@article {4844, title = {Causes and characteristics of electrical resistivity variability in shallow (<4 m) soils in Taylor Valley, East Antarctica}, journal = {Journal of Geophysical Research: Earth Surface}, volume = {128}, year = {2023}, month = {02/2023}, pages = {e2022JF006696}, abstract = {

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\&$\#$39;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.

}, keywords = {LTER-MCM, active layer, airborne electromagnetic surveys, McMurdo Dry Valleys, permafrost dynamics}, issn = {2169-9003}, doi = {10.1029/2022JF006696}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2022JF006696}, author = {Gutterman, William S. and Peter T. Doran and Ross A. Virginia and John E. Barrett and Myers, Krista F. and Tulaczyk, Slawek M. and Foley, Neil T. and Jill A. Mikucki and Hilary A. Dugan and Grombacher, Denys and Bording, Thue S. and Auken, E.} } @article {4843, title = {Extreme cold (-69.1{\textdegree}C) in the McMurdo Dry Valleys}, journal = {Antarctic Science}, volume = {30}, year = {2023}, month = {03/2023}, pages = {1-4}, keywords = {LTER-MCM, climate, extreme, meteorology, temperature, weather}, issn = {0954-1020}, doi = {10.1017/S0954102022000451}, url = {https://www.cambridge.org/core/journals/antarctic-science/article/extreme-cold-691c-in-the-mcmurdo-dry-valleys/3516874750E5EF96365A26E8D49CA4EC}, author = {Peter T. Doran and Myers, Krista F. and Christopher P. McKay and David Bromwich} } @article {4823, title = {Valley-floor snowfall in Taylor Valley, Antarctica, from 1995 to 2017: Spring, summer and autumn}, journal = {Antarctic Science}, volume = {34}, year = {2022}, month = {08/2022}, pages = {325-335}, abstract = {

We present an analysis of the 20 year snowfall dataset in Taylor Valley and the results of a new snow cover monitoring study. Snowfall has been measured at four sites in Taylor Valley from 1995 to 2017. We focus on valley-floor snowfall when wind does not exceed 5 m s-1, and we exclude winter from our analysis due to poor data quality. Snowfall averaged 11 mm water equivalent (w.e.) from 1995 to 2017 across all stations and ranged from 1 to 58 mm w.e. Standard deviations ranged from 3 to 17 mm w.e., highlighting the strong interannual variability of snowfall in Taylor Valley. During spring and autumn there is a spatial gradient in snowfall such that the coast received twice as much snowfall as more central and inland stations. We identified a changepoint in 2007 from increasing snowfall (3 mm w.e. yr-1) to decreasing snowfall (1 mm w.e. yr-1), which coincides with a shift from decreasing temperature to no detectable temperature trend. Daily camera imagery from 2007 to 2017 augments the snowfall measurements. The camera imagery revealed a near tripling of the average number of days with snow cover from 37 days between 2006 and 2012 to 106 days with snow cover between 2012 and 2017.

}, keywords = {LTER-MCM, automated weather station, camera, McMurdo Dry Valleys, snow cover, snow persistence}, doi = {10.1017/S0954102022000256}, url = {https://www.cambridge.org/core/product/identifier/S0954102022000256/type/journal_article}, author = {Myers, Madeline and Peter T. Doran and Myers, Krista F.} } @article {4732, title = {The magnitude and climate sensitivity of isotopic fractionation from ablation of Antarctic Dry Valley lakes}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {53}, year = {2021}, month = {12/2021}, pages = {352 - 371}, abstract = {

There has been extensive research on the effects of evaporation on the isotopic ratio of lacustrine and marine water bodies; however, there are limited data on how ablation or sublimation from lake or sea ice influences the isotopic ratio of the residual water body. This is a challenging problem because there remains uncertainty on the magnitude of fractionation during sublimation and because ablation can involve mixed-phase processes associated with simultaneous sublimation, melting, evaporation, and refreezing. This uncertainty limits the ability to draw quantitative inferences on changing hydrological budgets from stable isotope records in arctic, Antarctic, and alpine lakes. Here, we use in situ measurements of the isotopic ratio of water vapor along with the gradient diffusion method to constrain the isotopic ratio of the ablating ice from two lakes in the McMurdo Dry Valleys, Antarctica. We find that during austral summer, the isotopic fractionation of ablation was insignificant during periods of boundary layer instability that are typical during midday when latent heat is highest. This implies that the loss of mass during these periods did not yield any isotopic enrichment to the residual lake mass. However, fractionation increased after midday when the boundary layer stabilized and the latent heat flux was small. This diurnal pattern was mirrored on synoptic timescales, when following warm and stable conditions latent heat flux was low and dominated by higher fractionation for a few days. We hypothesize that the shifting from negligible to large isotopic fractionation reflects the development and subsequent exhaustion of liquid water on the surface. The results illustrate the complex and nonlinear controls on isotopic fractionation from icy lakes, which implies that the isotopic enrichment from ablation could vary significantly over timescales relevant for changing lake volumes. Future work using water isotope fluxes for longer periods of time and over additional perennial and seasonal ice-covered lake systems is critical for developing models of the isotopic mass balance of arctic and Antarctic lake systems.

}, keywords = {LTER-MCM, Dry Valley lakes, isotope fractionation, stable water isotopes}, issn = {1523-0430}, doi = {10.1080/15230430.2021.2001899}, url = {https://www.tandfonline.com/doi/full/10.1080/15230430.2021.2001899}, author = {Bellagamba, Anthony W. and Berkelhammer, Max and Winslow, Luke A. and Peter T. Doran and Myers, Krista F. and Devlin, Shawn and Ian Hawes} } @article {4647, title = {Thermal legacy of a large paleolake in Taylor Valley, East Antarctica, as evidenced by an airborne electromagnetic survey}, journal = {The Cryosphere}, volume = {15}, year = {2021}, month = {08/2021}, pages = {3577 - 3593}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.5194/tc-15-3577-2021}, url = {https://tc.copernicus.org/articles/15/3577/2021/}, author = {Myers, Krista F. and Peter T. Doran and Tulaczyk, Slawek M. and Foley, Neil T. and Bording, Thue S. and Auken, Esben and Hilary A. Dugan and Jill A. Mikucki and Foged, Nikolaj and Grombacher, Denys and Ross A. Virginia} } @article {4613, title = {Year-round and long-term phytoplankton dynamics in Lake Bonney, a permanently ice-covered Antarctic lake}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {126}, year = {2021}, month = {04/2021}, pages = {e2020JG005925}, abstract = {

Lake Bonney (McMurdo Dry Valleys, east Antarctica) represents a year-round refugium for life adapted to permanent extreme conditions. Despite intensive research since the 1960s, due to the logistical constraints posed by 4-months of 24-h darkness, knowledge of how the resident photosynthetic microorganisms respond to the polar winter is limited. In addition, the lake level has risen by more than 3 m since 2004: impacts of rapid lake level rise on phytoplankton community structure is also poorly understood. From 2004 to 2015 an in situ submersible spectrofluorometer (bbe FluoroProbe) was deployed in Lake Bonney during the austral summer to quantify the vertical structure of four functional algal groups (green algae, mixed algae, and cryptophytes, cyanobacteria). During the 2013\–2014 field season the Fluoroprobe was mounted on autonomous cable-crawling profilers deployed in both the east and west lobes of Lake Bonney, obtaining the first daily phytoplankton profiles through the polar night. Our findings showed that phytoplankton communities were differentially impacted by physical and chemical factors over long-term versus seasonal time scales. Following a summer of rapid lake level rise (2010\–2011), an increase in depth integrated chlorophyll a (chl-a) occurred in Lake Bonney caused by stimulation of photoautotrophic green algae. Conversely, peaks in chl-a during the polar night were associated with an increase in mixotrophic haptophytes and cryptophytes. Collectively our data reveal that phytoplankton groups possessing variable trophic abilities are differentially competitive during seasonal and long-term time scales owing to periods of higher nutrients (photoautotrophs) versus light/energy limitation (mixotrophs).

}, keywords = {LTER-MCM, algae, Antarctic, fluorometry, ice, lakes, light, profiling, winter}, issn = {2169-8953}, doi = {10.1029/2020JG005925}, url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JG005925}, author = {Patriarche, Jeffrey D. and John C. Priscu and Cristina D. Takacs-Vesbach and Winslow, Luke A. and Myers, Krista F. and Heather N. Buelow and Rachael M. Morgan-Kiss and Peter T. Doran} } @mastersthesis {4364, title = {Groundwater and thermal legacy of a large paleolake in Taylor Valley, East Antarctica as evidenced by airborne electromagnetic and sedimentological techniques}, volume = {M.S.}, year = {2018}, month = {07/2018}, school = {Louisiana State University}, type = {masters}, address = {Baton Rouge, LA}, abstract = {

During the Last Glacial Maximum, grounded ice in the Ross Sea extended into the otherwise ice-free McMurdo Dry Valleys, creating a series of large ice dammed paleolakes. Grounded ice within the mouth of Taylor Valley allowed for lake levels to reach elevations not possible at modern day and formed what is known as Glacial Lake Washburn (GLW). GLW extended from the eastern portion of Taylor Valley roughly 20 km west to a level ~300 m higher than modern day Lake Fryxell. The formation and existence of GLW has been debated, though previous studies correlate the timing of GLW with early Holocene grounded ice. Evidence of GLW has largely been constrained to the interpretation of glacial deposits and fluvial features such as lacustrine deposits, strandlines, and preserved paleodeltas. GIS and remote sensing techniques paired with regional resistivity data provide new insight into the paleohydrology of the region.

To quantify the extent of GLW, paleodelta locations were mapped using high resolution LiDAR digital elevation models and satellite imagery. Delta topset elevations were correlated between three streams in Fryxell basin to determine paleolake levels. Additionally, mean resistivity maps generated from airborne electromagnetic survey data (SkyTEM) reveal an extensive groundwater system within Fryxell basin which is interpreted as a legacy groundwater signal from GLW. Resistivity data suggests that active permafrost formation has been ongoing since onset of lake drainage, and that lake levels were over 60 m higher than modern only 1,000 \– 2,000 yr BP. This coincides with a warmer than modern paleoclimate inferred by ice core records, indicating a dynamic hydrological system that is highly sensitive to small changes in climate. As global temperatures increase, Lake Fryxell will continue to experience highly variable lake levels. Lakes and groundwater within the McMurdo Dry Valleys are critical to understanding impacts on the broader ecosystem which is largely driven by the availability of liquid water.

}, keywords = {LTER-MCM}, url = {https://digitalcommons.lsu.edu/gradschool_theses/4776}, author = {Myers, Krista F. and Peter T. Doran} }