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2003 Seattle Annual Meeting (November 2–5, 2003)

Paper No. 7
Presentation Time: 3:15 PM

MELTWATER PRODUCTION IN CHANNELS ON TAYLOR GLACIER, ANTARCTICA


JOHNSTON, Robin R.1, FOUNTAIN, Andrew G.2 and NYLEN, Thomas H.1, (1)Department of Geology, Portland State Univ, Room 17 Cramer Hall, 1721 SW Broadway, Portland, OR 97207-0751, (2)Department of Geology, Portand State Univ, 17 Cramer Hall, 1721 SW Broadway, Portland, OR 97207-0751, robj@pdx.edu

Deeply incised channels on Taylor Glacier in the McMurdo Dry Valleys, Antarctica provided refuge from severe weather by participants of Captain Robert Scott’s expeditions early in the last century. The channels initiate from medial moraines and start out only several cm deep and 10’s of cm wide, but at the glacier terminus they reach 120 m wide and 30 m deep. Channel initiation is triggered by the lower albedo of morainal material compared to the surrounding ice. Once formed, the climate within the channel differs from that of the glacier surface. In the channels, average air temperature is warmer by 1.5°C and wind speed is reduced by roughly 2.4 ms-1.

Previous research shows that ablation on the glacier surface is dominated by sublimation (60-80%), with melt making up the balance. Energy balance calculations, based on measurements within the channels, show that melt constitutes 99% of the ablation within the channels and the balance is taken up by sublimation. This is due primarily to lower wind speed in the channels compared to the glacier surface and more intense solar radiation due to the angle of the channel walls. Ablation in the channels for the 2000-01 season was roughly 3 times the measured ablation at the glacier surface.

An important result from the difference in microclimates and energy balances within the channels compared to the glacier surface, for the same overall climatic conditions, is that melting occurs in the channels while the glacier surface remains below freezing. Taylor’s party found this out in 1911 when their tent, located in the channel, flooded with water. The channels therefore not only convey melt water, but they are also the primary producers of melt water. Over the 1995-97 period, the channels were estimated to produce 3.05x105 m3 of water. This is close to the value of 4.30x105 m3, which represents the difference in volume from lake level rise and known stream contributions, and represents 28% of the total volume increase for Lake Bonney.

Session No. 179

T111. McMurdo Dry Valleys, Antarctica, 1903–2003: A Celebration of a Century of Science
Tuesday, 4 November 2003: 1:30 PM-5:30 PM
Geological Society of America Abstracts with Programs. Vol. 35, No. 6, September 2003, p.464
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