from 200 to 3200 MHz. Our results suggest a compression of the gas reservoir during the phase transition of soil water, which is accompanied by a peak in surface CH4 emissions. About 1 week thereafter, there seems to be a decompression event, consistent with ground cracking which allows the gas reservoir to expand again. This coincides with the largest CH4 emission, exceeding the summer maximum by a factor of 4. We argue that these complementary measurement techniques are needed to come to an understanding of tundra CH4 bursts connected to soil freezing.