CGRG Bibliography of Canadian Geomorphology
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Author : Hachem, S.; and Allard, M.
Date : 2008.
Title : Improving permafrost distribution map by superimposing surface material maps.
Publication : International Arctic Change 2008 Conference. December 9-12, 2008. Quebec City, Quebec.
Issue : Conference Programme and Abstracts
Page(s) : 228.
Abstract
Climate change scenarios predict that global warming will be greatest over high latitudes and that permafrost areas will be among the regions most heavily affected. Data obtained from spacecrafts offer a significant advantage for studies conducted in Arctic and sub-Arctic areas where measurement stations are geographically scattered. The land surface (skin) daily global temperature 1-km (LST) products of the MODerate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra and Aqua satellite platforms were used as a mean to approach limits of permafrost zones. A model simulating the temperature time evolution has been driven to generate maps and compensate for the large number of cloudy days (more than 50% of cloudy days in every year) in Arctic regions. Hence, calculations of mean monthly and annual surface temperatures, thawing index (Ti), freezing index (Fi) for each pixel lead to the production of regional maps at a small cartographic scale, through northern Canada and Alaska. The maps follow a logical (expected) geographical distribution of surface temperatures with isotherms corresponding to known climatic, permafrost and biogeographical boundaries or transitions. Nevertheless, if the most important parameter, surface temperature that controls the ground thermal regime in permafrost is accessible via this model, it needs to be improved. The surface temperature retrieved is the “skin” temperature, in other words it is the envelope temperature above vegetation and water bodies in summer and at the surface of snow cover in winter rather than true soil surface temperature at the atmosphere/soil interface over permafrost terrain. New investigations involving the physical characteristics of surface materials (vegetation, snow, organic layers of soils, moisture content) are in process. Some sites in northern Canada are chosen for their variety in degrees of landscape heterogeneity (e.g. barren, dry/moist/wet/ tundra, open forest near tree line). This will allow us to determine how snow, vegetation, and moisture conditions can change the strength of the relationship between the satellite-based measurement (1 km2 pixel) and that recorded in the field. The project is to improve the permafrost map drawn previously by adding surface material maps – MODIS snow product, SSMI snow water equivalent product, land cover map and surficial geological map – as layers to a GIS software.
Bibliography of Canadian Geomorphology