scholarly journals Hypsometry and sensitivity of the mass balance to changes in equilibrium-line altitude: the case of the Southern Patagonia Icefield

2014 ◽  
Vol 60 (219) ◽  
pp. 14-28 ◽  
Author(s):  
Hernán De Angelis
Keyword(s):  
Mass Balance ◽  
Rate Sensitivity ◽  
Area Ratio ◽  
Area Fraction ◽  
Equilibrium Line ◽  
Equilibrium Line Altitude ◽  
First Order ◽  
Southern Patagonia ◽  
Accumulation Area Ratio ◽  
Balance Functions

AbstractWe study the relation between glacier hypsometry and sensitivity of mass-balance rate to changes in equilibrium-line altitude (ELA) to assess whether hypsometry can reliably be used to estimate the sensitivity of unmeasured glaciers to changes in ELA. We express the sensitivity of mass-balance rate to ELA, dḂ/ dELA, as a function of accumulation–area ratio (AAR), its derivative against altitude, dAAR/dELA, and mass-balance functions of ELA. We then apply the concept to 139 glaciers in the Southern Patagonia Icefield for which we derive hypsometry and AAR, and analyze the influence of hypsometry on their mass-balance rate sensitivity. We confirm that glaciers where the bulk of area is located above (below) the ELA are the least (most) sensitive. Glaciers with unimodal hypsometric curves where the peak of area fraction is around the present ELA, and glaciers with bi-or multimodal area distributions, with the ELA located approximately between the bulges, have intermediate sensitivities. We conclude that hypsometry can be used as a first-order estimator of mass-balance rate sensitivity to ELA change.

scholarly journals Contrasting glacier variations of Glaciar Perito Moreno and Glaciar Ameghino, Southern Patagonia Icefield

2015 ◽  
Vol 56 (70) ◽  
pp. 26-32 ◽  
Author(s):  
Masahiro Minowa ◽  
Shin Sugiyama ◽  
Daiki Sakakibara ◽  
Takanobu Sawagaki
Keyword(s):  
Mass Balance ◽  
Area Ratio ◽  
Elevation Change ◽  
Climate Conditions ◽  
Altitude Profile ◽  
The Past ◽  
Surface Elevation Change ◽  
Southern Patagonia ◽  
Accumulation Area Ratio ◽  
Strong Control

AbstractGlaciar Perito Moreno (GPM) and Glaciar Ameghino (GA), Southern Patagonia Icefield, are in contact in the accumulation area, but have shown contrasting frontal variations in the past few decades. To investigate recent changes of the two glaciers and processes controlling the different responses to similar climate conditions, we measured surface elevation change from 2000 to 2008 and terminus positions from 1999 to 2012 using several types of satellite data. GPM shows no significant changes in terminus position and 0.4 ± 0.3 m a–1 thickening over the period, whereas GA retreated 55 ± 2 m a–1 and thinned 2.6 ± 0.3 m a–1. Mass-balance measurements over the period 1999/2000 show that accumulation at GPM was ten times greater than that at GA, but ablation was only three times greater. The mass-balance–altitude profile is similar for the two glaciers; differences in the mass-balance distribution are caused by differences in the accumulation–area ratio (AAR). Our results suggest that the AAR and the calving flux exert strong control on the evolution of glaciers in the region.

Surface mass balance of Davies Dome and Whisky Glacier on James Ross Island, north-eastern Antarctic Peninsula, based on different volume-mass conversion approaches

2019 ◽  
Vol 9 (1) ◽  
pp. 1-12
Author(s):  
Zbyněk Engel ◽  
Filip Hrbáček ◽  
Kamil Láska ◽  
Daniel Nývlt ◽  
Zdeněk Stachoň
Keyword(s):  
Mass Balance ◽  
Mass Gain ◽  
Equilibrium Line ◽  
South Shetland Islands ◽  
Surface Mass Balance ◽  
Equilibrium Line Altitude ◽  
Surface Mass ◽  
Shetland Islands ◽  
James Ross Island ◽  
Accumulation Area Ratio

This study presents surface mass balance of two small glaciers on James Ross Island calculated using constant and zonally-variable conversion factors. The density of 500 and 900 kg·m–3 adopted for snow in the accumulation area and ice in the ablation area, respectively, provides lower mass balance values that better fit to the glaciological records from glaciers on Vega Island and South Shetland Islands. The difference between the cumulative surface mass balance values based on constant (1.23 ± 0.44 m w.e.) and zonally-variable density (0.57 ± 0.67 m w.e.) is higher for Whisky Glacier where a total mass gain was observed over the period 2009–2015. The cumulative surface mass balance values are 0.46 ± 0.36 and 0.11 ± 0.37 m w.e. for Davies Dome, which experienced lower mass gain over the same period. The conversion approach does not affect much the spatial distribution of surface mass balance on glaciers, equilibrium line altitude and accumulation-area ratio. The pattern of the surface mass balance is almost identical in the ablation zone and very similar in the accumulation zone, where the constant conversion factor yields higher surface mass balance values. The equilibrium line altitude and accumulation-area ratio determined for the investigated glaciers differ by less than 2m and 0.01, respectively. The annual changes of equilibrium line altitude and the mean values determined over the period 2009–2015 for Whisky Glacier (311 ± 16 m a.s.l.) and Davies Dome (393 ± 18 m a.s.l.) coincide with the values reported from Bahía del Diablo Glacier on Vega Island but differ from the glaciological records on South Shetland Islands.

scholarly journals Identification of snow ablation rate, ELA, AAR and net mass balance using transient snowline variations on two Arctic glaciers

2013 ◽  
Vol 59 (216) ◽  
pp. 649-659 ◽  
Author(s):  
Sebastian H. Mernild ◽  
Mauri Pelto ◽  
Jeppe K. Malmros ◽  
Jacob C. Yde ◽  
Niels T. Knudsen ◽  
...  
Keyword(s):  
Mass Balance ◽  
High Spatial Resolution ◽  
Landsat Imagery ◽  
Ablation Rate ◽  
Area Ratio ◽  
Direct Measure ◽  
Equilibrium Line Altitude ◽  
Southeast Alaska ◽  
Migration Rates ◽  
Accumulation Area Ratio

AbstractIdentification of the transient snowline (TSL) from high spatial resolution Landsat imagery on Lemon Creek Glacier (LCG), southeast Alaska, USA, and Mittivakkat Gletscher (MG), southeast Greenland, is used to determine snow ablation rates, the equilibrium-line altitude (ELA) and the accumulation-area ratio (AAR). The rate of rise of the TSL during the ablation season on a glacier where the balance gradient is known provides a measure of the snow ablation rate. On both LCG and MG, snow pits were completed in regions that the TSL subsequently transects. This further provides a direct measure of the snow ablation rates for a particular year. TSL observations from multiple dates during the ablation season from 1998 to 2011 at LCG and 1999 to 2012 at MG were used to explore the consistency of the TSL rise and snow ablation rate. On LCG and MG the satellite-derived mean TSL migration rates were 3.8 ± 0.6 and 9.4 ± 9.1 m d−1, respectively. The snow ablation rates were 0.028 ± 0.004 m w.e. d−1 for LCG and 0.051 ± 0.018 m w.e. d−1 for MG estimated by applying a TSL–mass-balance-gradient method, and 0.031 ± 0.004 and 0.047 ± 0.019 m w.e. d−1 by applying a snow-pit–satellite method, illustrating significant agreement between the two different approaches for both field sites. Also, satellite-derived ELA and AAR, and estimated net mass-balance (Ba) conditions were in agreement with observed ELA, AAR and Ba conditions for LCG and MG.

scholarly journals Retreat of Wurtenkees, European East Alps, since 1850

1997 ◽  
Vol 24 ◽  
pp. 102-105
Author(s):  
W. Schöner ◽  
I. Auer ◽  
R. Böhm ◽  
N. Hammer ◽  
T. Wiesinger
Keyword(s):  
Global Warming ◽  
Mass Balance ◽  
Air Temperature ◽  
Climatic Conditions ◽  
Area Ratio ◽  
Summer Season ◽  
Degree Days ◽  
Equilibrium Line Altitude ◽  
The Mean ◽  
Accumulation Area Ratio

The retreat of Wurtenkees, a glacier of about 1 km2 in the European East Alps, is described by measurement of frontal change, interpretation of maps and a computed mass-balance series. Since 1850, Wurtenkees has been one of the most strongly retreating glaciers in this region. Mass balance has been measured since 1982. Measured values of the accumulation area ratio and the equilibrium-line altitude as well as a degree-days model are used for the description of the activity conditions of the glacier. Under present climatic conditions Wurtenkees would need a lowering of the mean air temperature during the summer season of 1–1.5° C to return to a balanced mass budget. With predicted global warming, the glacier is likely to disappear early in the 21st century.

scholarly journals Testing the area–altitude balance ratio (AABR) and accumulation–area ratio (AAR) methods of calculating glacier equilibrium-line altitudes

2021 ◽  
pp. 1-12
Author(s):  
Rachel P. Oien ◽  
Brice R. Rea ◽  
Matteo Spagnolo ◽  
Iestyn D. Barr ◽  
Robert G. Bingham
Keyword(s):  
Time Series ◽  
Mass Balance ◽  
Area Ratio ◽  
Summer Temperature ◽  
Equilibrium Line ◽  
Field Observations ◽  
Median Difference ◽  
Accumulation Area Ratio

Abstract In this study, we compare equilibrium-line altitudes (ELAs) calculated using the area–altitude balance ratio (AABR) and the accumulation–area ratio (AAR) methods, with measured ELAs derived from direct field observations. We utilise a GIS toolbox to calculate the ELA for 64 extant glaciers by applying the AABR and AAR methods to DEMs and polygons of their geometry. The calculated ELAs (c-ELAs) are then compared to measured zero-net balance ELAs (znb-ELAs) obtained from mass-balance time series held by the WGMS for the same glaciers. The correlation between znb-ELAs and AABR (1.56)/AAR (0.58) c-ELAs is very strong, with an r2 = 0.99. The smallest median difference between znb-ELAs and c-ELAs (i.e. 65.5 m) is obtained when a globally representative AABR of 1.56 is used. When applied to palaeoglacier-climate applications, this difference translates to ~0.42°C, well within the uncertainty of palaeotemperature proxies used to determine mean summer temperature at the ELA. The more widely used mean AABR of 1.75 is shown to be statistically invalid due to the skewness of the dataset. On this basis, when calculating glacier ELAs, we recommend the use of a global AABR value of 1.56.

scholarly journals Altitudinal variations of temperature, equilibrium line altitude, and accumulation-area ratio in Upper Indus Basin

2016 ◽  
Vol 48 (1) ◽  
pp. 214-230 ◽  
Author(s):  
Biswajit Mukhopadhyay ◽  
Asif Khan
Keyword(s):  
Hydrological Modeling ◽  
Area Ratio ◽  
Temperature Data ◽  
Equilibrium Line ◽  
Indus Basin ◽  
Lapse Rate ◽  
Equilibrium Line Altitude ◽  
Upper Indus Basin ◽  
Temperature Equilibrium ◽  
Accumulation Area Ratio

Quantitative measures of adiabatic lapse rate, equilibrium line altitude (ELA), and accumulation-area ratio (AAR) are important to understand the hydrological processes and conduct hydrological modeling in a highly glaciated watershed. We present a detailed analysis of temperature data from 21 climatic stations, hypsometric analyses of glacier distributions, and a method to analyze ablation gradients and runoff curves concurrently to quantify these parameters for the watersheds of the Upper Indus Basin (UIB), with 15,062 km2 of glacierized area and an elevation range of 361–8,611 m. We show that the ELA varies considerably from one watershed to another, implying a highly variable upper elevation limit up to which melting of snows and glaciers takes place throughout the basin. This is in sharp contrast to the assertions made by previous researchers. We show that the ELA is as low as 4,840 m in Astore watershed and it is as high as 6,200 m in Shyok watershed. In accordance with the variation of ELA, the AAR also varies considerably from one watershed to another. It is as low as 0.10 in Gilgit and as high as 0.65 in Zanskar watersheds. We ascribe 15–20% uncertainty to these estimates of ELA and AAR in UIB.

scholarly journals Retreat of Wurtenkees, European East Alps, since 1850

1997 ◽  
Vol 24 ◽  
pp. 102-105 ◽  
Author(s):  
W. Schöner ◽  
I. Auer ◽  
R. Böhm ◽  
N. Hammer ◽  
T. Wiesinger
Keyword(s):  
Global Warming ◽  
Mass Balance ◽  
Air Temperature ◽  
Climatic Conditions ◽  
Area Ratio ◽  
Summer Season ◽  
Degree Days ◽  
Equilibrium Line Altitude ◽  
The Mean ◽  
Accumulation Area Ratio

The retreat of Wurtenkees, a glacier of about 1 km2 in the European East Alps, is described by measurement of frontal change, interpretation of maps and a computed mass-balance series. Since 1850, Wurtenkees has been one of the most strongly retreating glaciers in this region. Mass balance has been measured since 1982. Measured values of the accumulation area ratio and the equilibrium-line altitude as well as a degree-days model are used for the description of the activity conditions of the glacier. Under present climatic conditions Wurtenkees would need a lowering of the mean air temperature during the summer season of 1–1.5° C to return to a balanced mass budget. With predicted global warming, the glacier is likely to disappear early in the 21st century.

scholarly journals Equilibrium-Line Altitudes and Paleoenvironment in the Merchants Bay Area, Baffin Island, N.W.T., Canada

1985 ◽  
Vol 31 (109) ◽  
pp. 205-213 ◽  
Author(s):  
Fred F. Hawkins
Keyword(s):  
Area Ratio ◽  
Equilibrium Line ◽  
Storm Tracks ◽  
Lateral Moraine ◽  
Baffin Island ◽  
Statistical Comparison ◽  
Bay Area ◽  
The North ◽  
Simple Geometry ◽  
Accumulation Area Ratio

AbstractThe fiordlands south of Merchants Bay contain an extensive, well-preserved moraine record of a late Foxe advance of local valley glaciers. This has allowed accurate reconstruction of former glacier margins and computation of former equilibrium-line altitudes (ELAs) by a variety of methods. Statistical comparison of three methods (maximum lateral-moraine elevation, median elevation, and accumulation area ratio (AAR)) shows that different techniques can give different results for the same glaciers. Lateral moraines gave estimates that were too low, probably due to post-glacial erosion or to non-deposition. Median elevations and the AAR method produced statistically similar results but only for glaciers of simple geometry. The median-elevation method fails to take into account variations in valley morphology and glaciological parameters, and so is not reliable in all situations. The AAR method is supported by empirical evidence and is the best of the three methods for estimating former ELAs.Analysis of trend surfaces of present and late Foxe ELAs shows changes in elevation and orientation through time due to changing environmental factors. Present ELAs are strongly influenced by local factors, southerly storm tracks, and warm maritime conditions. Paleo-ELAs do not show this influence, suggesting that Davis Strait may have been ice-covered during the late Foxe stade and that storm tracks were from the north.

scholarly journals An estimate of glacier mass balance for the Chandra basin, western Himalaya, for the period 1984–2012

2017 ◽  
Vol 58 (75pt2) ◽  
pp. 99-109 ◽  
Author(s):  
Sayli Atul Tawde ◽  
Anil V. Kulkarni ◽  
Govindasamy Bala
Keyword(s):  
Mass Balance ◽  
Water Resource Management ◽  
Western Himalaya ◽  
Ratio Method ◽  
Glacier Mass Balance ◽  
Equilibrium Line Altitude ◽  
Temperature Index ◽  
Field Investigations ◽  
Basin Scale ◽  
Accumulation Area Ratio

ABSTRACTAn improved understanding of fresh water stored in the Himalaya is crucial for water resource management in South Asia and can be inferred from glacier mass-balance estimates. However, field investigations in the rugged Himalaya are limited to a few individual glaciers and short duration. Therefore, we have recently developed an approach that combines satellite-derived snowlines, a temperature-index melt model and the accumulation-area ratio method to estimate annual mass balance of glaciers at basin scale and for a long period. In this investigation, the mass balance of 146 glaciers in the Chandra basin, western Himalaya, is estimated from 1984 to 2012. We estimate the trend in equilibrium line altitude of the basin as +113 m decade−1and the mean mass balance as −0.61 ± 0.46 m w.e. a−1. Our basin-wide mass-balance estimates are in agreement with the geodetic method during 1999–2012. Sensitivity analysis suggests that a 20% increase in precipitation can offset changes in mass balance for a 1 °C temperature rise. A water loss of 18% of the total basin volume is estimated, and 67% for small and low-altitude glaciers during 1984–2012, indicating a looming water scarcity crisis for villages in this valley.

The Annual Balance of North Cascade Glaciers, Washington, U.S.A., Measured and Predicted Using An Activity-Index Method

1988 ◽  
Vol 34 (117) ◽  
pp. 194-199 ◽  
Author(s):  
Mauri S. Pelto
Keyword(s):  
Mass Balance ◽  
Activity Index ◽  
Prediction Method ◽  
Climatic Conditions ◽  
Area Ratio ◽  
Index Method ◽  
The North ◽  
Snow Line ◽  
Accumulation Area Ratio ◽  
Annual Balance

AbstractThe annual balance has been measured for ten North Cascade glaciers in 1983–84, 1984–85, 1985–86, and 1986–87 (1984, 1985, 1986, and 1987). Based on these data, an annual balance prediction method was designed and tested. Comparison of measured versus predicted annual balances indicates an accuracy of ±0.22–0.30 m. The method is based on annual measurement of the accumulation area ratio (AAR), and determination of the perennially constant activity index and area-altitude distribution on each glacier. The accumulation area ratio is determined from aerial and ground photographs at the end of the ablation season. The activity index is identified from observation of the rise of the snow line with time, compared to measured snow depths above the snow line. The AAR-activity index method was used to calculate the annual balance of 47 North Cascade glaciers in 1984, 1985, 1986, and 1987. The mean balance during the 4 year period was —0.33 m.From the mass-balance records, it is apparent that North Cascade glaciers can be divided into six climatic sensitivity groups. Each glacier type responds differently to specific climatic conditions. The mass-balance variation for glaciers of the same type is small.Since 1977, warmer, drier climatic conditions have prevailed in the North Cascades, resulting in the retreat of 42 of the 47 glaciers examined.

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