A Review of the Dry Valley Drilling Project, 1971–76

The Dry Valleys of southern Victoria Land, Antarctica, lying some 75 km west of McMurdo station, form an arid, ice-free area of roughly 2 500 km2. Since the late 1950s, this region has provided a remarkable opportunity for geoscientific studies of the exposed surface rocks, within easy reach of logistic support at McMurdo and Scott bases on Ross Island (Fig 1). As a result of a study of Lake Vanda in the Wright Valley, which began during the 1963–64 summer field season, scientists from the United States, New Zealand and Japan supported the view that further advances in our knowledge of the Dry Valleys would require an examination of the unconsolidated material, and the geothermal regime at lake sites, using direct shallow drilling techniques. As drilling techniques and interestin the geological history of the McMurdo region as a whole (encompassing the Transantarctic Mountains, Ross Island, McMurdo Sound and the Dry Valleys) developed, an international, multidisciplinary project—the Dry Valley Drilling Project (DVDP)—was conceived. By 1969 the US National Science Foundation (NSF) had decided to coordinate proposals from scientists wishing to drill the first intermediate and deep cores into the sediment and rock of Antarctica; the aim, a reconstruction of Antarctic geological history that traditional surface or near-surface studies alone could never achieve. Initially, the approach was to be a sub-surface physical, chemical and biological examination of theDry Valleys, but as the project developed it encompassed studies of the Ross Island volcanic complex and McMurdo Sound sediments.

Download Full-text

Near-surface internal melting: a substantial mass loss on Antarctic Dry Valley glaciers

Journal of Glaciology ◽

10.3189/2014jog13j095 ◽

2014 ◽

Vol 60 (220) ◽

pp. 361-374 ◽

Cited By ~ 20

Author(s):

Matthew J. Hoffman ◽

Andrew G. Fountain ◽

Glen E. Liston

Keyword(s):

Meteorological Data ◽

Primary Source ◽

Balance Model ◽

Weathering Crust ◽

Field Observations ◽

Dry Valleys ◽

Near Surface ◽

Ice Surface ◽

Dry Valley ◽

Glacier Ablation

AbstractThe McMurdo Dry Valleys, southern Victoria Land, East Antarctica, are a polar desert, and melt from glacial ice is the primary source of water to streams, lakes and associated ecosystems. Previous work found that to adequately model glacier ablation and subsurface ice temperatures with a surface energy-balance model required including the transmission of solar radiation into the ice. Here we investigate the contribution of subsurface melt to the mass balance of (and runoff from) Dry Valley glaciers by including a drainage process in the model and applying the model to three glacier sites using 13 years of hourly meteorological data. Model results for the smooth glacier surfaces common to many glaciers in the Dry Valleys showed that sublimation was typically the largest component of surface lowering, with rare episodes of surface melting, consistent with anecdotal field observations. Results also showed extensive internal melting 5–15 cm below the ice surface, the drainage of which accounted for ~50% of summer ablation. This is consistent with field observations of subsurface streams and formation of a weathering crust. We identify an annual cycle of weathering crust formation in summer and its removal during the 10 months of winter sublimation.

Download Full-text

A comparison of the high-frequency (>1 Hz) surface and subsurface noise environment at three sites in the United States

Bulletin of the Seismological Society of America ◽

10.1785/bssa0860051516 ◽

1996 ◽

Vol 86 (5) ◽

pp. 1516-1528 ◽

Cited By ~ 4

Author(s):

Christopher J. Young ◽

Eric P. Chael ◽

Mitchell M. Withers ◽

Richard C. Aster

Keyword(s):

United States ◽

Wind Speed ◽

High Frequency ◽

Wind Profile ◽

The United States ◽

Noise Levels ◽

Wind Noise ◽

Near Surface ◽

Unconsolidated Material ◽

Noise Data

Abstract Surface and subsurface high-frequency (>1 Hz) noise data were recorded using nearly identical instrumentation at three widely separated sites in the United States (Amarillo, Texas; Datil, New Mexico; and Pinedale, Wyoming) for extended periods of time under varying wind conditions. While the sites are geologically distinct, the near-surface noise environments have many common features that we believe may be due in large part to the presence of a surficial layer of highly attenuative unconsolidated material at each site. Noise levels seen at or near the surface (5 m or less) are much higher (up to 30 dB) and much more variable (power range up to 44 dB) than those seen at depth (the smallest range was 9 dB for 1951 m at Amarillo). The greatest gains in noise level reduction are realized within the first 100 m and probably much shallower (< ∼ 10 m). Regardless of the wind profile or local lithology, all sites show an excellent correlation between increased noise levels and higher wind speed, even at significant depths (367 m at Amarillo). Wind-generated noise is broadband (at least 15 to 60 Hz) and apparently nonlinear, increasing dramatically when a wind speed threshold is exceeded (3 to 4 m/sec within a few meters of the surface; as high as 8 m/sec at a depth of a few hundred meters). It is possible to be essentially completely shielded from the wind-generated component of seismic noise by deploying instruments at sufficient depth, but we observed this only for the two deepest deployments (1219 and 1951 m, both at Amarillo). Reducing the wind profile at the surface, however, can yield similar reductions for a much smaller cost. Cultural or “workday” noise, if present (depending on the remoteness of the site), is typically much weaker (10 dB or less) than wind noise but may propagate very effectively to great depths and therefore could be of concern for very deep deployments where wind is not a factor.

Download Full-text

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

Antarctic Science ◽

10.1017/s0954102020000619 ◽

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.

Download Full-text

Antarctic Dry Valley Drilling Project: Report on Seminar 1

Eos ◽

10.1029/eo056i004p00217 ◽

1975 ◽

Vol 56 (4) ◽

pp. 217 ◽

Cited By ~ 2

Author(s):

L. McGinnis ◽

T. Torii ◽

R. Clark

Keyword(s):

Project Report ◽

Dry Valley ◽

Drilling Project

Download Full-text

Cryoconite hole connectivity on the Wright Lower Glacier, McMurdo Dry Valleys, Antarctica

Journal of Glaciology ◽

10.1017/jog.2016.62 ◽

2016 ◽

Vol 62 (234) ◽

pp. 714-724 ◽

Cited By ~ 2

Author(s):

SHELLEY MACDONELL ◽

MARTIN SHARP ◽

SEAN FITZSIMONS

Keyword(s):

Spatial Variability ◽

Drainage System ◽

Chloride Content ◽

Mcmurdo Dry Valleys ◽

Hydrological Connectivity ◽

Dry Valleys ◽

Near Surface ◽

Cryoconite Hole ◽

Transfer Method ◽

Surface Ice

ABSTRACTCryoconite holes can be important sources and stores of water and nutrients on cold and polythermal glaciers, and they provide a habitat for various forms of biota. Understanding the hydrological connectivity of cryoconite holes may be the key to understanding the transport of nutrients and biological material to the proglacial areas of such glaciers. This paper aims to characterize and explain spatial variability in the connectivity of ice-lidded cryoconite holes on a small, piedmont glacier in the McMurdo Dry Valleys through geochemical analysis of cryoconite hole waters. Solute concentrations in both surface and near-surface ice and cryoconite holes, vary greatly along the glacier centerline, and all sample types displayed similar spatial patterns of variability. Using chloride as a tracer, we estimated variations in cryoconite hole connectivity along the glacier centerline. We found that a previously used mass transfer method did not provide reliable estimates of the time period for which cryoconite hole waters had been isolated from the atmosphere. We attribute this to spatial variability in both the chloride content of the surface ice and surface ablation rates. The approach may, however, be used to qualitatively characterize spatial variations in the hydrological connectivity of the cryoconite holes. These results also suggest that ice-lidded cryoconite holes are never truly isolated from the near-surface drainage system.

Download Full-text

Long-term trends in aerosol and precipitation composition over the western North Atlantic Ocean at Bermuda

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-7025-2014 ◽

2014 ◽

Vol 14 (5) ◽

pp. 7025-7066 ◽

Cited By ~ 1

Author(s):

W. C. Keene ◽

J. L. Moody ◽

J. N. Galloway ◽

J. M. Prospero ◽

O. R. Cooper ◽

...

Keyword(s):

Atlantic Ocean ◽

North Atlantic ◽

North Atlantic Ocean ◽

Flow Regimes ◽

The United States ◽

Open Ocean ◽

Anthropogenic Sources ◽

Trade Wind ◽

Chemical Compositions ◽

Near Surface

Abstract. Since the 1980s, emissions of SO2 and NOx (NO + NO2) from anthropogenic sources in the United States (US) and Europe have decreased significantly suggesting that the export of oxidized S and N compounds from surrounding continents to the atmosphere overlying North Atlantic Ocean (NAO) has also decreased. The chemical compositions of aerosols and precipitation sampled daily on Bermuda (32.27° N, 64.87° W) from 1989 to 1997 and from 2006 to 2009 were evaluated to quantify the magnitudes, significance, and implications of associated tends in atmospheric composition. The chemical data were stratified based on FLEXPART retroplumes into four discrete transport regimes: westerly flow from the eastern North America (NEUS/SEUS); easterly trade-wind flow from northern Africa and the subtropical NAO (Africa); long, open-ocean, anticyclonic flow around the Bermuda High (Oceanic); and transitional flow from the relatively clean open ocean to the polluted northeastern US (North). Based on all data, annual average concentrations of non-sea-salt (nss) SO42- associated with aerosols and annual VWA concentrations in precipitation decreased significantly (by 22 and 49%, respectively) whereas annual VWA concentrations of NH4+ in precipitation increased significantly (by 70%). Corresponding trends in aerosol and precipitation NO3- and of aerosol NH4+ were insignificant. Nss SO42- in precipitation under NEUS/SEUS and Oceanic flow decreased significantly (61% each) whereas corresponding trends in particulate nss SO42- under both flow regimes were insignificant. Trends for precipitation were driven in part by decreasing emissions of SO2 over upwind continents and associated decreases in anthropogenic contributions to nss SO42- concentrations. Under NEUS/SEUS and Oceanic flow, the ratio of anthropogenic to biogenic contributions to to nss SO42- in the column scavenged by precipitation were relatively greater than those in near surface aerosol, which implies that, for these flow regimes, precipitation is a better indicator of overall anthropogenic impacts on the lower troposphere. Particulate nss SO42- under African flow also decreased significantly (34%) whereas the corresponding decrease in nss SO42- associated with precipitation was marginally insignificant. We infer that these trends were driven in part by reductions in the emissions and transport of oxidized S compounds from Europe. The lack of significant trends in NO3- associated with aerosols and precipitation under NEUS/SEUS flow is notable in light of the large decrease (39%) in NOx emissions in the US over the period of record. Rapid chemical processing of oxidized N in marine air contributed to this lack of correspondence. Decreasing ratios of nss SO42- to NH4+ and the significant decreasing trend in precipitation acidity (37%) indicate that the total amount of acidity in the multiphase gas-aerosol system in the western NAO troposphere decreased over the period of record. Decreasing aerosol acidities would have shifted the phase partitioning of total NH3 (NH3 + particulate NH4+) towards the gas phase thereby decreasing the atmospheric lifetime of total NH3 against wet plus dry deposition. The trend of increasing NH4+ in precipitation at Bermuda over the period of record suggests that NH3 emissions from surrounding continents also increased. Decreasing particulate nss SO42- in near-surface air under NEUS/SEUS flow over the period of record suggests a lower limit for net warming in the range of 0.1–0.3 W m-2 resulting from the decreased shortwave scattering and absorption by nss SO42- and associated aerosol constituents.

Download Full-text

No. 20829. Memorandum of understanding between the United States of America and Japan on participation and cooperation of Japan in the international phase of ocean drilling of the deep sea drilling project. Signed at Tokyo and Washington on 5 August 1980

Treaty Series 1560 - United Nations Treaty Series ◽

10.18356/1f87c682-en-fr ◽

1998 ◽

pp. 539-544

Keyword(s):

United States ◽

United States Of America ◽

Deep Sea ◽

The United States ◽

Ocean Drilling ◽

Drilling Project

Download Full-text

Estimating the Risk of Extreme Wind Gusts in Tropical Cyclones Using Idealized Large-Eddy Simulations and a Statistical-Dynamical Model

Monthly Weather Review ◽

10.1175/mwr-d-21-0059.1 ◽

2021 ◽

Author(s):

Daniel P. Stern ◽

George H. Bryan ◽

Chia-Ying Lee ◽

James D. Doyle

Keyword(s):

Tropical Cyclones ◽

The United States ◽

Large Eddy Simulations ◽

Dynamical Model ◽

Near Surface ◽

Southeastern Us ◽

Wind Gusts ◽

Extreme Wind ◽

Large Eddy

AbstractRecent studies have shown that extreme wind gusts are ubiquitous within the eyewall of intense tropical cyclones (TCs). These gusts pose a substantial hazard to human life and property, but both the short-term (i.e., during the passage of a single TC) and long-term (over many years) risk of encountering such a gust at a given location is poorly understood. Here, simulated tower data from large-eddy simulations of idealized TCs in a quiescent (i.e., no mean flow or vertical wind shear) environment are used to estimate these risks for the offshore region of the United States. For both a category 5 and category 3 TC, there is a radial region where nearly all simulated towers experience near-surface (the lowest 200 m) 3-s gusts exceeding 70 m s−1 within a 10-minute period; on average, these towers respectively sample peak 3-s gusts of 110 and 80 m s−1. Analysis of an observational dropsonde database supports the idealized simulations, and indicates that offshore structures (such as wind turbines) in the eyewall of a major hurricane are likely to encounter damaging wind speeds. This result is then incorporated into an estimate of the long-term risk, using analyses of the return period for major hurricanes from both a best-track database and a statistical-dynamical model forced by reanalysis. For much of the nearshore region of the Gulf of Mexico and southeastern US coasts, this analysis yields an estimate of a 30-60% probability of any given point experiencing at least one 70 m s−1 gust within a 30-year period.

Download Full-text