scholarly journals Detection of near-surface ice on Mars with electromagnetic techniques on board future surface vehicles

2003 ◽  
Vol 108 (E4) ◽  
Author(s):  
Michel Hamelin
Keyword(s):  
Near Surface ◽  
Surface Ice

scholarly journals Ground ice in the Northern Foothills, northern Victoria Land, Antarctica

2004 ◽  
Vol 39 ◽  
pp. 495-500 ◽  
Author(s):  
Mauro Guglielmin ◽  
Hugh M. French
Keyword(s):  
Oxygen Isotope ◽  
Ross Sea ◽  
Progress Report ◽  
Ground Ice ◽  
Lake Ice ◽  
Near Surface ◽  
Victoria Land ◽  
Different Types ◽  
Glacier Ice ◽  
Surface Ice

AbstractThis progress report classifies the different types of ground-ice bodies that occur in the Northern Foothills, northern Victoria Land, Antarctica. Oxygen isotope variations are presented, but interpretation is kept to a minimum pending further investigations. Surface ice, as distinct from moving glacier ice, occurs in the form of widespread buried (‘dead’) glacier ice lying beneath ablation (sublimation) till, together with perennial lake ice, snow banks and icing-blister ice.’Dry’ permafrost is uncommon, and interstitial ice is usually present at the base of the active layer and in the near-surface permafrost. This probably reflects the supply of moisture from the Ross Sea and limited sublimation under today’s climate. Intrusive ice occurs as layers within perennial lake-ice covers and gives rise to small icing blisters. Small ice wedges found beneath the furrows of high-centered polygons appear to agree with the model of sublimation-till development proposed by Marchant and others (2002).

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

2016 ◽  
Vol 62 (234) ◽  
pp. 714-724 ◽  
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.

Mass balance and near-surface ice temperature structure of Baishui Glacier No.1 in Mt. Yulong

2013 ◽  
Vol 23 (4) ◽  
pp. 668-678 ◽  
Author(s):  
Jiankuo Du ◽  
Yuanqing He ◽  
Shuang Li ◽  
Shijin Wang ◽  
Hewen Niu ◽  
...  
Keyword(s):  
Mass Balance ◽  
Temperature Structure ◽  
Near Surface ◽  
Surface Ice

scholarly journals Peering into lunar permanently shadowed regions with deep learning

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
V. T. Bickel ◽  
B. Moseley ◽  
I. Lopez-Francos ◽  
M. Shirley
Keyword(s):  
Target Selection ◽  
Mission Planning ◽  
Small Scale ◽  
Limited Information ◽  
The Moon ◽  
Near Surface ◽  
Water Ice ◽  
Surface Ice ◽  
Near Future ◽  
Geomorphological Features

AbstractThe lunar permanently shadowed regions (PSRs) are expected to host large quantities of water-ice, which are key for sustainable exploration of the Moon and beyond. In the near future, NASA and other entities plan to send rovers and humans to characterize water-ice within PSRs. However, there exists only limited information about the small-scale geomorphology and distribution of ice within PSRs because the orbital imagery captured to date lacks sufficient resolution and/or signal. In this paper, we develop and validate a new method of post-processing LRO NAC images of PSRs. We show that our method is able to reveal previously unseen geomorphological features such as boulders and craters down to 3 meters in size, whilst not finding evidence for surface frost or near-surface ice. Our post-processed images significantly facilitate the exploration of PSRs by reducing the uncertainty of target selection and traverse/mission planning.

scholarly journals Buckling rate and overhang development at a calving face

2003 ◽  
Vol 49 (167) ◽  
pp. 577-586 ◽  
Author(s):  
Brian Hanson ◽  
Roger Le B. Hooke
Keyword(s):  
Stress Field ◽  
Compressive Strain ◽  
Horizontal Velocity ◽  
Strain Rates ◽  
Current Field ◽  
Longitudinal Compression ◽  
Near Surface ◽  
Face Height ◽  
The Face ◽  
Surface Ice

AbstractUsing the finite-element we have modeled the stress field near the calving face of an idealized tidewater glacier under a variety of assumptions about submarine calving-face height, subaerial calving-face height, and ice rheology. These simulations all suggest that a speed maximum should be present at the calving face near the waterline. In experiments without crevassing, the decrease in horizontal velocity above this maximum culminates in a zone of longitudinal compression at the surface somewhat up-glacier from the face. This zone of compression appears to be a consequence of the non-linear rheology of ice. It disappears when a linear rheology is assumed. Explorations of the near-surface stress field indicate that when pervasive crevassing of the surface ice is accounted for in the simulations (by rheological softening), the zone of compressive strain rates does not develop. Variations in the pattern of horizontal velocity with glacier thickness support the contention that calving rates should increase with water depth at the calving face. In addition, the height of the subaerial calving face may have an importance that is not visible in current field data owing to the lack of variation in height of such faces in nature. Glaciers with lower calving faces may not have sufficient tensile stress to calve actively, while tensile stresses in simulated higher faces are sufficiently high that such faces will be unlikely to build in nature.

scholarly journals Processes influencing near-surface heat transfer in Greenland's ablation zone

2018 ◽  
Author(s):  
Benjamin H. Hills ◽  
Joel T. Harper ◽  
Toby W. Meierbachtol ◽  
Jesse V. Johnson ◽  
Neil F. Humphrey ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Air Temperature ◽  
Moving Boundary ◽  
Radiative Energy ◽  
Ablation Zone ◽  
Transient Heating ◽  
Near Surface ◽  
The Mean ◽  
Surface Ice ◽  
Mean Annual Air Temperature

Abstract. To assess the influence of various mechanisms of heat transfer on the near-surface ice of Greenland's ablation zone, we incorporate highly resolved measurements of ice temperature into thermal modeling experiments. Seven separate temperature strings were installed at three different field sites, each with between 17 and 32 sensors and extending up to 20 m below the surface. In one string, temperatures were measured every 30 minutes, and the record is continuous for more than three years. We use these measured ice temperatures to constrain modeling analyses focused on four isolated processes to assess the relative importance of each to the near-surface ice temperature: 1) the moving boundary of an ablating surface, 2) thermal insulation by snow, 3) radiative energy input, and 4) temperature gradients below the seasonally active near-surface layer. In addition to these four processes, transient heating events were observed in two of the temperature strings. Despite no observations of meltwater pathways to the subsurface, these heating events are likely the refreezing of liquid water below 5–10 m of cold ice. Together with subsurface refreezing, the five heat transfer mechanisms presented here account for measured differences of up to 3 °C between the ice temperature at the depth where annual temperature variability is dissipated and the mean annual air temperature. Thus, in Greenland's ablation zone, the mean annual air temperature cannot be used to predict the near-surface ice temperature, as is commonly assumed.

scholarly journals Thermal Regime of a Surge-Type Glacier

1976 ◽  
Vol 16 (74) ◽  
pp. 251-259
Author(s):  
Robert Bindschadler ◽  
William D. Harrison ◽  
Charles F. Raymond ◽  
Claude Gantet
Keyword(s):  
Surface Temperature ◽  
Thermal Regime ◽  
Good Evidence ◽  
Surface Velocity ◽  
Velocity Data ◽  
Near Surface ◽  
Accuracy Of Measurement ◽  
Internal Deformation ◽  
Surface Ice ◽  
Maximum Measurement

AbstractRecent measurements of near-surface temperature and surface velocity from the Variegated Glacier are presented. Temperature was measured with thermocouples at nine sites spaced along the length of the glacier. Maximum measurement depths ranged from 8 m in the lower ablation area to 20 m in the accumulation area. Accuracy of measurement was about 0.1 deg. By the end of summer the temperature at all measured sites and depths was not measurably different from zero, indicating that practically all of the near-surface ice of the glacier is temperate. The distribution of surface velocity along the length of the glacier shows distinct variations with time which cannot be explained by internal deformation in the glacier as influenced by changes in ice depth and slope. This indicates that the glacier is sliding over much of its length, which requires that the base of the glacier is temperate. Taken together, the near-surface temperature and velocity data provide good evidence that Variegated Glacier is temperate throughout and also indicate that the surge behavior of this glacier cannot be explained by thermal triggering.

Water Ice at Mid-Latitudes on Mars

2021 ◽  
Author(s):  
Frances E. G. Butcher
Keyword(s):  
Climate Changes ◽  
Planetary Science ◽  
Subsurface Water ◽  
Forthcoming Article ◽  
Neutron Spectrometer ◽  
Near Surface ◽  
Water Ice ◽  
Orbital Parameters ◽  
Imaging Science ◽  
Surface Ice

This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Planetary Science. Please check back later for the full article. Mars’ mid-latitudes (roughly 30–60° N and S) host voluminous deposits of water ice in the subsurface. At present, perennial water ice cannot exist at the surface in these regions. This is because, for a significant portion of the Martian year, surface temperatures exceed the sublimation point of water ice under Mars’ low atmospheric pressure. Therefore, any seasonal water-ice frost that accumulates in winter sublimates back into the atmosphere in spring. However, a centimeters-to-meters-thick covering of lithic material can inhibit sublimation sufficiently to allow perennial stability of ice in the subsurface. Perennial ice in Mars’ mid-latitudes exists as pore-ice and excess-ice lenses within the regolith, and as massive accumulations of buried, high-purity ice akin to debris-covered glaciers on Earth. The ice is thought to range in age from hundreds of thousands to many hundreds of millions of years old. Its emplacement and modification has been widely attributed to cyclical climate changes induced by variations in Mars’ orbital parameters (primarily its axial tilt). Water ice in Mars’ mid-latitudes is therefore of significant interest for reconstructing such climate changes. It could also provide an essential in situ supply of water for future human missions to Mars. It is possible to infer the presence of water ice in Mars’ subsurface without direct imaging of the ice itself. For example, the distribution of near-surface ice was mapped using Mars Odyssey Neutron Spectrometer detections to calculate the percentage of water-equivalent hydrogen in the upper 1 m of the regolith. Orbital images have revealed a great diversity of ice-related landforms which suggest flow, thermal cycling, sublimation, and disruption (e.g. by impact cratering) of subsurface ice. In some locations, orbital ground-penetrating radar observations have been used to confirm subsurface ice content in areas where its presence has been inferred from the geomorphology of the surface. Water ice in Mars’ mid-latitudes has also been imaged directly by landed and orbital missions. The Phoenix lander exposed water-ice lenses just centimeters beneath the surface, in trenches that it excavated at 68 °N latitude. Orbital images from the High Resolution Imaging Science Experiment (HiRISE) camera on board Mars Reconnaissance Orbiter revealed transient bright ice deposits exhumed by small, fresh impacts into mid-latitude terrains, and ~100 m-high scarps of water ice in exposures through debris-covered ice deposits. In all these cases, the exposed ice has been observed to lose mass by sublimation over time. This demonstrates the essential role of lithic cover in preserving subsurface water ice in Mars’ mid-latitudes.

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