scholarly journals Mass balance of White Glacier, Axel Heiberg Island, N.W.T., Canada, 1960–91

1996 ◽  
Vol 42 (142) ◽  
pp. 548-563 ◽  
Author(s):  
J.Graham Cogley ◽  
W. P. Adams ◽  
M. A. Ecclestone ◽  
F. Jung-Rothenhäusler ◽  
C. S. L. Ommanney
Keyword(s):  
Mass Balance ◽  
Satellite Images ◽  
Equilibrium Line ◽  
Glacier Mass Balance ◽  
Equilibrium Line Altitude ◽  
Fold Reduction ◽  
Random Samples ◽  
Measurements Errors ◽  
Standard Techniques

AbstractWhite Glacier is a valley glacier at 79.5°N with an area of 38.7 km2. Its mass balance has been measured, over 32 years with a 3 year gap, by standard techniques using the stratigraphic system with a stake density of the order of one stake per km2. Errors in stake mass balance are about ±(200–250) mm, due largely to the local unrepresentativeness of measurements. Errors in the whole-glacier mass balanceBare of the same order as single-slake errors. However, the lag-1 autocorrelation in the time series ofBis effectively zero, so it consists of independent random samples, and the error in the long-term “balance normal”〈B〉is noticeably less.〈B〉is −100 ± 48 mm. The equilibrium-line altitude (ELA) averages 970 m. with a range of 470–1400 m. Mass balance is well correlated with ELA, but detailed modelling shows that the equilibrium line is undetectable on visible-band satellite images. A reduced network of a few stakes could give acceptable but less accurate estimates of the mass balance, as could estimates based on data from a weather station 120 km away. There is no evidence of a trend in the mass balance of White Glacier. To detect a climatologically plausible trend will require a ten-fold reduction of measurement error, a conclusion which may well apply to most estimates of mass balance based on similar stake densities.

scholarly journals Mass balance of White Glacier, Axel Heiberg Island, N.W.T., Canada, 1960–91

1996 ◽  
Vol 42 (142) ◽  
pp. 548-563 ◽  
Author(s):  
J.Graham Cogley ◽  
W. P. Adams ◽  
M. A. Ecclestone ◽  
F. Jung-Rothenhäusler ◽  
C. S. L. Ommanney
Keyword(s):  
Mass Balance ◽  
Satellite Images ◽  
Equilibrium Line ◽  
Glacier Mass Balance ◽  
Equilibrium Line Altitude ◽  
Fold Reduction ◽  
Random Samples ◽  
Measurements Errors ◽  
Standard Techniques

AbstractWhite Glacier is a valley glacier at 79.5°N with an area of 38.7 km2. Its mass balance has been measured, over 32 years with a 3 year gap, by standard techniques using the stratigraphic system with a stake density of the order of one stake per km2. Errors in stake mass balance are about ±(200–250) mm, due largely to the local unrepresentativeness of measurements. Errors in the whole-glacier mass balance B are of the same order as single-slake errors. However, the lag-1 autocorrelation in the time series of B is effectively zero, so it consists of independent random samples, and the error in the long-term “balance normal” 〈B〉 is noticeably less. 〈B〉 is −100 ± 48 mm. The equilibrium-line altitude (ELA) averages 970 m. with a range of 470–1400 m. Mass balance is well correlated with ELA, but detailed modelling shows that the equilibrium line is undetectable on visible-band satellite images. A reduced network of a few stakes could give acceptable but less accurate estimates of the mass balance, as could estimates based on data from a weather station 120 km away. There is no evidence of a trend in the mass balance of White Glacier. To detect a climatologically plausible trend will require a ten-fold reduction of measurement error, a conclusion which may well apply to most estimates of mass balance based on similar stake densities.

scholarly journals Modelled glacier equilibrium line altitudes during the mid-Holocene in the southern mid-latitudes

2015 ◽  
Vol 11 (2) ◽  
pp. 603-636 ◽  
Author(s):  
C. Bravo ◽  
M. Rojas ◽  
B. M. Anderson ◽  
A. N. Mackintosh ◽  
E. Sagredo ◽  
...  
Keyword(s):  
New Zealand ◽  
Mass Balance ◽  
Southern Hemisphere ◽  
Equilibrium Line ◽  
Balance Model ◽  
Glacier Mass Balance ◽  
Equilibrium Line Altitude ◽  
Climate Conditions ◽  
Precipitation Changes ◽  
Autumn And Winter

Abstract. Glacier behaviour during the mid-Holocene (MH, 6000 year BP) in the Southern Hemisphere provides observational data to constrain our understanding of the origin and propagation of palaeo-climatic signals. We examine the climatic forcing of glacier expansion in the MH by evaluating modelled glacier equilibrium line altitude (ELA) and climate conditions during the MH compared with pre-industrial time (PI, year 1750) in the mid latitudes of the Southern Hemisphere, specifically in Patagonia and the South Island of New Zealand. Climate conditions for the MH are obtained from PMIP2 models simulations, which in turn force a simple glacier mass balance model to simulate changes in equilibrium-line altitude during this period. Climate conditions during the MH show significantly (p ≤ 0.05) colder temperatures in summer, autumn and winter, and significantly (p ≤ 0.05) warmer temperatures in spring. These changes are a consequence of insolation differences between the two periods. Precipitation does not show significant changes, but exhibits a temporal pattern with less precipitation from August to September and more precipitation from October to April during the MH. In response to these climatic changes, glaciers in both analysed regions have an ELA that is 15–33 m lower than PI during the MH. The main causes of this difference are the colder temperature during the MH, reinforcing previous results that mid-latitude glaciers are more sensitive to temperature change compared to precipitation changes. Differences in temperature have a dual effect on mass balance. First, during summer and early autumn less energy is available for melting. Second in late autumn and winter, lower temperatures cause more precipitation to fall as snow rather than rain, resulting in more accumulation and higher surface albedo. For these reasons, we postulate that the modelled ELA changes, although small, may help to explain larger glacier extents observed in the mid Holocene in both South America and New Zealand.

scholarly journals Long-Term Glacier Mass-Balance Investigations in Svalbard, 1950–88

1990 ◽  
Vol 14 ◽  
pp. 102-106 ◽  
Author(s):  
Jon Ove Hagen ◽  
Olav Liestøl
Keyword(s):  
Mass Balance ◽  
Winter Precipitation ◽  
Summer Temperature ◽  
Glacier Mass Balance ◽  
Climatic Warming ◽  
Equilibrium Line Altitude ◽  
Stable Conditions ◽  
The Mean ◽  
One Year

Mass-balance investigations on glaciers in Svalbard at high latitudes (78°N) show that the ice masses have been steadily decreasing during the period 1950–88. Detailed annual observations have been carried out on Brøggerbreen since 1966 and Lovénbreen since 1967. The mean specific net balances are −0.46 and −0.37 m year−1 water equivalent respectively. Only one year had positive net balance in this period. The cumulative mass lost in the period is then more than 10% of the volume in 1967. Zero net balance would be obtained if the summer temperature was lowered about 1°C or if the winter precipitation increased about 50%. There is a strong correlation between the net mass balance and the height of the equilibrium-line altitude (ELA). Because of the high amount of superimposed ice (10–30% of winter balance) stake readings are necessary to find the ELA. There is no sign of climatic warming through increased melting. The trend analysis of the data from the last 20 years shows stable conditions with a slight increase of the winter balance. The net balance is then slightly increasing and thus less negative than 20 years ago.

Decadal altitudinal glacier mass balance for the Maipo and Santa basins of South America

2021 ◽  
Author(s):  
Florian von Ah ◽  
Evan Miles ◽  
Inés Dussaillant ◽  
Thomas E. Shaw ◽  
Peter Molnar ◽  
...  
Keyword(s):  
Water Supply ◽  
Mass Loss ◽  
Mass Balance ◽  
River Basin ◽  
High Elevation ◽  
Equilibrium Line ◽  
Glacier Mass Balance ◽  
Flux Divergence ◽  
Equilibrium Line Altitude ◽  
Large Populations

<p>Andean glaciers are an important part of the water cycle of high elevation catchments and supply fresh water to large populations downstreams, especially during dry periods. They are experiencing dramatic mass loss due to a warming climate, and their catchments are among the most vulnerable. However, relatively few glaciers are monitored systematically due to accessibility and cost, limiting our understanding of mass accumulation and ablation rates. In this study, we estimated the decadal altitudinal mass balance of glaciers in the Maipo River Basin in central Chile and the Rio Santa Basin in the Cordillera Blanca in Peru for the periods of 2000-2009 and 2009-2018. We accomplished this by 1) correcting current ice thickness estimates for recent thinning, 2) deriving glacier velocities from Landsat data using the Glacier Image Velocimetry (GIV) toolbox, and 3) modelling ice flux divergence using the continuity approach to correct observed glacier thinning for flow. We validated the altitudinally-resolved mass balance with the few available observational datasets, then determined each domain’s equilibrium line altitude, accumulation area ratio, and ablation balance ratio for each period, which identifies the portion of annual ablation that is compensated by accumulation.</p><p>Our results highlight the influence of the Chilean ‘Mega-drought’ (2010-present) on glacier health in the Maipo River Basin, causing a dramatic reduction in glacier mass balance (decrease of 0.5 m w.e. a-1) below 5000 m a.s.l., raising the regional equilibrium line altitude from 4210 m a.s.l. during 2000-2009 to 4470 m a.s.l. ± 15 m during 2009-2018, and lowering accumulation area ratios from 0.65 to 0.55. In contrast, the Santa Basin glaciers showed very similar altitudinal mass balance patterns for both decades, with equilibrium line altitudes at ~5100 m a.s.l. and accumulation area ratios of ~0.5, indicating a basin already out of balance prior to 2000. </p><p>Large populations rely on glaciers’ water supply in both basins and the two basins’ glaciers contrast in terms of water supply sustainability. In the Maipo Basin, glaciers experienced little mass change in the first period (ablation balance ratio of 1.01) and experienced only slightly unsustainable mass loss in the second period (ablation balance ratio of 0.9) despite the Megadrought. The ablation balance ratio for the Santa Basin was lower for both periods (0.75) indicating that these glaciers are moderately unhealthy despite their recent retreat, and water managers should expect further reductions in glacier water supply. Our results will help to constrain glacier models to understand the timing of glacier change for this data-sparse region.</p>

scholarly journals Can the snowline be used as an indicator of the equilibrium line and mass balance for glaciers in the outer tropics?

2012 ◽  
Vol 58 (212) ◽  
pp. 1027-1036 ◽  
Author(s):  
Antoine Rabatel ◽  
Ana Bermejo ◽  
Edwin Loarte ◽  
Alvaro Soruco ◽  
Jesus Gomez ◽  
...  
Keyword(s):  
Mass Balance ◽  
Field Data ◽  
Satellite Images ◽  
Dry Season ◽  
Equilibrium Line ◽  
Mountain Range ◽  
Relevant Parameter ◽  
Major Step ◽  
Equilibrium Line Altitude ◽  
Climate Conditions

AbstractBecause the glacier snowline is easy to identify on optical satellite images and because in certain conditions it can be used as an indicator of the equilibrium line, it may be a relevant parameter for the study of the relationships between climate and glaciers. Although several studies have shown that the snowline altitude (SLA) at the end of the hydrological year is a good indicator of the equilibrium-line altitude (ELA) for mid-latitude glaciers, such a relationship remains conjectural for tropical glaciers. Indeed, unlike in mid-latitudes, tropical climate conditions result in a distinct seasonality of accumulation/ablation processes. We examine this relationship using direct field ELA and mass-balance measurements made on Glaciar Zongo, Bolivia (~16° S), vand Glaciar Artesonraju, Peru (~9° S), and the SLA retrieved from satellite images acquired in the past two decades. We show that on glaciers in the outer tropics: (1) ablation is reduced during the dry season in austral winter (May-August), the SLA does not change much, and satellite images acquired between May and August could be used to compute the SLA; and (2) the highest SLA detected on a number of satellite images acquired during the dry season provides a good estimate of the annual ELA. However, as snowfall events can occur during the dry season, the SLA detected on satellite images tends to underestimate the ELA. Thus, we recommend validating the SLA computed from satellite images with field data collected on a benchmark glacier before measuring the SLA on other glaciers in the same mountain range for which no field data are available. This study is a major step towards extending the measurement of glacier parameters (ELA and mass balance) at the scale of a whole mountain range in the outer tropics to better document the relationships between climate and glaciers.

scholarly journals Using remote-sensing data to determine equilibrium-line altitude and mass-balance time series: validation on three French glaciers, 1994–2002

2005 ◽  
Vol 51 (175) ◽  
pp. 539-546 ◽  
Author(s):  
Antoine Rabatel ◽  
Jean-Pierre Dedieu ◽  
Christian Vincent
Keyword(s):  
Remote Sensing ◽  
Mass Balance ◽  
Regional Scale ◽  
Remote Sensing Data ◽  
Ground Level ◽  
Equilibrium Line ◽  
Glacier Mass Balance ◽  
Mountain Range ◽  
Equilibrium Line Altitude ◽  
Sensing Data

AbstractAlpine glaciers are very sensitive to climate fluctuations, and their mass balance can be used as an indicator of regional-scale climate change. Here, we present a method to calculate glacier mass balance using remote-sensing data. Snowline measurements from remotely sensed images recorded at the end of the hydrological year provide an effective proxy of the equilibrium line. Mass balance can be deduced from the equilibrium-line altitude (ELA) variations. Three well-documented glaciers in the French Alps, where the mass balance is measured at ground level with a stake network, were selected to assess the accuracy of the method over the 1994–2002 period (eight mass-balance cycles). Results obtained by ground measurements and remote sensing are compared and show excellent correlation (r2 > 0.89), both for the ELA and for the mass balance, indicating that the remote-sensing method can be applied to glaciers where no ground data exist, on the scale of a mountain range or a given climatic area. The main differences can be attributed to discrepancies between the dates of image acquisition and field measurements. Cloud cover and recent snowfalls constitute the main restrictions of the image-based method.

scholarly journals 25 years (1981–2005) of equilibrium-line altitude and mass-balance reconstruction on Glacier Blanc, French Alps, using remote-sensing methods and meteorological data

2008 ◽  
Vol 54 (185) ◽  
pp. 307-314 ◽  
Author(s):  
Antoine Rabatel ◽  
Jean-Pierre Dedieu ◽  
Emmanuel Thibert ◽  
Anne Letréguilly ◽  
Christian Vincent
Keyword(s):  
Remote Sensing ◽  
Mass Balance ◽  
Satellite Images ◽  
Meteorological Data ◽  
Equilibrium Line ◽  
Surface Mass Balance ◽  
Mass Balances ◽  
Equilibrium Line Altitude ◽  
Surface Mass ◽  
French Alps

AbstractAnnual equilibrium-line altitude (ELA) and surface mass balance of Glacier Blanc, Ecrins region, French Alps, were reconstructed from a 25 year time series of satellite images (1981–2005). The remote-sensing method used was based on identification of the snowline, which is easy to discern on optical satellite images taken at the end of the ablation season. In addition, surface mass balances at the ELA were reconstructed for the same period using meteorological data from three nearby weather stations. A comparison of the two types of series reveals a correlation of r > 0.67 at the 0.01 level of significance. Furthermore, the surface mass balances obtained from remote-sensing data are consistent with those obtained from field measurements on five other French glaciers (r = 0.76, p < 0.01). Also consistent for Glacier Blanc is the total mass loss (10.8 m w.e.) over the studied period. However, the surface mass balances obtained with the remote-sensing method show lower interannual variability. Given that the remote-sensing method is based on changes in the ELA, this difference probably results from the lower sensitivity of the surface mass balance to climate parameters at the ELA.

scholarly journals Long-Term Glacier Mass-Balance Investigations in Svalbard, 1950–88

1990 ◽  
Vol 14 ◽  
pp. 102-106 ◽  
Author(s):  
Jon Ove Hagen ◽  
Olav Liestøl
Keyword(s):  
Mass Balance ◽  
Winter Precipitation ◽  
Summer Temperature ◽  
Glacier Mass Balance ◽  
Climatic Warming ◽  
Equilibrium Line Altitude ◽  
Stable Conditions ◽  
The Mean ◽  
One Year

Mass-balance investigations on glaciers in Svalbard at high latitudes (78°N) show that the ice masses have been steadily decreasing during the period 1950–88. Detailed annual observations have been carried out on Brøggerbreen since 1966 and Lovénbreen since 1967. The mean specific net balances are −0.46 and −0.37 m year−1 water equivalent respectively. Only one year had positive net balance in this period. The cumulative mass lost in the period is then more than 10% of the volume in 1967. Zero net balance would be obtained if the summer temperature was lowered about 1°C or if the winter precipitation increased about 50%. There is a strong correlation between the net mass balance and the height of the equilibrium-line altitude (ELA). Because of the high amount of superimposed ice (10–30% of winter balance) stake readings are necessary to find the ELA. There is no sign of climatic warming through increased melting. The trend analysis of the data from the last 20 years shows stable conditions with a slight increase of the winter balance. The net balance is then slightly increasing and thus less negative than 20 years ago.

scholarly journals Multi-year analysis of distributed glacier mass balance modelling and equilibrium line altitude on King George Island, Antarctic Peninsula

2017 ◽  
Author(s):  
Ulrike Falk ◽  
Damián A. López ◽  
Adrián Silva-Busso
Keyword(s):  
Mass Balance ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Equilibrium Line ◽  
South Shetland Islands ◽  
Glacier Mass Balance ◽  
Equilibrium Line Altitude ◽  
Potter Cove ◽  
Shetland Islands ◽  
Ice Cap

Abstract. The South Shetland Islands are located at the northern tip of the Antarctic Peninsula (AP). This region was subject to strong warming trends in the atmospheric surface layer. Surface air temperature increased about 3 K in 50 years, concurrent with retreating glacier fronts, an increase in melt areas, ice surface lowering and rapid break-up and disintegration of ice shelves. The positive trend in surface air temperature has currently come to a halt. Observed surface air temperature lapse rates show a high variability during winter months (standard deviations up to −1 K/100 m), and a distinct spatial heterogeneity reflecting the impact of synoptic weather patterns. The increased mesocyclonic activity during the winter time over the past decades in the study area results in intensified advection of warm, moist air with high temperatures and rain, and leads to melt conditions on the ice cap, fixating surface air temperatures to the melting point. Its impact on winter accumulation results in the observed negative mass balance estimates. Six years of continuous glaciological measurements on mass balance stake transects as well as five years of climatological data time series are presented and a spatially distributed glacier energy balance melt model adapted and run based on these multi-year data sets. The glaciological surface mass balance model is generally in good agreement with observations, except for atmospheric conditions promoting snow drift by high wind speeds, turbulence-driven snow deposition and snow layer erosion by rain. No drift can be seen over the course of the 5-year model run period. The winter accumulation does not suffice to compensate for the high variability in summer ablation. The results are analysed to assess changes in melt water input to the coastal waters, specific glacier mass balance and the equilibrium line altitude. The Fourcade Glacier catchment drains into Potter cove, has an area of 23.6 km2 and is to 93.8 % glacierized. Annual discharge from Fourcade Glacier into Potter Cove is estimated to q = 25 &amp;pm; 6 hm3 per year with the standard deviation of 8% annotating the high interannual variability. The average equilibrium line altitude (ELA) calculated from own glaciological observations on Fourcade Glacier over the time period 2010 to 2015 amounts to ELA = 260 &amp;pm; 20 m. Published studies suggest rather stable conditions of slightly negative glacier mass balance until the mid 80's with an ELA of approx. 150 m. The calculated accumulation area ratio suggests dramatic changes in the future extent of the inland ice cap for the South Shetland Islands.

scholarly journals First in situ record of decadal glacier mass balance (2003–2014) from the Bhutan Himalaya

2016 ◽  
Vol 57 (71) ◽  
pp. 289-294 ◽  
Author(s):  
Phuntsho Tshering ◽  
Koji Fujita
Keyword(s):  
Mass Balance ◽  
Direct Method ◽  
Eastern Himalaya ◽  
Glacier Mass Balance ◽  
Differential Gps ◽  
Humid Climate ◽  
Equilibrium Line Altitude ◽  
The Past ◽  
Southeastern Tibet

AbstractThis study presents the first decadal mass-balance record of a small debris-free glacier in the Bhutan Himalaya, where few in situ measurements have been reported to date. Since 2003 we have measured the mass balance of Gangju La glacier, which covers an area of 0.3km2 and extends from 4900 to 5200ma.s.l., using both differential GPS surveys (geodetic method) and stake measurements (direct method). The observed mass balance ranged from –1.12 to –2.04mw.e. a–1 between 2003 and 2014. The glacier exhibited much greater mass loss than neighbouring glaciers in the eastern Himalaya and southeastern Tibet, which are expected to be sensitive to climate change due to the monsooninfluenced humid climate. Observed mass-balance profiles suggest that the equilibrium-line altitude has been higher than Gangju La glacier since 2003, implying that the entire glacier has experienced net ablation for at least the past decade.

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