@mastersthesis {4451, title = {Glacial meltwater modeling to simulate lake water budget (1996-2013) in Taylor Valley, Antarctica}, volume = {M.S.}, year = {2020}, month = {01/2020}, school = {Portland State University}, type = {masters}, address = {Portland, OR}, abstract = {

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 -18 ̊C. 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.

}, keywords = {LTER-MCM}, doi = {10.15760/etd.7237}, url = {https://archives.pdx.edu/ds/psu/30806}, author = {Cross, Julian M. and Andrew G Fountain} } @article {4020, title = {Glaciers in equilibrium, McMurdo Dry Valleys, Antarctica}, journal = {Journal of Glaciology}, volume = {62}, year = {2016}, month = {07/2016}, pages = {976 - 989}, abstract = {

The McMurdo Dry Valleys are a cold, dry polar desert and the alpine glaciers therein exhibit small annual and seasonal mass balances, often \<\±0.06 m w.e. Typically, winter is the accumulation season, but significant snow storms can occur any time of year occasionally making summer the accumulation season. The yearly equilibrium line altitude is poorly correlated with mass balance because the elevation gradient of mass balance on each glacier can change dramatically from year to year. Most likely, winds redistribute the light snowfall disrupting the normal gradient of increasing mass balance with elevation. Reconstructed cumulative mass balance shows that the glaciers have lost \<2 m w.e. over the past half century and area changes show minimal retreat. In most cases these changes are less than the uncertainty and the glaciers are considered in equilibrium. Since 2000, however, the glaciers have lost mass despite relatively stable summer air temperatures suggesting a different mechanism in play. Whether this trend is a harbinger of future changes or a temporary excursion is unclear.

}, keywords = {LTER-MCM, Antarctica, glaciers, mass balance}, issn = {0022-1430}, doi = {10.1017/jog.2016.86}, url = {https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143016000861}, author = {Andrew G Fountain and Hassan J. Basagic and Niebuhr, Spencer} } @article {1086, title = {Garwood Valley, Antarctica: A new record of Last Glacial Maximum to Holocene glaciofluvial processes in the McMurdo Dry Valleys}, journal = {Geological Society of America Bulletin}, volume = {125}, year = {2013}, month = {09/2013}, pages = {1484 - 1502}, keywords = {LTER-MCM}, doi = {10.1130/B30783.1}, url = {http://bulletin.geoscienceworld.org/content/early/2013/06/07/B30783.1.abstract}, author = {Joseph S. Levy and Andrew G Fountain and O{\textquoteright}Connor, J. E. and Kathleen A. Welch and W. Berry Lyons} } @inbook {1213, title = {Glacial ecosystems}, booktitle = {Ecological Monographs}, volume = {78}, year = {2008}, pages = {41-67}, edition = {1}, abstract = {
There is now compelling evidence that microbially mediated reactions impart a significant effect upon the dynamics, composition, and abundance of nutrients in glacial melt water. Consequently, we must now consider ice masses as ecosystem habitats in their own right and address their diversity, functional potential, and activity as part of alpine and polar environments. Although such research is already underway, its fragmentary nature provides little basis for developing modern concepts of glacier ecology. This paper therefore provides a much-needed framework for development by reviewing the physical, biogeochemical, and microbiological characteristics of microbial habitats that have been identified within glaciers and ice sheets. Two key glacial ecosystems emerge, one inhabiting the glacier surface (the supraglacial ecosystem) and one at the ice-bed interface (the subglacial ecosystem). The supraglacial ecosystem is characterized by a diverse consortium of microbes (usually bacteria, algae, phytoflagellates, fungi, viruses and occasional rotifers, tardigrades, and diatoms) within the snowpack, supraglacial streams, and melt pools (cryoconite holes). The subglacial system is dominated by aerobic/anaerobic bacteria and most probably viruses in basal ice/till mixtures and subglacial lakes. A third, so-called englacial ecosystem is also described, but it is demonstrated that conditions within glacier ice are sufficient to make metabolic activity and its impact upon nutrient dynamics negligible at the glacier scale.
Consideration of the surface and internal heat balances of the glacier show that all glacial ecosystems are sensitive to climate change, although at different timescales. Thus, while rapid, melt-driven habitat changes lead to melt-out, resuscitation, and redistribution of microorganisms in many supraglacial ecosystems, much slower climatic and glacial mass-balance processes effect such changes in the subglacial ecosystem. Paradoxically, it is shown that these forces have brought about net refreezing and the onset of cryostasis in the subglacial ecosystems of many Arctic glaciers subject to thinning in recent decades.
}, keywords = {LTER-MCM, Biggie, snow ecology}, doi = {10.1890/07-0187.1}, url = {http://dx.doi.org/10.1890/07-0187.1}, author = {Hodson, A and Alexandre M. Anesio and Martyn Tranter and Andrew G Fountain and Osborn, M and John C. Priscu and Johanna Laybourn-Parry and Sattler, B} } @article {1270, title = {Glacier mass balances (1993-2001) Taylor Valley, McMurdo Dry Valleys, Antarctica}, journal = {Journal of Glaciology}, volume = {52}, year = {2006}, pages = {451}, keywords = {LTER-MCM}, doi = {LTER}, author = {Andrew G Fountain and Thomas H. Nylen and MacClune, K and Gayle L. Dana} } @article {1297, title = {The Geochemistry of Supraglacial Streams of Canada Glacier, Taylor Valley (Antarctica), and their Evolution into Proglacial Waters}, journal = {Aquatic Geochemistry}, volume = {11}, year = {2005}, pages = {391-412}, keywords = {LTER-MCM}, author = {Sarah Fortner and Martyn Tranter and Andrew G Fountain and W. Berry Lyons and Kathleen A. Welch} } @article {1299, title = {Groundwater seeps in Taylor Valley Antarctica: An example of a subsurface melt event}, journal = {Annals of Glaciology}, volume = {40}, year = {2005}, pages = {200-206}, keywords = {LTER-MCM}, doi = {LTER}, author = {W. Berry Lyons and Kathleen A. Welch and Anne E. Carey and Diana H. Wall and Ross A. Virginia and Andrew G Fountain and Peter T. Doran and Csatho, B and Tremper, C} } @article {1364, title = {Glaciers of the McMurdo Dry Valleys: terrestrial analog for Martian polar sublimation}, journal = {Journal of Geophysical Research}, volume = {108}, year = {2003}, pages = {5031}, keywords = {LTER-MCM}, author = {Karen J. Lewis and Andrew G Fountain and Kargel, J and MacAyeal, D} } @inbook {1500, title = {Glaciers of the McMurdo Dry Valleys, Southern Victoria Land, Antarctica}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, series = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {65-75}, keywords = {LTER-MCM}, author = {Andrew G Fountain and Gayle L. Dana and Karen J. Lewis and Bruce H. Vaughn and Diane M. McKnight} } @inbook {1655, title = {Glaciers of the southern hemisphere}, booktitle = {Global and Planetary Change}, volume = {22}, year = {1990}, keywords = {LTER-MCM}, doi = {LTER}, author = {Andrew G Fountain} }