2002 ARCSS All-Hands Workshop

Active Layer Thickness and Permafrost Temperature Regime (past, present and future) within the East-Siberian Transect: Modeling Approach using GIS.

Tatiana S. Sazonova¹, Vladimir E. Romanovsky², Dmitri O. Sergueev³, Gennadyi S. Tipenko^4
1Permafrost Lab, Geophysical Institute, University of Alaska Fairbanks, P.O.Box 757320 , Fairbanks, AK, 99775-7320, USA, Phone 907-474-5321, Fax 907-474-7290, ftts1@uaf.edu
²Permafrost Lab, Geophysical Institute, University of Alaska Fairbanks, P.O. Box 757320, Fairbanks, AK, 99775-7320, USA, Phone 907-474-7459, Fax 907-474-7290, ffver@uaf.edu
³Permafrost Lab, Geophysical Institute, University of Alask Fairbanks, P.O. Box 757320, Fairbanks, AK, 99775-7320, USA, Phone 907-474-5321, Fax 907-474-7290, fndos@uaf.edu
⁴Permafrost Lab, Geophysical Institute, University of Alaska Fairbanks, P.O. Box 757320, Fairbanks, AK, 99775-7320, USA, Phone 907-474-5321, Fax 907-474-7290, ffgst@uaf.edu

Understanding land-atmosphere interactions in Arctic ecosystems requires information on the potential response of the thermal regime of permafrost and the active layer to seasonal, interannual and long-term climatic variability and change. The contents of free and bounded water and temperature regime within the active layer are primary factors that quantify the magnitudes of summer and winter respiration and carbon fluxes, which are the results of microbial and other biological activities. Any changes in the active layer have a direct impact on the temperature regime and consequently on dynamics of permafrost and permafrost stability. In turn, the active layer thickness and temperature regime depend mostly on combination of climatic parameters such as mean annual air temperature and annual air temperatures amplitude, let alone the mean annual snow cover thickness, soils thermal properties, and moisture content.

Our study area encompasses the Tiksi-Yakutsk East Siberian transect, designated as the Far East Siberian transect in the IGBP Northern Eurasia Study project (IGBP-NES) (IGBP, 1996), is centered on the 135° meridian, and is a collaborative effort of IGBP-NES with the GAME project of the WCRP. The ecosystem and the permafrost within the transect are especially vulnerable to the positive changes in active layer thickness and temperature. Permafrost in East Siberia contains significant amount of ice in the form of segregated ice, ice wedges and buried layers of ice. If summer thawing will reach the ice horizon, or if the temperature in the permafrost rises, so that the process of permafrost thawing will start, then major changes in the ecosystem may occur; for example, wetlands or grasslands may gradually replace the boreal forest.

The purpose of this work is to show the spatial extent and dynamics of the active layer thickness and its influence on permafrost stability for different scenarios of climate changes, with the means of ArcView software. In order to calculate active layer thickness and permafrost temperature, we chose Kudryavtsev's equations. The major parameters in these equations are mean annual air temperature and seasonal air amplitudes. Also, mean annual snow thickness, thermophysical properties of snow and soils (heat capacity and thermal conductivity) and soil moisture are taking into account.

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