Seminar series nr 174

• Main Author: Norbert Pirk
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2009
• Subjects: Methane Emission Peaks from Permafrost Environments; Using Ultra–Wideband Spectroscopy; Sub-Surface Pressure Sensing and Finite Element Solving as Means of their Exploration; Greenland; permafrost
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.470.7769; http://www.natgeo.lu.se/ex-jobb/exj_174.pdf

Methane is an effective greenhouse gas of vital importance to global climate. Methane emissions from permafrost dominated peatlands contribute significantly to the dynamics of the high-latitude atmospheric methane concentration. During the freezing period of autumn 2007 a large methane emission peak was recorded at a peatland in northeast Greenland. The integral of this abrupt peak was equivalent to the emissions of the entire summer season. The present work seeks to explain this unexpected methane burst. A soil-vegetation-atmosphere transfer (SVAT) model based upon the finite element method is applied to simulate the methane emission driven by air temperature data from Greenland 2007. Laboratory experiments are developed in which the methane emissions from peat samples are monitored as they freeze. In order to relate the potential methane burst to the pressure build-up at freezing, sub-surface pressure sensors are employed. On another sample ultra-wideband microwave measurements are performed to capture gas dynamics inside the sample in a non-invasive manner. It is found that a methane emission peak at the onset of freezing is not comprised in the SVAT model. Despite a significant pressure build-up, the methane discharge at the onset of freezing does not appear in