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Mass
Balance, Meteorology, Area Altitude Distribution, Glacier-Surface Altitude,
Ice Motion, Terminus Position, and Runoff at Gulkana Glacier, Alaska, 1996
Balance Year
by Rod S. March
U.S. GEOLOGICAL SURVEY
Water-Resources Investigations Report 03-4095
ABSTRACT
The 1996 measured winter snow, maximum winter snow, net, and annual
balances in the Gulkana Glacier Basin were evaluated on the basis of
meteorological, hydrological, and glaciological data. Averaged over the
glacier, the measured winter snow balance was 0.87 meter on April 18, 1996,
1.1 standard deviation below the long-term average; the maximum winter snow
balance, 1.06 meters, was reached on May 28, 1996; and the net balance (from
August 30, 1995, to August 24, 1996) was -0.53 meter, 0.53 standard
deviation below the long-term average. The annual balance (October 1, 1995,
to September 30, 1996) was -0.37 meter. Area-averaged balances were reported
using both the 1967 and 1993 area altitude distributions (the numbers
previously given in this abstract use the 1993 area altitude distribution).
Net balance was about 25 percent less negative using the 1993 area altitude
distribution than the 1967 distribution.
Annual average air temperature was 0.9 degree Celsius warmer than that
recorded with the analog sensor used since 1966. Total precipitation catch
for the year was 0.78 meter, 0.8 standard deviations below normal. The
annual average wind speed was 3.5 meters per second in the first year of
measuring wind speed. Annual runoff averaged 1.50 meters over the basin, 1.0
standard deviation below the long-term average.
Glacier-surface altitude and ice-motion changes measured at three index
sites document seasonal ice-speed and glacier-thickness changes. Both showed
a continuation of a slowing and thinning trend present in the 1990s.
The glacier terminus and lower ablation area were defined for 1996 with a
handheld Global Positioning System survey of 126 locations spread out over
about 4 kilometers on the lower glacier margin. From 1949 to 1996, the
terminus retreated about 1,650 meters for an average retreat rate of 35
meters per year.
March, R.S., 2003, Mass Balance, Meteorology, Area Altitude Distribution,
Glacier-Surface Altitude, Ice Motion, Terminus Position, and Runoff at
Gulkana Glacier, Alaska, 1996 Balance Year: U.S. Geological Survey
Water-Resources Investigations Report 03-4095, 33 p.
[Full Report, Acrobat PDF (2.6 MB)]
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Maintainer: Rod March
Last update:
Tuesday, June 27, 2006 04:26 PM
URL: http://ak.water.usgs.gov/glaciology/gulkana/reports/wrir03-4095/
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