Portland State University. Department of Geography
Andrew G. Fountain
Date of Award
Master of Science (M.S.) in Geography
1 online resource (vii, 100 pages)
The McMurdo Dry Valleys (MDV), the largest ice-free region (4,500 km2) in Antarctica, are a polar desert with an average annual temperature of -18ºC. In Taylor Valley, one of the MDV, closed-basin, perennially ice-covered lakes occupy the valley floor. Their water balance is controlled by inflow from glacial meltwater runoff and loss due to sublimation, making them sensitive indicators of climate. In this study, a physically-based model of glacier meltwater and lake ice sublimation is adapted to explain modern (1996 to 2013) lake-level variations. Meltwater model results were improved by the inclusion of MODIS remotely-sensed albedo measurements (E = 0.47; nRMSE = 0.73). After 2008 the meltwater model significantly under-predicted streamflow and only through decreasing albedo by -30% (equivalent to a decrease of -0.18 on average) did the results match observations (E = 0.79; nRMSE = 0.45). This study provides the first estimate of direct (unmeasured) glacier inflow to the lakes, 69%, 73% and 28%, and sublimation loss rates, 0.37 m yr-1, 0.24 m yr-1 and 0.16 m yr-1, for lakes Bonney, Hoare and Fryxell, respectively. Despite similar meltwater volumes entering lakes Bonney and Fryxell, the difference in basin hypsometry results in a much faster lake rise at Bonney from 2002-13.If future climate conditions match current (1996-2013) conditions, all lakes will rise through the end of the century.
Cross, Julian Michael, "Glacial Meltwater Modeling to Simulate Lake Water Budget (1996-2013) in Taylor Valley, Antarctica" (2020). Dissertations and Theses. Paper 5364.