scholarly journals Instruments and methods: hot-water borehole drilling at a high-elevation debris-covered glacier

2019 ◽  
Vol 65 (253) ◽  
pp. 822-832
Author(s):  
Katie E. Miles ◽  
Evan S. Miles ◽  
Bryn Hubbard ◽  
Duncan J. Quincey ◽  
Ann V. Rowan ◽  
...  
Keyword(s):  
Numerical Models ◽  
Atmospheric Oxygen ◽  
High Elevation ◽  
Hot Water ◽  
Direct Access ◽  
Transport Capacity ◽  
Capacity Limits ◽  
Ice Surface ◽  
Drilling Equipment ◽  
Established Technique

AbstractWhile hot-water drilling is a well-established technique used to access the subsurface of ice masses, drilling into high-elevation (≳ 4000 m a.s.l.) debris-covered glaciers faces specific challenges. First, restricted transport capacity limits individual equipment items to a volume and mass that can be slung by small helicopters. Second, low atmospheric oxygen and pressure reduces the effectiveness of combustion, limiting a system's ability to pump and heat water. Third, thick supraglacial debris, which is both highly uneven and unstable, inhibits direct access to the ice surface, hinders the manoeuvring of equipment and limits secure sites for equipment placement. Fourth, englacial debris can slow the drilling rate such that continued drilling becomes impracticable and/or boreholes deviate substantially from vertical. Because of these challenges, field-based englacial and subglacial data required to calibrate numerical models of high-elevation debris-covered glaciers are scarce or absent. Here, we summarise our experiences of hot-water drilling over two field seasons (2017–2018) at the debris-covered Khumbu Glacier, Nepal, where we melted 27 boreholes up to 192 m length, at elevations between 4900 and 5200 m a.s.l. We describe the drilling equipment and operation, evaluate the effectiveness of our approach and suggest equipment and methodological adaptations for future use.

A MULTI-TRACER APPROACH COUPLED TO NUMERICAL MODELS TO IMPROVE UNDERSTANDING OF MOUNTAIN BLOCK PROCESSES IN A HIGH ELEVATION, SEMI-HUMID CATCHMENT

2016 ◽  
Author(s):  
Ravindra Dwivedi ◽  
◽  
Thomas Mexiner ◽  
Thomas Mexiner ◽  
Jennifer C. McIntosh ◽  
...  
Keyword(s):  
Numerical Models ◽  
High Elevation

Initial results from International Thwaites Glacier Collaboration cruise NBP20-02

2020 ◽  
Author(s):  
Robert Larter ◽  
Julia Wellner ◽  
Alastair Graham ◽  
Claus-Dieter Hillenbrand ◽  
Kelly Hogan ◽  
...  
Keyword(s):  
Sea Level ◽  
Numerical Models ◽  
Sediment Cores ◽  
Hot Water ◽  
Seismic Profiles ◽  
Ice Shelf ◽  
Regional Survey ◽  
Amundsen Sea ◽  
Marine Research ◽  
Initial Results

<p>Thwaites Glacier (TG) is more vulnerable to unstable retreat than any other part of the West Antarctic Ice Sheet. This is due to its upstream-dipping bed, the absence of a large ice shelf buttressing its flow and the deep bathymetric troughs that route relatively warm Circumpolar Deep Water (CDW) to its margin. Over the past 30 years the mass balance of TG has become increasingly negative, suggesting that unstable retreat may have already begun. The International Thwaites Glacier Collaboration (ITGC) is an initiative jointly funded by the US National Science Foundation and the Natural Environment Research Council in the UK to improve knowledge of the boundary conditions and drivers of change at TG in order improve projections of its future contribution to sea level. The ITGC is funding a range of projects that are conducting on-ice and marine research, and applying numerical models to utilize results in order to predict how the glacier will change and contribute to sea level over coming decades to centuries.</p><p>RV Nathaniel B Palmer cruise NBP20-02, taking place from January­ to March 2020, will be the second ITGC multi-disciplinary research cruise, building on results from NBP19-02, which took place last year. Thwaites Offshore Research Project (THOR) aims during NBP20-02 include: extending the bathymetric survey in front of TG, collecting sediment cores at sites selected from the survey data, and acquiring high-resolution seismic profiles to determine the properties of the former bed of TG that is now exposed. The detailed bathymetric data will reveal the dimensions and routing of troughs that conduct CDW to the glacier front and will image seabed landforms that provide information about past ice flow and processes at the bed when TG was more extensive. The sediment cores, together with ones collected recently beneath the ice shelf via hot-water drilled holes, will be analysed to establish a history of TG retreat, subglacial meltwater release, and CDW incursions extending back over decades, centuries and millennia before the short instrumental record. Thwaites-Amundsen Regional Survey and Network Project (TARSAN) researchers will reach islands and ice floes via zodiac boats to attach satellite data relay loggers to Elephant and Weddell seals. The loggers record ocean temperature and salinity during the seals’ dives, greatly increasing the spatial extent and time span of oceanographic observations. In addition to work that is part of the THOR and TARSAN projects, another cruise objective is to recover and redeploy long-term oceanographic moorings in the Amundsen Sea. We will present initial results from NBP20-02.</p>

scholarly journals Reanalysis of 47 Years of Climate in the French Alps (1958–2005): Climatology and Trends for Snow Cover

2009 ◽  
Vol 48 (12) ◽  
pp. 2487-2512 ◽  
Author(s):  
Yves Durand ◽  
Gérald Giraud ◽  
Martin Laternser ◽  
Pierre Etchevers ◽  
Laurent Mérindol ◽  
...  
Keyword(s):  
Snow Cover ◽  
Snow Depth ◽  
Numerical Models ◽  
High Elevation ◽  
Climatic Conditions ◽  
Spatial And Temporal Variability ◽  
The South ◽  
French Alps ◽  
Mountainous Regions ◽  
The North

Abstract Since the early 1990s, Météo-France has used an automatic system combining three numerical models to simulate meteorological parameters, snow cover stratigraphy, and avalanche risk at various altitudes, aspects, and slopes for a number of mountainous regions (massifs) in the French Alps and the Pyrenees. This Système d’Analyse Fournissant des Renseignements Atmosphériques à la Neige (SAFRAN)–Crocus–Modèle Expert de Prévision du Risque d’Avalanche (MEPRA) model chain (SCM), usually applied to operational daily avalanche forecasting, is here used for retrospective snow and climate analysis. For this study, the SCM chain used both meteorological observations and guess fields mainly issued from the newly reanalyzed atmospheric model 40-yr ECMWF Re-Analysis (ERA-40) data and ran on an hourly basis over a period starting in the winter of 1958/59 until recent past winters. Snow observations were finally used for validation, and the results presented here concern only the main climatic features of the alpine modeled snowfields at different spatial and temporal scales. The main results obtained confirm the very significant spatial and temporal variability of the modeled snowfields with regard to certain key parameters such as those describing ground coverage or snow depth. Snow patterns in the French Alps are characterized by a marked declining gradient from the northwestern foothills to the southeastern interior regions. This applies mainly to both depths and durations, which exhibit a maximal latitudinal variation at 1500 m of about 60 days, decreasing strongly with the altitude. Enhanced at low elevations, snow depth shows a mainly negative temporal variation over the study period, especially in the north and during late winters, while the south exhibits more smoothed features. The number of days with snow on the ground shows also a significant general signal of decrease at low and midelevation, but this signal is weaker in the south than in the north and less visible at high elevation. Even if a statistically significant test cannot be performed for all elevations and areas, the temporal decrease is present in all the studied quantities. Concerning snow duration, this general decrease can also be interpreted as a sharp variation of the mean values at the end of the 1980s, inducing a step effect in its time series rather than a constant negative temporal trend. The results have also been interpreted in terms of potential for a viable ski industry, especially in the southern areas, and for different changing climatic conditions. Presently, French downhill ski resorts are economically viable from a range of about 1200 m MSL in the northern foothills to 2000 m in the south, but future prospects are uncertain. In addition, no clear and direct relationship between the North Atlantic Oscillation (NAO) or the ENSO indexes and the studied snow parameters could be established in this study.

Calculations of Scald Burns: Effects of Water Temperature, Exposure Duration, and Clothing

2010 ◽  
Author(s):  
Nessa Johnson ◽  
John Abraham ◽  
Zach Helgeson
Keyword(s):  
Elevated Temperatures ◽  
Burn Injury ◽  
Tissue Injury ◽  
Numerical Models ◽  
Blood Perfusion ◽  
Visual Observation ◽  
Hot Water ◽  
Appropriate Treatment ◽  
Direct Exposure ◽  
Temperature Exposure

A numerical model has been constructed to assess the depth of injury incurred when skin is exposed to heated water. The model includes an extended duration which occurs when clothing, saturated with hot water is kept in contact with the skin after the direct exposure has ended. The model takes data from a broad summary of the literature which examines the ranges of reported tissue thicknesses, tissue thermophysical properties, and blood perfusion. Water temperatures ranging from 60–90°C and total exposure durations up to 110 seconds were modeled. As expected, longer durations and elevated temperatures lead to a greater extent of tissue injury. Calculated values of tissue injury were compared with prior injury reports. These reports, taken from the literature, reinforce the present calculations. It is seen that numerical models can accurately predict burn injury as observed in clinical settings, in fact, the calculations of burn injury presented here provide more information for the appropriate treatment of burn injuries compared to visual observation.

scholarly journals Effects of calcium treatment on forest floor organic matter composition along an elevation gradient

2014 ◽  
Vol 44 (8) ◽  
pp. 969-976 ◽  
Author(s):  
Ankit Balaria ◽  
Chris E. Johnson ◽  
Peter M. Groffman
Keyword(s):  
Organic Matter ◽  
Chemical Change ◽  
Elevation Gradient ◽  
High Elevation ◽  
Hot Water ◽  
Long Term Effects ◽  
Organic Carbon Concentration ◽  
Significant Difference ◽  
Extractable Organic Matter ◽  
Water Extractable

Calcium amendment is a restorative option for nutrient-depleted, acidic soils in the forests of the northeastern United States. We studied the effects of watershed-scale wollastonite (CaSiO3) application on the structural composition of soil organic matter (SOM) and hot-water-extractable organic matter (HWEOM) at the Hubbard Brook Experiment Forest in New Hampshire 7–9 years after treatment, along an elevation gradient. Soils in the high-elevation spruce–fir–birch (SFB) zone contained significantly greater amounts of HWEOM compared with lower elevation hardwood soils, likely due to differences in litter quality and slower decomposition rates in colder soils at higher elevation. The only significant difference in hot-water-extractable organic carbon concentration between reference and calcium-treated watersheds was in Oie horizons of the SFB zone, which also exhibited the greatest degree of soil chemical change after treatment. The 13C nuclear magnetic resonance (NMR) spectra showed no significant patterns in O-alkyl C abundance for either soil or HWEOM along the elevation gradient, suggesting that there were no elevation-related patterns in carbohydrate concentration. The general absence of long-term effects in this study suggests that effects of Ca amendment at this dosage on the composition of SOM were small or short-lived.

scholarly journals A meteorological and blowing snow data set (2000–2016) from a high-elevation alpine site (Col du Lac Blanc, France, 2720 m a.s.l.)

2019 ◽  
Vol 11 (1) ◽  
pp. 57-69 ◽  
Author(s):  
Gilbert Guyomarc'h ◽  
Hervé Bellot ◽  
Vincent Vionnet ◽  
Florence Naaim-Bouvet ◽  
Yannick Déliot ◽  
...  
Keyword(s):  
Climate Models ◽  
Numerical Models ◽  
Winter Season ◽  
High Elevation ◽  
Mountain Range ◽  
Blowing Snow ◽  
Data Set ◽  
In Situ Data ◽  
Drifting Snow ◽  
Elevation Model

Abstract. A meteorological and blowing snow data set from the high-elevation experimental site of Col du Lac Blanc (2720 m a.s.l., Grandes Rousses mountain range, French Alps) is presented and detailed in this paper. Emphasis is placed on data relevant to the observations and modelling of wind-induced snow transport in alpine terrain. This process strongly influences the spatial distribution of snow cover in mountainous terrain with consequences for snowpack, hydrological and avalanche hazard forecasting. In situ data consist of wind (speed and direction), snow depth and air temperature measurements (recorded at four automatic weather stations), a database of blowing snow occurrence and measurements of blowing snow fluxes obtained from a vertical profile of snow particle counters (2010–2016). Observations span the period from 1 December to 31 March for each winter season from 2000–2001 to 2015–2016. The time resolution has varied from 15 min until 2014 to 10 min for the last years. Atmospheric data from the meteorological reanalysis are also provided from 1 August 2000 to 1 August 2016. A digital elevation model (DEM) of the study area (1.5 km2) at 1 m resolution is also provided in RGF 93 Lambert 93 coordinates. This data set has been used in the past to develop and evaluate physical parameterizations and numerical models of blowing and drifting snow in alpine terrain. Col du Lac Blanc is also a target site to evaluate meteorological and climate models in alpine terrain. It belongs to the CRYOBS-CLIM observatory (the CRYosphere, an OBServatory of the CLIMate), which is a part of the national research infrastructure OZCAR (Critical Zone Observatories – Application and Research) and have been a Global Cryospheric Watch Cryonet site since 2017. The data are available from the repository of the OSUG data centre https://doi.org/10.17178/CRYOBSCLIM.CLB.all.

scholarly journals Nunataks as barriers to ice flow: implications for palaeo ice-sheet reconstructions

2021 ◽  
Author(s):  
Martim Mas e Braga ◽  
Richard Selwyn Jones ◽  
Jennifer C. H. Newall ◽  
Irina Rogozhina ◽  
Jane L. Andersen ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Numerical Models ◽  
Ice Sheet ◽  
Direct Consequence ◽  
Surface Elevation ◽  
Ice Flow ◽  
Exposure Dating ◽  
Ice Surface ◽  
Topographic Relief

Abstract. Numerical models predict that discharge from the polar ice sheets will become the largest contributor to sea level rise over the coming centuries. However, the predicted amount of ice discharge and associated thinning depends on how well ice sheet models reproduce glaciological processes, such as ice flow in regions of large topographic relief, where ice flows around bedrock summits (i.e. nunataks) and through outlet glaciers. The ability of ice sheet models to capture long-term ice loss is best tested by comparing model simulations against geological data. A benchmark for such models is ice surface elevation change, which has been constrained empirically at nunataks and along margins of outlet glaciers using cosmogenic exposure dating. However, the usefulness of this approach in quantifying ice sheet thinning relies on how well such records represent changes in regional ice surface elevation. Here we examine how ice surface elevations respond to the presence of obstacles that create large topographic relief by modeling ice flow around and between idealised nunataks during periods of imposed ice sheet thinning. We found that, for realistic Antarctic conditions, a single nunatak could exert an impact on ice thickness over 20 km away from its summit, with its most prominent effect being a local increase (decrease) of the ice surface elevation of hundreds of metres upstream (downstream) of the obstacle. A direct consequence of this differential surface response for cosmogenic exposure dating was a delay in the time of bedrock exposure upstream relative to downstream of a nunatak. A nunatak elongated transverse to ice flow, with a wide subglacial continuation, was able to increase ice retention and therefore impose steeper ice surface gradients, while efficient ice drainage through outlet glaciers alleviated the differential response. Such differences, however, are not typically captured by continent-wide ice sheet models due to their coarse grid resolutions. This appears to be a key reason why models overestimate ice-sheet surface elevations and underestimate the pace of ice sheet melt contributing to sea level rise compared to empirical reconstructions. We conclude that a model grid refinement over complex topography and information about sample position relative to ice flow near the nunatak are necessary to improve data-model comparisons of ice surface elevation, and therefore the ability of models to simulate ice discharge in regions of large topographic relief.

scholarly journals Digital Mapping of the Nordaustlandet Ice Caps from Airborne Geophysical Investigations

1986 ◽  
Vol 8 ◽  
pp. 51-58 ◽  
Author(s):  
J.A. Dowdeswell ◽  
D.J. Drewry ◽  
A.P.R. Cooper ◽  
M.R. Gorman ◽  
O. Liestøl ◽  
...  
Keyword(s):  
Magnetic Energy ◽  
Direct Access ◽  
Ice Thickness ◽  
Ice Caps ◽  
Digital Mapping ◽  
Ice Surface ◽  
Radio Echo Sounding ◽  
Geophysical Investigations ◽  
Data Source ◽  
Electro Magnetic

Airborne geophysical investigations of the previously tittle-studied Nordaustlandet ice caps (11 150 km2) took place in 1983, using SPRI 60 MHz radio echo-sounding (RES) equipment of 160 dB system performance. RES and navigational data were recorded digitally. Navigation used a ranging system (accurate to ±30 m) from aircraft to ground-based transponders, located by satellite geoceivers, supplemented by the aircraft’s navigational instruments and timed crossings of known features. Ice surface and bedrock elevations were measured, using aircraft pressure altitude, terrain clearance, and ice thickness data. The mean error of 251 crossing points on Austfonna was 11 m. The reduced geophysical data are stored on a direct-access computer database. During 3400 km of flying, Austfonna (8105 km2) was covered by traverses a nominal 5 km apart, whereas a 15 km-spaced grid was flown over Vestfonna (2510 km2). Maps of ice surface morphology and subglacial, bedrock topography were produced for Austfonna and Vestfonna, along with an ice thickness map of Austfonna, Austfonna reaches a maximum surface elevation of 791 m and ice thickness of 583 m. 28% of the bedrock area beneath Austfonna lies below sea level. RES yielded bedrock echoes for 91% of track over Austfonna, but only 52% over Vestfonna. This was probably due to warmer conditions on Vestfonna, resulting in greater absorption and scattering of electro-magnetic energy. Ice surface elevations are a principal data source in the revision of official Norwegian maps of Nordaustlandet.

An Archive of Skin-Layer Thicknesses and Properties and Calculations of Scald Burns With Comparisons to Experimental Observations

2011 ◽  
Vol 3 (1) ◽  
Author(s):  
N. N. Johnson ◽  
J. P. Abraham ◽  
Z. I. Helgeson ◽  
W. J. Minkowycz ◽  
E. M. Sparrow
Keyword(s):  
Thermophysical Properties ◽  
Elevated Temperatures ◽  
Burn Injury ◽  
Tissue Injury ◽  
Numerical Models ◽  
Blood Perfusion ◽  
Skin Layer ◽  
Visual Observation ◽  
Hot Water ◽  
Direct Exposure

A numerical model has been constructed to assess the depth of injury incurred when skin is exposed to heated water. The model includes an extended duration that occurs when clothing, saturated with hot water, is kept in contact with the skin after the direct exposure has ended. The model takes data from a broad summary of literature, which examines the ranges of reported tissue thicknesses, tissue thermophysical properties, and blood perfusion. Water temperatures ranging from 60°C to 90°C and total exposure durations up to 110 s were modeled. As expected, longer durations and elevated temperatures lead to a greater extent of tissue injury. For lower values of temperatures (60°C), burns range from mild (0.1 mm) to severe (2.2 mm) depending on the exposure duration. On the other hand, for higher exposure temperatures (90°C), all durations led to burns that extended at least halfway through the dermal layer. As expected, burn depths with intermediate temperatures fell between these ranges. Calculated values of tissue injury were compared with prior injury reports. These reports, taken from literature, reinforce the present calculations. It is seen that numerical models can accurately predict burn injury as assessed by clinical observations; in fact, the calculations of burn injury presented here provide more information for the appropriate treatment of burn injuries compared with visual observation. Finally, literature values of a number of skin-layer thicknesses, thermophysical properties, and burn-injury parameters were collected and presented as an archival repository of information.

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