CGRG Bibliography of Canadian Geomorphology
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Author : Goulden, T.; Hopkinson, C.; and Demuth, M.
Date : 2010.
Title : Sensitivity of glacial change detection to datum transformations.
Publication : CMOS-CGU Ottawa 2010. 44th Annual CMOS Congress, 36th Annual Scientific Meeting of CGU, 3rd Joint CMOS-CGU Congress. May 31-June 4, 2010. Ottawa, Ontario.
Issue :
Page(s) :
Abstract
Physical changes in our environment characterize shifts in global patterns and are indications of climate change. Alpine glaciers are highly sensitive to variations long term climatic variations. To chronicle the activity of alpine glaciers an analysis of legacy data and comparison with modern observations is necessary. The historical record of alpine glaciers often consists of paper topographic maps produced in out-dated geographic datums. For appropriate change detection it is essential all data be spatially coincident requiring historical observations be transformed to a modern datum. Failure to execute this will lead to incorrect conclusions about the glacial system and subsequently false implications of climate change. In Canada, horizontal reference of historical map products was the North American Datum of 1927 (NAD27) and current map products is the North American Datum of 1983 Canadian Spatial Reference System (NAD83 CSRS). An analysis of the sensitivity of three glacial sites in Western Canada was completed to determine the effects of ignoring datum transformations in the change detection process. This was performed by purposefully comparing historical glacial surface observations in NAD27 with current observations in NAD83 CSRS. Consideration was also given to the sensitivity of derived change to vertical reference systems. This focussed on the ability of current satellite positioning technology to produce elevations directly to the surface of the reference ellipsoid while historical data is traditionally referenced to mean sea level. From the sensitivity analysis key distinguishing characteristics of these errors were identified to quickly ascertain whether observed changes are the result of a physical trend in the environment or negligence in reconciling spatial reference.
Bibliography of Canadian Geomorphology