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Ice Thickness Data, Gulkana Glacier, Alaska

On March 28, 1976, a portable ground-based 5 MHz monopulse ice-radar system was used to measure ice thickness at 19 locations: one near measurement site D, seven along a cross profile of the glacier near measurement site B, and 11 along a cross profile of the glacier near measurement site A  The cross profile of the glacier near measurement site B was roughly located in the field by walking along a range line that extends from survey monument No through survey monument Yes and on across the glacier. A similar process was executed for the cross profile near measurement site A except that in this case the reference survey monuments, There and M, are located on opposite sides of the glacier. See March (2000) for more detail about this data.


Location of ice radar midpoints and survey monuments M, There, No, and Yes in Gulkana Glacier Basin. No, which is difficult to distinguish from Yes at the scale of this map, lies about 23 m to the northwest of Yes. (Map coordinates are UTM, zone 6; datum is NAD1983.)


JPG image of ice radar data table (62 Kbytes), click image to link to ASCII version of table.

From our measurements of the glacier surface altitude at sites A, B, and D, we know that the glacier ice thickness undergoes both seasonal variation and longer term variations as the glacier adjusts itself to changes in climate. If we assume that the glacier bed has not eroded significantly between 1976 and 1995, then the surface lowering indicates that the cumulative glacier thinning from March 1976 (the date of our radar measurements) to March 1995 along the glacier centerline is about 23 m at site A and 7 m at site B with no cumulative change at site D. The seasonal variation in glacier surface altitude indicates that the ice thickness varies over the whole glacier by about 2-5 m from a peak thickness in May or June to a minimum in August or September.  (Click here for ASCII version of data table.)
 


Maintainer: Rod March
Last update: Monday, December 27, 2010 05:06 PM
URL: http://ak.water.usgs.gov/glaciology/gulkana/ice_thickness/index.htm