Comparison between measured and theoretical temperature profiles of the Camp Century, Greenland, Borehole

Weertman, J.

doi:10.1029/jb073i008p02691

Cited by 93 publications

(69 citation statements)

References 10 publications

(5 reference statements)

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“…8). The basal water predictions near Camp Century are more surprising, since in the late 1960s basal temperatures were measured to be 11.8 degrees below the 495 PMP (Weertman, 1968;MacGregor et al, 2016). One possible explanation, which was recently invoked to explain the presence of a lake less than 10 km from South Pole (where the bed is frozen), is that the basal water is yet to reach thermal equilibrium (Beem et al, 2017).…”

Section: Basal Water Basal Thermal State and Temperaturementioning

confidence: 99%

A constraint upon the basal water distribution and basal thermal state of the Greenland Ice Sheet from radar bed-echoes

Jordan¹,

Williams²,

Schroeder³

et al. 2018

Preprint

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Abstract. There is widespread, but often indirect, evidence that a significant fraction of the bed beneath the Greenland Ice Sheet is thawed (at or above the pressure melting point for ice). This includes the beds of major outlet glaciers and their tributaries and a large area around the North-GRIP borehole in the ice-sheet interior. The ice-sheet scale distribution of basal water is, however, poorly constrained by existing observations. In principle, airborne radio-echo sounding (RES) en-5 ables the detection of basal water from bed-echo reflectivity, but unambiguous mapping is limited by uncertainty in signal attenuation. Here we introduce a new RES diagnostic for basal water that is associated with wet to dry transitions in bed material: bed-echo reflectivity variability. Importantly, this diagnostic is demonstrated to be attenuation-insensitive and the technique enables combined analysis of over a decade of Operation IceBridge survey data. 10The basal water predictions are compared with existing analyses for the basal thermal state (frozen and thawed beds) and geothermal heat flux. In addition to the outlet glaciers, we demonstrate widespread water storage in the northern and eastern interior. Notably, we observe a quasi-linear 'corridor' of basal water extending from NorthGRIP to Petermann glacier that spatially correlates with elevated heat flux predicted by a recent magnetic model. Finally, with a general aim to stim-15 ulate regional and process specific investigations, the basal water predictions are compared with bed topography, subglacial flow paths, and ice-sheet motion. The basal water distribution, and its relationship with the basal thermal state, provides a new constraint for numerical models. 1The Cryosphere Discuss., https://doi

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Section: Basal Water Basal Thermal State and Temperaturementioning

confidence: 99%

A constraint upon the basal water distribution and basal thermal state of the Greenland Ice Sheet from radar bed-echoes

Jordan¹,

Williams²,

Schroeder³

et al. 2018

Preprint

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“…Therefore its influence is normally much smaller than the (x-independent) geothermal heat and can be neglected or approximated by a function which does not depend on x. The horizontal gradient eTg/ex depends on dh/dx and da/dx; but Weertman's (1968) equation (6b) Local values : h = 2.500 km; hr = 2.250 km ; x = 125 km (Philberth, 1972[b]). …”

Section: Application Of the Two-dimensional Solutionmentioning

confidence: 99%

“…In the upper part of the ice sheet, v", is considered to be independent of y (Philberth, B., 1956;Haefeli, 1961;Weertman, 1968;Dansgaard and Johnsen, 1969[b]; Philberth,I972[b]), and oVx/ox can be written dvx/dx = vx'; 02VX/OX2 = d 2 v",/dx 2 = vx" . Using the continuity equation we can write OVy/oy = -vx'.…”

Section: General Solution For the Two-dimensional Casementioning

confidence: 99%

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On the temperature gradient in the upper part of cold ice sheets

Philberth¹,

Fédérer²

1974

J. Glaciol.

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ABSTRACT. The influence of the surface slope on the temperature profile in the upper part of a cold ice sheet can be described by a function which is independent of the geothermal heat and the heat of friction. This function is calculated for the two-dimensional and the axisymmetric cases. In the two-dimensional case its simplest form is proportional to the horizontal velocity and to the height above bedrock reduced by a constant; another form of this function is approximately proportional to the square of velocity and height. REsuME . Sur le gradient de temperature dans les couches supirieures des caloUes glaciaires froides. L'influence de l'inclinaison de la surface sur le profil de temperature dans la partie superieure d'une calotte glaciaire froide peut etre decrite par une fonction qui est independante des chaleurs geothermique et de friction . Cette fonction est calculee pour les cas bidimensionnel et axisymmetrique. Dans le cas bidimensionnel la forme la plus simple de cette fonction est proportionnelle a la vitesse horizon tale et a l'altitude sur le lit rocheux diminuee d' une consta nte; une autre forme est donnee qui est approximativement proportionnelle au carrc~ de ces deux facteurs. ZUSAMMENFASSUNG. Ober den Temperaturgradienten im oberen Teil von kalten Eisschilden. Der Einfluss derOberflachenneigung auf das Temperaturprofil im oberen Teil eines kalten Eisschildes liisst sich als Funktion beschreiben, die unabhangig ist von der Erd-und der Reibungswarme. Diese Funktion ist ftir den zweidimensionalen und ftir den rotationssymetrischen Fall angegeben. Im zweidimensionalen Fall ist ihre einfachste Form proportional der Horizontalgeschwindigkeit und der urn eine Konstante reduzierten Hohe tiber dem Felsboden; eine andere Form ist angenahert proportional dem Quadrat dieser beiden Grossen.

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“…Early studies concerning temperature distributions in ice sheets considered local vertical profiles, thereby neglecting horizontal advection (or variations in horizontal advection) and using simple prescribed distributions of dissipative heating. Examples of such studies are Robin (1955), Weertman (1968) and Lliboutry (1979).…”

Section: Introductionmentioning

confidence: 99%

The Heat Budget of the Ross Drainage Basin

Oerlemans

1987

Dynamics of the West Antarctic Ice Sheet

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Integration of the thermodynamic equation over an entire drainage basin yields a fairly simple expression for the steady-state heat balance. This stems from the fact that dissipative heating can be calculated directly from the release of gravitational energy. When mass balance, surface temperature and geothermal input are known, the mean ice temperature at the grounding line can be obtained as a residual.The procedure is applied to the drainage basin feeding the Ross Ice Shelf. The resulting mean outlet temperature is -16.2 oC. The heating rates making the balance turn out to be (in 0.0001 K/yr): dissipation 8.2, advective flux divergence -13.5 and geothermal heating 5.3. The method also reveals how the mean outlet temperature depends on mass balance, surface elevation, etc.

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Comparison between measured and theoretical temperature profiles of the Camp Century, Greenland, Borehole

Cited by 93 publications

References 10 publications

A constraint upon the basal water distribution and basal thermal state of the Greenland Ice Sheet from radar bed-echoes

A constraint upon the basal water distribution and basal thermal state of the Greenland Ice Sheet from radar bed-echoes

On the temperature gradient in the upper part of cold ice sheets

The Heat Budget of the Ross Drainage Basin

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