On the Estimation of Antarctic Iceberg Melt Rate

Neshyba, Steve; Josberger, Edward G.

doi:10.1175/1520-0485(1980)010<1681:oteoai>2.0.co;2

Cited by 41 publications

(48 citation statements)

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“…In front of GPM, depth averaged temperature varies from 5.1 • C in CT and 4.8 • C in BR in October to 6.0 • C in CT and 5.4 • C in BR in December (Figure 9). According to the previously proposed equations by Weeks and Campbell (1973), Neshyba andJosberger (1980), andRussel-Head (1980), the observed seasonal temperature difference cause ∼10-30% changes in subaqueous melt rate.…”

Section: Seasonal Variation In the Ice-front Positionmentioning

confidence: 90%

“…Therefore, the water temperature variations have a potential to cause the frontal ablation rate variation by changing subaqueous melt rate. Subaqueous melting of icebergs in the ocean has been studied using laboratory experiments (Weeks and Campbell, 1973;Neshyba and Josberger, 1980;Russel-Head, 1980). These studies proposed equations for subaqueous melting by considering water temperature as the most important variable.…”

Section: Seasonal Variation In the Ice-front Positionmentioning

confidence: 99%

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Seasonal Variations in Ice-Front Position Controlled by Frontal Ablation at Glaciar Perito Moreno, the Southern Patagonia Icefield

et al. 2017

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The front position of calving glaciers is controlled by ice speed and frontal ablation which consists of the two processes of calving and subaqueous melting. However, the relative importance of these processes in frontal variation is difficult to assess and poorly understood, particularly for freshwater calving glaciers. To better understand the mechanism of seasonal variations involved in the ice front variations of freshwater calving glaciers, we measured front position, ice surface speed, air temperature, and proglacial lakewater temperature of Glaciar Perito Moreno in Patagonia. No substantial fluctuations in front position and ice speed occurred during the 15-year period studied (1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013), despite a warming trend in air temperature (0.059 • C a −1 ). Seasonal variations were observed both in the ice-front position (±50 m) and ice speed (±15%). The frontal ablation rate, computed from the frontal displacement rate and the ice speed, varied in a seasonal manner with an amplitude approximately five times greater than that in the ice speed. The frontal ablation correlated well with seasonal lakewater temperature variations (r = 0.96) rather than with air temperature (r = 0.86). Our findings indicate that the seasonal ice front variations of Glaciar Perito Moreno are primarily due to frontal ablation, which is controlled through subaqueous melting by the thermal conditions of the lake.

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Section: Seasonal Variation In the Ice-front Positionmentioning

confidence: 90%

Section: Seasonal Variation In the Ice-front Positionmentioning

confidence: 99%

Seasonal Variations in Ice-Front Position Controlled by Frontal Ablation at Glaciar Perito Moreno, the Southern Patagonia Icefield

et al. 2017

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“…Some previous studies (e.g. Budd and others, 1980;Neshyba and Josberger, 1980;Russell-Head, 1980) have estimated melt rates in the temperature range 0-28C to be $0.1 m d -1…”

Section: Current Speeds Residence Times and Dissolution Ratesmentioning

confidence: 96%

Antarctic iceberg distribution and dissolution from ship-based observations

Jacka

Giles

2007

J. Glaciol.

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ABSTRACT. The Australian Antarctic Program's iceberg dataset (from ship-based observations), including information from the austral summer seasons 1984/85 to 1999/2000, is examined and used to extend earlier studies. Using 'snapshots' of the iceberg population to provide an idea of the iceberg life cycle, the distribution of icebergs between 60 and 1508 8 E is discussed in terms of calving regions and ocean currents. Temporal changes are also examined. The discussion leads us to the point where we can define an area, bounded to the north by the maximum sea-ice limit and to the south by the Antarctic Divergence, in which icebergs are confined as they drift eastward. This allows estimation of total dissolution, in terms of iceberg numbers and volume, within 108 longitudinal sectors and, with knowledge of drift speeds, iceberg movement rates and freshwater input across the sector. Iceberg dissolution rates are found to be $0.03-0.05 m d -1 and the total mass contribution of fresh water to the ocean as the icebergs traverse our 308 of longitude study sector is $32 Gt. This amounts to a contribution equivalent to precipitation of $15.5 cm a -1 , accounting for $2% of the total iceberg discharge from the Antarctic ice sheet.

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“…8) is that melt is able to explain the disappearance of most icebergs in the 10-50 m category within the estimated 3.5 month time interval that it takes to travel a 10· sector of longitude. The melt rate is thus estimated from the time required to melt half of the mean dimension of the smallest category where the frequency dis- (980) and the assessment of Neshyba and Josberger (1980). Robe and others (1977), however, have photographed an Arctic iceberg (approximate dimensions 725 m x 300 m x 30 m) which showed a horizontal melt rate of approximately 1.5 m ,?-l for a. typical surface water temperature between +2 and +4 C. In summer, it is possible for the top 50 m to reach +2·C (Budd and others, 1980, fig.…”

Section: Note That This Representation Only Applies To Icebergs Grementioning

confidence: 99%

Antarctic Iceberg Distribution and Dissolution

Hamley¹,

Budd²

1986

J. Glaciol.

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ABSTRACT. Shipboard observations (in accordance withNorsk Polar-Institutt guidelines) from 6 years of Australian National Antarctic Research Expeditions (ANARE) voyages have provided data giving a detailed knowledge of iceberg sizes and concentrations in the Southern Ocean between long. 60 0 and 140 0 E. The resulting size-frequency distributions are examined in conjunction with a knowledge of water movement along known drift tracks in a selected stud), area (between lat. 59 0 and 64 oS., and long. 90 0 and 120 E.) to determine iceberg-dissolution rates. The "median life" (before breaking) of icebergs less than 1000 m in horizontal dimension is estimated to be 0.2 a, which is significantly lower than was previously thought. The mean melt rate is estimated to be 0.12 m d-1 , which agrees broadly with previous laboratory studies. The relative contributions of melt, calving, and breakage, plus the enhancement effect of roll-over, are examined in estimating the natural dissolution rate. Breakage appears to be the dominant mechanism for larger icebergs with melt and calving able to explain the disappearance of icebergs in the smallest categories only (within the mean "median-life" period). Examination of the historical records of Captain Cook indicates that iceberg concentrations, as well as the northerly extent in this region 200 years ago, were compatible with the present data.

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On the Estimation of Antarctic Iceberg Melt Rate

Cited by 41 publications

References 0 publications

Seasonal Variations in Ice-Front Position Controlled by Frontal Ablation at Glaciar Perito Moreno, the Southern Patagonia Icefield

Seasonal Variations in Ice-Front Position Controlled by Frontal Ablation at Glaciar Perito Moreno, the Southern Patagonia Icefield

Antarctic iceberg distribution and dissolution from ship-based observations

Antarctic Iceberg Distribution and Dissolution

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