03241nas a2200505 4500008004100000022001400041245010400055210006900159260001200228300001800240490000700258520177600265653001502041653001302056653001402069653001302083653001902096100002202115700001802137700001602155700002402171700002302195700002302218700001502241700002202256700001802278700002202296700002302318700002402341700002202365700001902387700002302406700001302429700002302442700002102465700002702486700002402513700002302537700001402560700002602574700002002600700003102620700001502651856006902666 2025 eng d a0043-139700aOne-hundred fundamental, open questions to integrate methodological approaches in lake ice research0 aOnehundred fundamental open questions to integrate methodologica c05/2025 ae2024WR0390420 v613 a

The rate of technological innovation within aquatic sciences outpaces the collective ability of individual scientists within the field to make appropriate use of those technologies. The process of in situ lake sampling remains the primary choice to comprehensively understand an aquatic ecosystem at local scales; however, the impact of climate change on lakes necessitates the rapid advancement of understanding and the incorporation of lakes on both landscape and global scales. Three fields driving innovation within winter limnology that we address here are autonomous real-time in situ monitoring, remote sensing, and modeling. The recent progress in low-power in situ sensing and data telemetry allows continuous tracing of under-ice processes in selected lakes as well as the development of global lake observational networks. Remote sensing offers consistent monitoring of numerous systems, allowing limnologists to ask certain questions across large scales. Models are advancing and historically come in different types (process-based or statistical data-driven), with the recent technological advancements and integration of machine learning and hybrid process-based/statistical models. Lake ice modeling enhances our understanding of lake dynamics and allows for projections under future climate warming scenarios. To encourage the merging of technological innovation within limnological research of the less-studied winter period, we have accumulated both essential details on the history and uses of contemporary sampling, remote sensing, and modeling techniques. We crafted 100 questions in the field of winter limnology that aim to facilitate the cross-pollination of intensive and extensive modes of study to broaden knowledge of the winter period.

10acryosphere10alake ice10alimnology10amodeling10aremote sensing1 aCulpepper, Joshua1 aSharma, Sapna1 aGunn, Grant1 aMagee, Madeline, R.1 aMeyer, Michael, F.1 aAnderson, Eric, J.1 aArp, Chris1 aCooley, Sarah, W.1 aDolan, Wayana1 aDugan, Hilary, A.1 aDuguay, Claude, R.1 aJones, Benjamin, M.1 aKirillin, Georgiy1 aLadwig, Robert1 aLeppäranta, Matti1 aLong, Di1 aMagnuson, John, J.1 aPavelsky, Tamlin1 aPiccolroaz, Sebastiano1 aRobertson, Dale, M.1 aSteele, Bethel, G.1 aTom, Manu1 aWeyhenmeyer, Gesa, A.1 aWoolway, Iestyn1 aXenopoulos, Marguerite, A.1 aYang, Xiao uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024WR03904204374nas a2200193 4500008004100000245011900041210006900160260005800229490000900287520367400296653002603970653002403996653002904020653001604049653001904065100002704084700002204111856004704133 2025 eng d00aThe temporal and spatial dynamics of surface sediment on the permanently frozen lakes of Taylor Valley, Antarctica0 atemporal and spatial dynamics of surface sediment on the permane aMadison, WIbUniversity of Wisconsin-Madisonc05/20250 vM.S.3 a

The McMurdo Dry Valleys are the largest unglaciated region of Antarctica and are home to some of the only perennially frozen lakes in the world. The ice covers of the Taylor Valley lakes are subject to decadal-length fluctuations in thickness, largely ranging between three and five meters thick. It has been hypothesized that the changes in ice cover thickness are due to a combination of climate factors and lake ice surface characteristics, but as of yet there have been no studies focusing on interannual dynamics of lake ice albedo by leveraging remote sensing datasets. Landsat 8 imagery was manipulated using spectral mixture analysis to find the abundance of sediment cover across three different Taylor Valley lakes from 2016-2024 during the sunlit period of the year. Peak sediment coverage was not synchronous across years, with Lake Hoare peaking the earliest in 2021, followed by East Lake Bonney and Lake Fryxell in 2023. West Lake Bonney had no apparent peak, although concentrations have declined since 2021. Overall sediment abundance values across all lakes ranged from near 0% to over 75%, though each lake has a different level of sediment coverage. Lake Fryxell and Lake Hoare had the highest mean sediment concentrations, followed by East Lake Bonney, then West Lake Bonney. The relationship between ice thickness and sediment coverage was strongest at Lake Fryxell, followed by East Lake Bonney. Lake Hoare and West Lake Bonney appear to have weaker links between ice thickness and surface sediment, likely driven by differences in overall sediment cover and shading from the surrounding landscape. Ice surface albedo is a historically understudied component of ice physical structure and thermal mechanics and should be more closely considered in future studies predicting ice thickness in the McMurdo Dry Valleys, especially in cases to predict total ice loss. Permanently frozen lakes exhibit unique ice dynamics compared to seasonally freezing lakes, due to their consistent lake ice, where previous years ice conditions have a large effect on ice into the future. The McMurdo Dry Valleys (MDVs), a large unglaciated region in Antarctica, contain many of the few permanently frozen lakes that exist globally. Albedo is a critical factor influencing lake ice mass balance and may strongly govern lake ice thickness. Changes in surface albedo on MDVs lakes occur as a result of aeolian sediment deposition from the surrounding bare soil landscape or physical changes in ice quality throughout the summer, like ice whitening. To investigate the importance of surface characteristics of Taylor Valley lake ice, a one-dimensional thermal diffusion model was developed using in situ meteorological data and a satellite derived ice albedo estimates to simulate ice thickness on East Lake Bonney, Antarctica. Ice thickness was modeled from late 2016 through 2024 using a novel ice albedo dataset, derived from Landsat 8 imagery using linear spectral mixture analysis. Estimated albedo values ranged from 0.5-0.85, covering years when sediment cover was very heavy to very low. Modeled ice thickness was strongly correlated with measured thicknesses. For the period of the year where manual ice thickness measurements are made, modeled ice thicknesses ranged between 2.92-4.16 m, where measured values for that same time span ranged between 3.06-4.19 m. When either increasing or decreasing albedo by 5-10%, mean ice thicknesses diverged by up to 0.8 m. Ice thicknesses are strongly influenced by surface sediment concentrations, and the contribution of a tailored albedo dataset was a valuable input that has historically been over-simplified.

10aaeolian geomorphology10aMcMurdo Dry Valleys10apermanently frozen lakes10apolar lakes10aremote sensing1 aDougherty, Charles, E.1 aDugan, Hilary, A. uhttp://digital.library.wisc.edu/1793/9519401966nas a2200253 4500008004100000022001400041245010100055210006900156260001200225490000700237520119400244653001701438653001301455653002401468653000901492653000901501653002101510100002301531700002401554700002201578700002001600700002101620856007101641 2024 eng d a1523-043000aMeasuring and modelling functional moat area in perennially ice-covered Lake Fryxell, Antarctica0 aMeasuring and modelling functional moat area in perennially icec c10/20240 v563 a

The perennially ice-covered lakes of the McMurdo Dry Valleys (MDVs), Antarctica, are an important reservoir of liquid water in an arid and largely frozen environment. During the austral summer, the margins of these ice covers melt, forming a “moat” of liquid water and thin ice, allowing exchange between lake waters and the atmosphere to occur and serving as an interface between lake, soil, and stream ecosystems. The size of these moats varies from year to year. Here, we have established the first published record of moat area changes at MDVs’ Lake Fryxell through time using manual traces of the moat as observed via satellite imagery. We have also tested a semi-automated approach for measuring moat area and found that it consistently underestimated the manual record, which we suspect may be due to the lower spatial resolution of images used in this versus the manual approach. Finally, we developed a predictive model based on readily available climate data, allowing moat area to be predicted beyond the limits of the satellite-based records. We found that functional moat area varies annually, potentially influencing ecosystem processes in the moats.

10aLake Fryxell10alake ice10aMcMurdo Dry Valleys10amoat10aNDWI10apredictive model1 aStone, Michael, S.1 aSalvatore, Mark, R.1 aDugan, Hilary, A.1 aMyers, Madeline1 aDoran, Peter, T. uhttps://www.tandfonline.com/doi/full/10.1080/15230430.2024.240662602186nas a2200313 4500008004100000022001400041245009000055210006900145260001200214300001800226490000700244520123000251653002201481653002401503653002001527653001701547653001501564100002201579700002101601700002101622700002201643700002201665700002401687700002101711700002501732700002101757700002501778856006901803 2024 eng d a2328-427700aResponse of a terrestrial polar ecosystem to the March 2022 Antarctic weather anomaly0 aResponse of a terrestrial polar ecosystem to the March 2022 Anta c08/2024 ae2023EF0043060 v123 a

Record high temperatures were documented in the McMurdo Dry Valleys, Antarctica, on 18 March 2022, exceeding average temperatures for that day by nearly 30°C. Satellite imagery and stream gage measurements indicate that surface wetting coincided with this warming more than 2 months after peak summer thaw and likely exceeded thresholds for rehydration and activation of resident organisms that typically survive the cold and dry conditions of the polar fall in a freeze-dried state. This weather event is notable in both the timing and magnitude of the warming and wetting when temperatures exceeded 0°C at a time when biological communities and streams have typically entered a persistent frozen state. Such events may be a harbinger of future climate conditions characterized by warmer temperatures and greater thaw in this region of Antarctica, which could influence the distribution, activity, and abundance of sentinel taxa. Here we describe the ecosystem responses to this weather anomaly reporting on meteorological and hydrological measurements across the region and on later biological observations from Canada Stream, one of the most diverse and productive ecosystems within the McMurdo Dry Valleys.

10aatmospheric river10aclimate variability10aextreme weather10apolar desert10asoil biota1 aBarrett, John, E.1 aAdams, Byron, J.1 aDoran, Peter, T.1 aDugan, Hilary, A.1 aMyers, Krista, F.1 aSalvatore, Mark, R.1 aPower, Sarah, N.1 aSnyder, Meredith, D.1 aWright, Anna, T.1 aGooseff, Michael, N. uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023EF00430602505nas a2200325 4500008004100000022001400041245012700055210006900182260001200251300001800263490000800281520146500289653001701754653003701771653002401808653002401832100002701856700002101883700002301904700002201927700002201949700002501971700002001996700002202016700002202038700002202060700002202082700001402104856006102118 2023 eng d a2169-900300aCauses and characteristics of electrical resistivity variability in shallow (<4 m) soils in Taylor Valley, East Antarctica0 aCauses and characteristics of electrical resistivity variability c02/2023 ae2022JF0066960 v1283 a

Airborne electromagnetic surveys collected in December 2011 and November 2018 and three soil sampling transects were used to analyze the spatial heterogeneity of shallow (<4 m) soil properties in lower Taylor Valley (TV), East Antarctica. Soil resistivities from 2011 to 2018 ranged from ∼33 Ωm to ∼3,500 Ωm with 200 Ωm assigned as an upper boundary for brine-saturated sediments. Elevations below ∼50 m above sea level (masl) typically exhibit the lowest resistivities with resistivity increasing at high elevations on steeper slopes. Soil water content was empirically estimated from electrical resistivities using Archie's Law and range from ∼<1% to ∼68% by volume. An increase in silt- and clay-sized particles at low elevations increases soil porosity but decreases hydraulic conductivity, promoting greater residence times of soil water at low elevations near Lake Fryxell. Soil resistivity variability between 2011 and 2018 shows soils at different stages of soil freeze-thaw cycles, which are caused predominantly by solar warming of soils as opposed to air temperature. This study furthers the understanding of the hydrogeologic structure of the shallow subsurface in TV and identifies locations of soils that are potentially prone to greater rates of thaw and resulting ecosystem homogenization of soil properties from projected increases in hydrological connectivity across the region over the coming decades.

10aactive layer10aairborne electromagnetic surveys10aMcMurdo Dry Valleys10apermafrost dynamics1 aGutterman, William, S.1 aDoran, Peter, T.1 aVirginia, Ross, A.1 aBarrett, John, E.1 aMyers, Krista, F.1 aTulaczyk, Slawek, M.1 aFoley, Neil, T.1 aMikucki, Jill, A.1 aDugan, Hilary, A.1 aGrombacher, Denys1 aBording, Thue, S.1 aAuken, E. uhttps://onlinelibrary.wiley.com/doi/10.1029/2022JF00669601629nas a2200217 4500008004100000022001400041245007400055210006900129260001200198300001200210490000600222520097000228100002101198700002201219700002401241700001901265700002101284700002101305700001701326856006801343 2022 eng d a2378-224200aBarotropic seiches in a perennially ice-covered lake, East Antarctica0 aBarotropic seiches in a perennially icecovered lake East Antarct c02/2022 a26 - 330 v73 a

Water movement in ice-covered lakes is known to be driven by wind, sediment heat flux, solar radiation, saline density flows, and advective stream discharge. In large ice-covered lakes, wind-induced oscillations have been found to play a major role in horizontal flows. Here, we report recurrent, wind-driven, barotropic seiches in a small lake with a thick (4 m) permanent ice-cover. Between 2010 and 2016, we recorded 10.5- to 13-min oscillations of the hydrostatic water level in Lake Hoare, McMurdo Dry Valleys, East Antarctica, using pressure transducers moored to the lake bottom and suspended from the ice cover. Theoretical calculations showed a barotropic seiche should have a period of 12.6 min. Barotropic seiches were most frequent during high wind events (> 5 m s-1) in winter months (February–November). The period increased during summer months (December–January) when fast ice thinned and melted along the shoreline.

1 aCastendyk, Devin1 aDugan, Hilary, A.1 aGallagher, Hugh, A.1 aPujara, Nimish1 aDoran, Peter, T.1 aPriscu, John, C.1 aLyons, Berry uhttps://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lol2.1022602152nas a2200253 4500008004100000245012600041210006900167260001200236300001600248490000700264520133900271100002201610700002101632700002501653700002001678700002201698700001701720700002201737700002201759700001901781700002201800700002301822856005301845 2021 eng d00aThermal legacy of a large paleolake in Taylor Valley, East Antarctica, as evidenced by an airborne electromagnetic survey0 aThermal legacy of a large paleolake in Taylor Valley East Antarc c08/2021 a3577 - 35930 v153 a

Previous studies of the lakes of the McMurdo Dry Valleys have attempted to constrain lake level history, and results suggest the lakes have undergone hundreds of meters of lake level change within the last 20 000 years. Past studies have utilized the interpretation of geologic deposits, lake chemistry, and ice sheet history to deduce lake level history; however a substantial amount of disagreement remains between the findings, indicating a need for further investigation using new techniques. This study utilizes a regional airborne resistivity survey to provide novel insight into the paleohydrology of the region. Mean resistivity maps revealed an extensive brine beneath the Lake Fryxell basin, which is interpreted as a legacy groundwater signal from higher lake levels in the past. Resistivity data suggest that active permafrost formation has been ongoing since the onset of lake drainage and that as recently as 1500–4000 years BP, lake levels were over 60 m higher than present. This coincides with a warmer-than-modern paleoclimate throughout the Holocene inferred by the nearby Taylor Dome ice core record. Our results indicate Mid to Late Holocene lake level high stands, which runs counter to previous research finding a colder and drier era with little hydrologic activity throughout the last 5000 years.

1 aMyers, Krista, F.1 aDoran, Peter, T.1 aTulaczyk, Slawek, M.1 aFoley, Neil, T.1 aBording, Thue, S.1 aAuken, Esben1 aDugan, Hilary, A.1 aMikucki, Jill, A.1 aFoged, Nikolaj1 aGrombacher, Denys1 aVirginia, Ross, A. uhttps://tc.copernicus.org/articles/15/3577/2021/00649nas a2200169 4500008004100000022001400041245017800055210006900233260001200302300001600314490000700330100002200337700002300359700002200382700002100404856005400425 2016 eng d a0016-803300aHigh-resolution ground-penetrating radar profiles of perennial lake ice in the McMurdo Dry Valleys, Antarctica: Horizon attributes, unconformities, and subbottom penetration0 aHighresolution groundpenetrating radar profiles of perennial lak c01/2016 aWA13 - WA200 v811 aDugan, Hilary, A.1 aArcone, Steven, A.1 aObryk, Maciek, K.1 aDoran, Peter, T. uhttp://library.seg.org/doi/10.1190/geo2015-0159.101657nas a2200229 4500008004100000245008700041210006900128260001600197300000900213490000600222520097300228100002201201700001401223700001601237700002301253700001701276700002201293700002101315700002201336700001401358856005501372 2015 eng d00aDeep groundwater and potential subsurface habitats beneath an Antarctic dry valley0 aDeep groundwater and potential subsurface habitats beneath an An cApr-04-2017 a68310 v63 aThe occurrence of groundwater in Antarctica, particularly in the ice-free regions and along the coastal margins is poorly understood. Here we use an airborne transient electromagnetic (AEM) sensor to produce extensive imagery of resistivity beneath Taylor Valley. Regional-scale zones of low subsurface resistivity were detected that are inconsistent with the high resistivity of glacier ice or dry permafrost in this region. We interpret these results as an indication that liquid, with sufficiently high solute content, exists at temperatures well below freezing and considered within the range suitable for microbial life. These inferred brines are widespread within permafrost and extend below glaciers and lakes. One system emanates from below Taylor Glacier into Lake Bonney and a second system connects the ocean with the eastern 18 km of the valley. A connection between these two basins was not detected to the depth limitation of the AEM survey (~350 m).1 aMikucki, Jill, A.1 aAuken, E.1 aTulaczyk, S1 aVirginia, Ross, A.1 aSchamper, C.1 aSørensen, K., I.1 aDoran, Peter, T.1 aDugan, Hilary, A.1 aFoley, N. uhttp://www.nature.com/doifinder/10.1038/ncomms783102177nas a2200217 4500008004100000022001300041245014200054210006900196260001600265300001100281490000700292520131900299100002201618700002201640700002401662700002101686700002101707700003301728700002101761856017701782 2014 eng d a0025332400aAutonomous Year-Round Sampling and Sensing to Explore the Physical and Biological Habitability of Permanently Ice-Covered Antarctic Lakes0 aAutonomous YearRound Sampling and Sensing to Explore the Physica cJan-09-2014 a8 - 170 v483 a

The lakes of the McMurdo Dry Valleys, Antarctica, are some of the only systems on our planet that are perennially ice-covered and support year-round metabolism. As such, these ecosystems can provide important information on conditions and life in polar regions on Earth and on other icy worlds in our solar system. Working in these extreme environments of the Dry Valleys poses many challenges, particularly with respect to data collection during dark winter months when logistical constraints make fieldwork difficult. In this paper, we describe the motivation, design, and challenges for this recently deployed instrumentation in Lake Bonney, a lake that has been the subject of summer research efforts for more than 40 years. The instrumentation deployed includes autonomous water, phytoplankton, and sediment samplers as well as cable-mounted profiling platforms with dissolved gas and fluorometry sensors. Data obtained from these instruments will allow us, for the first time, to define the habitability of this environment during the polar night. We include lessons learned during deployment and recommendations for effective instrument operation in these extreme conditions.

1 aWinslow, Luke, A.1 aDugan, Hilary, A.1 aBuelow, Heather, N.1 aCronin, Kyle, D.1 aPriscu, John, C.1 aTakacs-Vesbach, Cristina, D.1 aDoran, Peter, T. uhttp://openurl.ingenta.com/content/xref?genre=article&issn=0025-3324&volume=48&issue=5&spage=8http://www.ingentaconnect.com/content/mts/mtsj/2014/00000048/00000005/art0000202215nas 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

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.

10aAntarctica10abrine10alake ice10aMcMurdo Dry Valleys10apolar lakes10asublimation1 aDugan, Hilary, A.1 aDoran, Peter, T. uhttp://hdl.handle.net/10027/1940700501nas a2200133 4500008004100000245007300041210006900114260001200183490000700195100002200202700002200224700002100246856010000267 2013 eng d00aLake ice ablation rates from permanently ice-covered Antarctic lakes0 aLake ice ablation rates from permanently icecovered Antarctic la c01/20130 v591 aDugan, Hilary, A.1 aObryk, Maciek, K.1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/lake-ice-ablation-rates-permanently-ice-covered-antarctic-lakes