02112nas a2200229   4500008004100000245006600041210006600107260001200173490000700185520130800192653001901500653001901519653002001538653002301558653001301581100002801594700002201622700002201644700002401666700002301690856016901713       2020                        eng d00aModeling present and future ice covers in two Antarctic lakes0 aModeling present and future ice covers in two Antarctic lakes  c02/20200 v663 a<p>Antarctic lakes with perennial ice covers provide the opportunity to investigate in-lake processes without direct atmospheric interaction, and to study their ice-cover sensitivity to climate condi- tions. In this study, a numerical model &ndash; driven by radiative, atmospheric and turbulent heat fluxes from the water body beneath the ice cover &ndash; was implemented to investigate the impact of climate change on the ice covers from two Antarctic lakes: west lobe of Lake Bonney (WLB) and Crooked Lake. Model results agreed well with measured ice thicknesses of both lakes (WLB &ndash; RMSE= 0.11 m over 16 years of data; Crooked Lake &ndash; RMSE= 0.07 m over 1 year of data), and had acceptable results with measured ablation data at WLB (RMSE= 0.28 m over 6 years). The differences between measured and modeled ablation occurred because the model does not consider interannual variability of the ice optical properties and seasonal changes of the lake&rsquo;s thermal structure. Results indicate that projected summer air temperatures will increase the ice-cover annual melting in WLB by 2050, but that the ice cover will remain peren- nial through the end of this century. Contrarily, at Crooked Lake the ice cover becomes ephem- eral most likely due to the increase in air temperatures.</p>10aclimate change10aenergy balance10aice and climate10aice-sheet modeling10alake ice1 aEcheverría, Sebastián1 aHausner, Mark, B.1 aBambach, Nicolás1 aVicuña, Sebastián1 aSuárez, Francisco  uhttps://www.cambridge.org/core/journals/journal-of-glaciology/article/modeling-present-and-future-ice-covers-in-two-antarctic-lakes/9306439ADD5492BC05F3BAF0E076B1C302215nas a2200205   4500008004100000245009200041210006900133260004000202490001000242520158200252653001501834653001001849653001301859653002401872653001601896653001601912100002201928700002101950856003801971       2014                        eng d00aGeophysics, Water Balance, and History of Thick Perennial Ice Covers on Antarctic Lakes0 aGeophysics Water Balance and History of Thick Perennial Ice Cove  aChicago, ILbUniversity of Illinois0 vPh.D.3 a<p>Antarctic lakes are studied as sentinels of future change, for paleolimnological records contained in the sediments, and as habitats for the simple food webs that can exist in inhospitable environments. Understanding how lakes are formed and are sustained in response to landscape and climate conditions is critical in addressing the aforementioned research themes. This thesis is governed by the overarching hypothesis that an understanding of hydrologic and sediment transport processes associated with lake ice formation and preservation can be used to reveal past climatic changes, and further our awareness of current changes in climate and water balance in the McMurdo Dry Valleys of Antarctica. The first chapter focuses on water loss from closed basin lakes in Taylor Valley, Antarctica, and presents updated estimates of sublimation and ablation rates from long-term empirical measurements. The second and third chapters address the formation of Lake Vida, Antarctica. The former investigates the accretion of a 27 m ice cover, and considers the origin of thick sediment layers in the ice cover, and the latter uses two geophysical methods to quantify the extent and volume of the brine network in the subsurface beneath the lake. The results presented herein advance the study of hydrogeology in continuous permafrost, provide additional evidence for fluctuating climate states in the McMurdo Dry Valleys throughout the mid to late Holocene, and provide a case study for the preservation of water in a cold, desert environment analogous to neighboring planets.</p>10aAntarctica10abrine10alake ice10aMcMurdo Dry Valleys10apolar lakes10asublimation1 aDugan, Hilary, A.1 aDoran, Peter, T.  uhttp://hdl.handle.net/10027/19407