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Global Land Ice Measurements from Space (GLIMS) and Satellite Image Classification and Glacier Dynamics in Alaska

Thursday, March 12, 2009
Jeffrey
Kargel (Department of Hydrology & Water Resources, UA)

GLIMS (www.glims.org) is a global remote sensing consortium now involving over 150 researchers from about 29 countries. The project is using a wide variety of satellite remote sensing data but especially has been relying on ASTER and other high resolution multispectral systems. A global glacier database has been developed and is maintained at the National Snow and Ice Data Center in Boulder, Colorado with data inputs coming from researchers around the world. Although I manage the global program, and I will briefly describe the goals, organization, and achievements of the consortium, I will primarily discuss examples of glacier image analysis in my primary field research area in Alaska. Using ASTER images, our research group has performed Fuzzy C Means classification of the multispectral data and have found that this algorithm is able to make correct classifications of snow, ice, water, rock debris, different vegetation types, and so on, when other simple ratio-based indices generally fail. Fuzzy C Means classifiers also produce quantitative (and, for the most part, accurate) assessments of subpixel mixing of different materials. Our field- and satellite-based assessments of glacier dynamics have focused especially on the roles of debris accumulation on glaciers (from seismicity induced landslides and glacial erosion), stagnation of debris-covered ice masses, vegetational succession and growth on recently deglaciated surfaces and debris-covered ice terrains, supraglacial and ice marginal lake formation and drainage, and processes of glacier damming of major rivers. Modern glacier processes in and around the Copper River Basin are similar to those during the Pleistocene, but major ice caps at that time were able to completely dam all the outlets of the Copper River Basin; one of North America's great ice-dammed glacial lakes (Glacial Lake Ahtna) formed and then drained. The processes since that time to the present era are possibly presaging what will elapse many times over as Greenland and the West Antarctic Ice Sheet progressively disintegrate in the coming centuries due to greenhouse induced global warming. Glacial Lake Ahtna also serves as a possible analog of Lake Vostok and other subglacial Antarctic lakes, and glacial lakes on ancient Mars. Other possible Mars analogs include ice capped volcanoes and hydrothermal sites, massive debris flows emanating from those volcanoes, and the region's permafrost and thermokarst.

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