Jan. 21th ESS Seminar: Permafrost mapping and modelling in the Nordic area in a period of climate change

Date: 2013年1月21日（月） 5:30pm〜7pm

Venue: Room D201

Title:
(1) Permafrost mapping and modelling in the Nordic area in a period of climate change
(Bernd Etzelmueller, Department of Geosciences, University of Oslo, Norway)
(2) Topic related to permafrost and remote sensing (To be determined)
(Sebastian Westermann, Department of Geosciences, University of Oslo, Norway)

Chair: 石川　守　准教授（統合環境科学部門）

Abstract: Permafrost covers around 22% of the earth’s land mass in the Northern Hemisphere and is defined purely thermally. Because of the thermal definition, the permafrost distribution in the world is governed by the energy exchange processes at the atmosphere-land surface boundary, and thus mainly regulated by climate conditions in a global scale. In regional and local scale topography, snow, vegetation and sediment properties modulate these energy exchange processes and thus ground temperatures. Permafrost is therefore abundant where the mean annual ground surface temperature (MAGST) remains below 0℃, which is the case in a zone around the poles outside the glacier ice cover. This zonal Arctic and Antarctic permafrost area is often but not always spatially separated from alpine or mountain permafrost, which is restricted to the higher elevations in most mountain chains in the world including the Tibetan Plateau. Permafrost is important for understanding geomorphological processes and thus landform and landscape development, sediment budgets and engineering stability problems for construction and hazard mitigation. This is related to the existence of water in the ground, and the phase changes and associated volume changes happening during freezing and thawing. These processes highly govern the thermal properties of the ground, and its mechanical behaviour. As permafrost is thermally defined and ultimately depends on the surface energy balance it is also a climate indicator. Ground temperatures in greater depths represent former climate conditions under the absence of advective heat transport. Furthermore, permafrost encapsulates climate gasses in the ground and prevents biological decomposition of organic material.
The lecture summarises and discuss permafrost distribution, modelling and thermal and mechanical behaviour of permafrost in a changing climate, with special emphasis on the mountain regions of the Nordic area.

※今回の研究院アワーは普段みなさんにとってあまり馴染みがない永久凍土を取り上げます。見えない永久凍土の分布はどのように調べられるのか。リモートセンシングや地理情報システム(GIS)などを駆使した方法についてヨーロッパ山岳永久凍土を事例に、この分野の世界的な第一人者にわかりやすく説明していただきます。