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.

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 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 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.

scholarly journals Climatic drivers of seasonal glacier mass balances: an analysis of 6 decades at Glacier de Sarennes (French Alps)

2012 ◽  
Vol 6 (3) ◽  
pp. 2115-2160
Author(s):  
E. Thibert ◽  
N. Eckert ◽  
C. Vincent
Keyword(s):  
Mass Balance ◽  
Meteorological Data ◽  
Late Winter ◽  
Equilibrium Line Altitude ◽  
French Alps ◽  
Ice Melt ◽  
Air Temperatures ◽  
Climatic Drivers ◽  
Main Component ◽  
Snow And Ice

Abstract. Refined temporal signals are extracted from a glacier winter and summer mass balance series recorded at Glacier de Sarennes (French Alps) using variance decomposition. They are related to local and synoptic meteorological data in terms of interannual variability and structured trends. The winter balance has increased by +23% since 1976 due to more precipitation in early and late winter. The summer balance has decreased since 1982 due to a 43% increase in snow and ice melt. A 24-day lengthening of the ablation period – mainly due to longer ice ablation – is the main component in the overall increase in ablation. In addition, the last 25 yr have seen increases in ablation rates of 14 and 10% for snow and ice respectively. A simple degree-day analysis can account for both the snow/ice melt rate rise and the lengthening of the ablation period as a function of higher air temperatures. From the same analysis, the equilibrium line altitude of this 45° North latitude south-facing glacier has sensitivity to temperature of +93 m °C−1 around its mean elevation of 3100 m a.s.l. over 6 decades. The sensitivity of summer balance to temperature is −0.62 m w.e. yr−1 °C−1 for a typical 125-day long ablation season. Finally, the time structure of winter and summer mass balance terms are connected to NAO anomalies. Best correlations are obtained with winter NAO anomalies. However, they strongly depend on how the NAO signal is smoothed, so that the link between mass-balance seasonal terms and NAO signal remains tenuous and hard to interpret.

scholarly journals Glacier Mass-Balance Variation in China during the Past Half Century

2018 ◽  
Vol 06 (05) ◽  
pp. 37-58
Author(s):  
Yousif Elnour Yagoub ◽  
Zhongqin Li ◽  
Ahmed A. H. Siddig ◽  
Omer Said Musa ◽  
Muhammad Naveed Anjum
Keyword(s):  
Mass Balance ◽  
Glacier Mass Balance ◽  
Half Century ◽  
The Past ◽  
Past Half Century ◽  
Past Half

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.

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 Geometry change between 1990 and 2003 at Finsterwalderbreen, a Svalbard surge-type glacier, from GPS profiling

2007 ◽  
Vol 46 ◽  
pp. 131-135 ◽  
Author(s):  
Richard Hodgkins ◽  
Adrian Fox ◽  
Anne-Marie Nuttall
Keyword(s):  
Mass Balance ◽  
Phase Evolution ◽  
Mass Gain ◽  
Surface Mass Balance ◽  
Elevation Change ◽  
Equilibrium Line Altitude ◽  
Surface Mass ◽  
Reservoir Area ◽  
Air Temperatures ◽  
Elevation Model

AbstractSurface mass-balance and geometry data are key to quantifying the climate response of glaciers, and confidence in data synthesis and model interpretations and forecasts requires data from as wide a range of locations and glacier types as possible. This paper presents measurements of surface elevation change at the Svalbard surge-type glacier Finsterwalderbreen, by comparing a 1990 digital elevation model (DEM) with a surface GPS profile from 2003. The pattern of elevation change is consistent with that previously noted between 1970 and 1990, and reflects the continued quiescent-phase evolution of the glacier, with mass loss in the down-glacier/receiving area of up to –1.25mw.e. a–1, and mass gain in the up-glacier/reservoir area of up to 0.60 mw.e. a–1; the area-weighted, mean change for the whole glacier is 0.19mw.e. a–1. The spatial pattern of elevation increase and decrease is complex, and the boundary between thickening and thinning determined by combining GPS and DEM data does not appear to correspond with the equilibrium-line altitude determined from surface mass-balance measurements. There is no evidence yet of a decrease in the rate of reservoir area build-up driven by mass-balance change resulting from the warmer winter air temperatures, and decreased proportion of snowfall in total precipitation, noted at meteorological stations in Svalbard.

Cryostratigraphy of mid-Miocene permafrost at Friis Hills, McMurdo Dry Valleys of Antarctica

2020 ◽  
pp. 1-15
Author(s):  
Marjolaine Verret ◽  
Warren Dickinson ◽  
Denis Lacelle ◽  
David Fisher ◽  
Kevin Norton ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Meteoric Water ◽  
Arid Environment ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Ground Ice ◽  
Near Surface ◽  
Air Temperatures ◽  
Drilling Project

Abstract The origin and stability of ground ice in the stable uplands of the McMurdo Dry Valleys remains poorly understood, with most studies focusing on the near-surface permafrost. The 2016 Friis Hills Drilling Project retrieved five cores reaching 50 m depth in mid-Miocene permafrost, a period when Antarctica transitioned to a hyper-arid environment. This study characterizes the cryostratigraphy of arguably the oldest permafrost on Earth and assesses 15 Myr of ground ice evolution using the REGO model. Four cryostratigraphic units were identified: 1) surficial dry permafrost (0–30 cm), 2) ice-rich to ice-poor permafrost (0.3–5.0 m) with high solute load and δ18O values (-16.2 ± 1.8‰) and low D-excess values (-65.6 ± 4.3‰), 3) near-dry permafrost (5–20 m) and 4) ice-poor to ice-rich permafrost (20–50 m) containing ice lenses with low solute load and δ18O values (-34.6 ± 1.2‰) and D-excess of 6.9 ± 2.6‰. The near-surface δ18O profile of ground ice is comparable to other sites in the stable uplands, suggesting that this ice is actively responding to changing surface environmental conditions and challenging the assumption that the surface has remained frozen for 13.8 Myr. The deep ice lenses probably originate from the freezing of meteoric water during the mid-Miocene, and their δ18O composition suggests mean annual air temperatures ~7–11°C warmer than today.

EDITORIAL: Migration and competitiveness: Japan and the United States

2013 ◽  
Vol 10 (2) ◽  
pp. 115-124
Author(s):  
Philip L. Martin
Keyword(s):  
United States ◽  
The United States ◽  
Variable Cost ◽  
Fixed Cost ◽  
Special Issue ◽  
Science And Engineering ◽  
The Past ◽  
Past Half Century ◽  
Key Sectors ◽  
Past Half

Japan and the United States, the world’s largest economies for most of the past half century, have very different immigration policies. Japan is the G7 economy most closed to immigrants, while the United States is the large economy most open to immigrants. Both Japan and the United States are debating how immigrants are and can con-tribute to the competitiveness of their economies in the 21st centuries. The papers in this special issue review the employment of and impacts of immigrants in some of the key sectors of the Japanese and US economies, including agriculture, health care, science and engineering, and construction and manufacturing. For example, in Japanese agriculture migrant trainees are a fixed cost to farmers during the three years they are in Japan, while US farmers who hire mostly unauthorized migrants hire and lay off workers as needed, making labour a variable cost.

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