scholarly journals Glacier mass balances (1993–2001), Taylor Valley, McMurdo Dry Valleys, Antarctica

2006 ◽  
Vol 52 (178) ◽  
pp. 451-462 ◽  
Author(s):  
Andrew G. Fountain ◽  
Thomas H. Nylen ◽  
Karen L. MacClune ◽  
Gayle L. Dana
Keyword(s):  
Mass Balance ◽  
Piecewise Linear ◽  
Objective Assessment ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Mass Balances ◽  
Missing Measurements ◽  
Wind Speeds ◽  
Taylor Valley ◽  
Air Temperatures

AbstractMass balances were measured on four glaciers in Taylor Valley, Antarctica, from 1993 to 2001. We used a piecewise linear regression, which provided an objective assessment of error, to estimate the mass balance with elevation. Missing measurements were estimated from linear regressions between points and showed a significant improvement over other methods. Unlike temperate glaciers the accumulation zone of these polar glaciers accumulates mass in summer and winter and the ablation zone loses mass in both seasons. A strong spatial trend of smaller mass-balance values with distance inland (r2 = 0.80) reflects a climatic gradient to warmer air temperatures, faster wind speeds and less precipitation. Annual and seasonal mass-balance values range only several tens of millimeters in magnitude and no temporal trend is evident. The glaciers of Taylor Valley, and probably the entire McMurdo Dry Valleys, are in equilibrium with the current climate, and contrast with glacier trends elsewhere on the Antarctic Peninsula and in temperate latitudes.

scholarly journals Glaciers in equilibrium, McMurdo Dry Valleys, Antarctica

2016 ◽  
Vol 62 (235) ◽  
pp. 976-989 ◽  
Author(s):  
ANDREW G. FOUNTAIN ◽  
HASSAN J. BASAGIC ◽  
SPENCER NIEBUHR
Keyword(s):  
Mass Balance ◽  
Elevation Gradient ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Equilibrium Line Altitude ◽  
Air Temperatures ◽  
Past Half Century ◽  
Time Of Year ◽  
Snow Storms ◽  
Past Half

ABSTRACTThe 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.

Spatial variations in the geochemistry of glacial meltwater streams in the Taylor Valley, Antarctica

2010 ◽  
Vol 22 (6) ◽  
pp. 662-672 ◽  
Author(s):  
Kathleen A. Welch ◽  
W. Berry Lyons ◽  
Carla Whisner ◽  
Christopher B. Gardner ◽  
Michael N. Gooseff ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Freezing Point ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Stream Chemistry ◽  
Glacial Meltwater ◽  
Taylor Valley ◽  
Air Temperatures ◽  
Wide Range ◽  
Long Term Ecological Research

AbstractStreams in the McMurdo Dry Valleys, Antarctica, flow during the summer melt season (4–12 weeks) when air temperatures are close to the freezing point of water. Because of the low precipitation rates, streams originate from glacial meltwater and flow to closed-basin lakes on the valley floor. Water samples have been collected from the streams in the Dry Valleys since the start of the McMurdo Dry Valleys Long-Term Ecological Research project in 1993 and these have been analysed for ions and nutrient chemistry. Controls such as landscape position, morphology of the channels, and biotic and abiotic processes are thought to influence the stream chemistry. Sea-salt derived ions tend to be higher in streams that are closer to the ocean and those streams that drain the Taylor Glacier in western Taylor Valley. Chemical weathering is an important process influencing stream chemistry throughout the Dry Valleys. Nutrient availability is dependent on landscape age and varies with distance from the coast. The streams in Taylor Valley span a wide range in composition and total dissolved solids and are surprisingly similar to a wide range of much larger temperate and tropical river systems.

scholarly journals A temperature-index model of stream flow at below-freezing temperatures in Taylor Valley, Antarctica

2005 ◽  
Vol 40 ◽  
pp. 76-82 ◽  
Author(s):  
Amy F. Ebnet ◽  
Andrew G. Fountain ◽  
Thomas H. Nylen ◽  
Diane M. Mcknight ◽  
Christopher L. Jaros
Keyword(s):  
Melting Rate ◽  
Coefficient Of Determination ◽  
Dry Valleys ◽  
The South ◽  
Index Model ◽  
The North ◽  
Taylor Valley ◽  
Air Temperatures ◽  
Glacial Runoff ◽  
Summer Temperatures

AbstractWe model runoff from glaciers in the McMurdo Dry Valleys, Antarctica, with summer (December–January) average air temperatures from 1990 to 2002 for the purpose of estimating decades- to millennial-scale glacial runoff into Lakes Fryxell, Hoare and Bonney. The relationship between summer temperatures and melt is found to be exponential near the melting temperature. We propose a variety of simple models that are calibrated using measured discharge from a number of streams draining from ten glaciers in Taylor Valley. The surface melting rate is constrained by mass-balance measurements from four of the glaciers. A model based solely on temperature produced good results (coefficient of determination, r2 = 0.71) for the south-facing glaciers, but poor results for the north-facing glaciers (r2 < 0). The inclusion of a solar radiation index increased the modeled melt from the north-facing glaciers and thus improved the results (r2 = 0.73) for the north-facing glaciers, with little change from the south-facing glaciers. Including a wind index did not improve the correlation between modeled and measured runoff.

scholarly journals An englacial hydrologic system of brine within a cold glacier: Blood Falls, McMurdo Dry Valleys, Antarctica

2017 ◽  
Vol 63 (239) ◽  
pp. 387-400 ◽  
Author(s):  
JESSICA A. BADGELEY ◽  
ERIN C. PETTIT ◽  
CHRISTINA G. CARR ◽  
SLAWEK TULACZYK ◽  
JILL A. MIKUCKI ◽  
...  
Keyword(s):  
Latent Heat ◽  
Flow Direction ◽  
Salt Content ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Outlet Glacier ◽  
Air Temperatures ◽  
Radio Echo Sounding ◽  
Hydrologic System ◽  
Taylor Glacier

ABSTRACTTaylor Glacier hosts an active englacial hydrologic system that feeds Blood Falls, a supraglacial outflow of iron-rich subglacial brine at the terminus, despite mean annual air temperatures of −17°C and limited surface melt. Taylor Glacier is an outlet glacier of the East Antarctic ice sheet that terminates in Lake Bonney, McMurdo Dry Valleys. To image and map the brine feeding Blood Falls, we used radio echo sounding to delineate a subhorizontal zone of englacial brine upstream from Blood Falls and elongated in the ice flow direction. We estimate volumetric brine content in excess of 13% within 2 m of the central axis of this zone, and likely much higher at its center. Brine content decreases, but remains detectable, up to 45 m away along some transects. Hence, we infer a network of subparallel basal crevasses allowing injection of pressurized subglacial brine into the ice. Subglacial brine is routed towards Blood Falls by hydraulic potential gradients associated with deeply incised supraglacial valleys. The brine remains liquid within the subglacial and englacial environments through latent heat of freezing coupled with elevated salt content. Our findings suggest that cold glaciers could support freshwater hydrologic systems through localized warming by latent heat alone.

Experimental formation of pore fluids in McMurdo Dry Valleys soils

2014 ◽  
Vol 27 (2) ◽  
pp. 163-171 ◽  
Author(s):  
Joseph Levy ◽  
Andrew Fountain ◽  
W. Berry Lyons ◽  
Kathy Welch
Keyword(s):  
Relative Humidity ◽  
Salt Content ◽  
Soil Samples ◽  
Mcmurdo Dry Valleys ◽  
Absolute Amount ◽  
Dry Valleys ◽  
Pore Waters ◽  
Taylor Valley ◽  
Experimental Formation ◽  
Laboratory Analogue

AbstractThe aim of the study was to determine if soil salt deliquescence and brine hydration can occur under laboratory conditions using natural McMurdo Dry Valleys soils. The experiment was a laboratory analogue for the formation of isolated patches of hypersaline, damp soil, referred to as ‘wet patches’. Soils were oven dried and then hydrated in one of two humidity chambers: one at 100% relative humidity and the second at 75% relative humidity. Soil hydration is highly variable, and over the course of 20 days of hydration, ranged from increases in water content by mass from 0–16% for 122 soil samples from Taylor Valley. The rate and absolute amount of soil hydration correlates well with the soluble salt content of the soils but not with grain size distribution. This suggests that the formation of bulk pore waters in these soils is a consequence of salt deliquescence and hydration of the brine from atmospheric water vapour.

scholarly journals Extreme southern locations for moss sporophytes in Antarctica

1992 ◽  
Vol 4 (1) ◽  
pp. 37-39 ◽  
Author(s):  
R.D. Seppelt ◽  
T.G.A. Green ◽  
A-M.J. Schwarz ◽  
A. Frost
Keyword(s):  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Southern Limit ◽  
Taylor Valley ◽  
Victoria Land

Abundant immature sporophytes of the moss Pottia heimii are reported from the Lower Taylor Valley, McMurdo Dry Valleys and from Cape Chocolate, Victoria Land. These finds extend the reported southern limit for the occurrence of abundant moss sporophytes to 77° 55′S.

scholarly journals Lake ice ablation rates from permanently ice-covered Antarctic lakes

2013 ◽  
Vol 59 (215) ◽  
pp. 491-498 ◽  
Author(s):  
H.A. Dugan ◽  
M.K. Obryk ◽  
P.T. Doran
Keyword(s):  
Ice Cover ◽  
Mcmurdo Dry Valleys ◽  
Meteorological Variables ◽  
Dry Valleys ◽  
Lake Ice ◽  
Antarctic Lakes ◽  
Closed Basin ◽  
Taylor Valley ◽  
Surface Melt

AbstractIn the McMurdo Dry Valleys of Antarctica, three large, permanently ice-covered, closed-basin lakes exist along the floor of Taylor Valley. Lake ice ablation (loss of ice mass) is calculated as the sum of sublimation and surface melt, and is the driver of ice-cover turnover in these systems. In Taylor Valley, both manual and automated lake ice ablation rates have been calculated from 2001 to 2011. Results indicate relatively consistent winter ablation of 0.07–0.21 m (0.2–0.7 mm w.e. d−1). Summer ablation of lake ice is more variable and ranges from 0.25 to 1.62 m (5–31 mm w.e. d−1) over an average 51 day period. Previous to this study, ablation rates have been cited as 0.35 m a−1in the dry valleys from sublimation modeling based on meteorological variables. We show that this value has significantly underestimated mean ablation and ice-cover turnover on the Taylor Valley lakes.

scholarly journals Climatic implications of reconstructed early–mid Pliocene equilibrium-line altitudes in the McMurdo Dry Valleys, Antarctica

2009 ◽  
Vol 50 (50) ◽  
pp. 31-36 ◽  
Author(s):  
A.G. Krusic ◽  
M.L. Prentice ◽  
J.M. Licciardi
Keyword(s):  
Mass Balance ◽  
Mcmurdo Dry Valleys ◽  
Equilibrium Line ◽  
Ratio Method ◽  
Dry Valleys ◽  
Climate Regime ◽  
Equilibrium Line Altitude ◽  
Alpine Glaciers

AbstractEarly–mid Pliocene moraines in the McMurdo Dry Valleys, Antarctica, are more extensive than the present alpine glaciers in this region, indicating substantial climatic differences between the early–mid Pliocene and the present. To quantify this difference in the glacier–climate regime, we estimated the equilibrium-line altitude (ELA) change since the early–mid Pliocene by calculating the modern ELA and reconstructing the ELAs of four alpine glaciers in Wright and Taylor Valleys at their early–mid Pliocene maxima. The area–altitude balance ratio method was used on modern and reconstructed early–mid Pliocene hypsometry. In Wright and Victoria Valleys, mass-balance data identify present-day ELAs of 800–1600ma.s.l. and an average balance ratio of 1.1. The estimated ELAs of the much larger early–mid Pliocene glaciers in Wright and Taylor Valleys range from 600 to 950±170ma.s.l., and thus are 250–600±170m lower than modern ELAs in these valleys. The depressed ELAs during the early–mid-Pliocene most likely indicate a wetter and therefore warmer climate in the Dry Valleys during this period than previous studies have recognized.

scholarly journals Water tracks intensify surface energy and mass exchange in the Antarctic McMurdo Dry Valleys

2019 ◽  
Author(s):  
Tobias Linhardt ◽  
Joseph S. Levy ◽  
Christoph K. Thomas
Keyword(s):  
Climate Change ◽  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Heat Fluxes ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Sensible Heat ◽  
Taylor Valley ◽  
The Antarctic

Abstract. We evaluated the hypotheses that water tracks alter the surface energy balance in the Antarctic McMurdo Dry Valleys and may serve as an indicator of landscape response to climate change in this dry, cold and ice-sheet-free environment. Water tracks are channel-shaped high moisture zones in the active layer of polar soils. The surface energy balance was measured for one water-track and two non-water-track reference locations in Taylor Valley during the Antarctic summer of 2012–2013. Turbulent atmospheric fluxes of sensible heat and evaporation were observed using the eddy-covariance method in combination with flux footprint modeling, which was the first application of this state-of-the-art technique in the Dry Valleys. Soil heat fluxes were analyzed separately for thawed and frozen layers at all locations via computing the change of the heat storage in the thawed layer from measurements. The results showed that for both water track and reference locations over 50 % of the net radiation was transferred to sensible heat exchange, about 30 % to melting the seasonally thawed layer, and the remainder to evaporation. The net energy flux in the thawed layer was zero. For the water track location, evaporation was increased by a factor of 3.0 relative to the references, ground heat fluxes by 1.4, and net radiation by 1.1, while sensible heat fluxes were reduced down to 0.7. Entertaining a realistic scenario of climate change in Taylor Valley in which the land cover fraction of water tracks increases by 50 %, the total evaporation from lower Taylor Valley would increase by 4 % to 0.30 mm d−1. In summary, our findings show that water tracks have a strong impact on the surface energy balance in ice-sheet free Antarctic regions. Water tracks are hot spots of change and are likely to respond faster to climate change signals than the dominant dry glacial till in the McMurdo Dry Valleys. Their spatiotemporal dynamics may therefore serve as indicator of high-sensitivity for change in permafrost-dominated cold landscapes.

scholarly journals The climate history of early Mars: insights from the Antarctic McMurdo Dry Valleys hydrologic system

2014 ◽  
Vol 26 (6) ◽  
pp. 774-800 ◽  
Author(s):  
James W. Head ◽  
David R. Marchant
Keyword(s):  
Ground Surface ◽  
Volcanic Eruptions ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Climate History ◽  
Air Temperatures ◽  
Hydrological System ◽  
Hydrologic System ◽  
Early Mars ◽  
Geologic Record

AbstractThe early climate of Mars (Noachian Period, the first ~20% of its history) is thought to differ significantly from that of its more recent history (Amazonian Period, the last ~66%) which is characterized by hyperarid, hypothermal conditions that result in mean annual air temperatures (MAAT) well below 0°C, a global cryosphere, minimal melting on the ground surface, and a horizontally stratified hydrologic system. We explore the nature of the fluvial and lacustrine environments in the Mars-like hyperarid, hypothermal McMurdo Dry Valleys (MDV), where the MAAT is well below 0°C (~ -14 to -30°C) in order to assess whether the Late Noachian geologic record can be explained by a climate characterized by “cold and icy” conditions. We find that the MDV hydrological system and cycle provide important insights into the potential configuration of a “cold and icy” early Mars climate in which MDV-like ephemeral streams and rivers, and both closed-basin and open-basin lakes could form. We review a series of MDV fluvial and lacustrine features to guide investigators in the analysis of the geomorphology of early Mars and we outline a new model for the nature and evolution of a “cold and icy” Late Noachian climate based on these observations. We conclude that a cold and icy Late Noachian Mars with MAAT below freezing, but peak seasonal and peak daily temperatures above 0°C, could plausibly account for the array of Noachian-aged fluvial and lacustrine features observed on Mars. Our assessment also provides insight into the potential effects of punctuated warming on a cold and icy early Mars, in which impact crater formation or massive volcanic eruptions cause temperatures in the melting range for decadal to centennial timescales. We outline a set of outstanding questions and tests concerning the nature and evolution of these features on Mars.

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