scholarly journals Evaluating the contribution of avalanching to the mass balance of Himalayan glaciers

2017 ◽  
Vol 58 (75pt2) ◽  
pp. 110-118 ◽  
Author(s):  
Sourav Laha ◽  
Reshama Kumari ◽  
Sunil Singh ◽  
Aditya Mishra ◽  
Tushar Sharma ◽  
...  
Keyword(s):  
Mass Balance ◽  
Control Experiment ◽  
Area Ratio ◽  
Model Description ◽  
Dominant Contribution ◽  
Himalayan Glaciers ◽  
Debris Cover ◽  
Term Variation ◽  
Accumulation Area Ratio

ABSTRACT Avalanching is a prominent source of accumulation on glaciers that have high and steep valley-walls surrounding their accumulation zones. These glaciers are typically characterised by an extensive supraglacial debris cover and a low accumulation area ratio. Despite an abundance of such glaciers in the rugged landscapes of the High Himalaya, attempts to quantify the net avalanche contribution to mass balance and its long-term variation are almost missing. We first discuss diagnostic criteria to identify strongly avalanche-fed glaciers. Second, we develop an approximate method to quantify the magnitude of the avalanche accumulation exploiting its expected control on the dynamics of these glaciers. The procedure is based on a simplified flowline model description of the glacier concerned and utilises the known glaciological mass-balance, velocity and surface-elevation profiles of the glacier. We apply the method to three Himalayan glaciers and show that the data on the recent dynamics of these glaciers are consistent with a dominant contribution of avalanches to the total accumulation. As a control experiment, we also simulate another Himalayan glacier where no significant avalanche contribution is expected, and reproduce the recent changes in that glacier without any additional avalanche contribution.

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.

scholarly journals Influence of debris cover on terminus retreat and mass changes of Chorabari Glacier, Garhwal region, central Himalaya, India

2013 ◽  
Vol 59 (217) ◽  
pp. 961-971 ◽  
Author(s):  
D.P. Dobhal ◽  
Manish Mehta ◽  
Deepak Srivastava
Keyword(s):  
Mass Balance ◽  
Climate Change Impacts ◽  
Ablation Rate ◽  
Background Information ◽  
Glacier Mass Balance ◽  
Mountain Range ◽  
Central Himalaya ◽  
Himalayan Glaciers ◽  
Debris Cover ◽  
Wide Variability

AbstractRecent studies of Himalayan glacier recession indicate that there is wide variability in terminus retreat rate and mass balance in the different sectors of the mountain range, primarily linked to the topography and climate of the region. Variable retreat rates of glacier termini and inadequate supporting field data (e.g. mass balance, ice thickness, velocity, etc.) in the Himalayan glaciers make it difficult to develop a coherent picture of climate change impacts. In this study, the results of a detailed mapping campaign and ground-based measurements of ablation rate, terminus retreat and ice loss are reported for the period 2003–10. In addition, background information from an old glacier map (Survey of India, 1962) was compiled and terminus recession measurements were carried out from 1990 field photographs of Chorabari Glacier, central Himalaya. Our ablation stake network results suggest that the influence of debris cover is significant for Chorabari Glacier mass balance and terminus retreat. The terminus survey finds that the glacier is retreating, but at a lower rate than many other non-debriscovered glaciers in the region. The recession and ablation data (particularly in the upper ablation area at higher altitudes) suggest that the ice volume loss of the glaciers is of greater magnitude than the slow terminus retreat and, if the process continues, the lowermost part of the glacier may reduce to a quasi-stationary position while significant ice loss continues.

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.

scholarly journals Mass balance of Himalayan glaciers using AAR and ELA methods

1992 ◽  
Vol 38 (128) ◽  
pp. 101-104 ◽  
Author(s):  
Anil V. Kulkarni
Keyword(s):  
Mass Balance ◽  
Correlation Coefficients ◽  
Western Himalaya ◽  
Positive Mass ◽  
Landsat Images ◽  
Equilibrium Line Altitude ◽  
Zero Mass ◽  
Himalayan Glaciers ◽  
Landsat Satellite ◽  
Accumulation Area Ratio

AbstractThe accumulation area ratio (AAR) for Himalayan glaciers representing zero mass balance is substantially lower than for North America and Europe. Regression analysis suggests 0.44 for the AAR representing zero mass balance in the western Himalaya. A good correlation was observed when this method was applied to individual glaciers such as Gara and Gor-Garang in Himachal Pradesh, India. The correlation coefficients (r), using 6 and 7 years of data, respectively, were 0.88 and 0.96 for Gara and Gor-Garang Glaciers, respectively. However, when data from six western Himalayan glaciers were correlated, the correlation was 0.74. The AAR was also estimated by using Landsat images which can be useful in obtaining a trend in mass balance for a large number of Himalayan glaciers for which very little information exists.A higher correlation was observed between equilibrium-line altitude (ELA) and mass balance. The field data from Gara and Gor-Garang Glaciers shows a high correlation coefficient, i.e. −0.92 and −0.94, respectively. The ELA values obtained from the Landsat satellite images combined with topographic maps suggest positive mass balance for the year 1986–87 and negative for 1987–88.

scholarly journals Forecasting temperate alpine glacier survival from accumulation zone observations

2010 ◽  
Vol 4 (1) ◽  
pp. 67-75 ◽  
Author(s):  
M. S. Pelto
Keyword(s):  
Mass Balance ◽  
Area Ratio ◽  
Surface Elevation ◽  
North Cascades ◽  
Rock Outcrops ◽  
Alpine Glacier ◽  
Accumulation Zone ◽  
The North ◽  
Cumulative Mass ◽  
Accumulation Area Ratio

Abstract. Temperate alpine glacier survival is dependent on the consistent presence of an accumulation zone. Frequent low accumulation area ratio values, below 30%, indicate the lack of a consistent accumulation zone, which leads to substantial thinning of the glacier in the accumulation zone. This thinning is often evident from substantial marginal recession, emergence of new rock outcrops and surface elevation decline in the accumulation zone. In the North Cascades 9 of the 12 examined glaciers exhibit characteristics of substantial accumulation zone thinning; marginal recession or emergent bedrock areas in the accumulation zone. The longitudinal profile thinning factor, f, which is a measure of the ratio of thinning in the accumulation zone to that at the terminus, is above 0.6 for all glaciers exhibiting accumulation zone thinning characteristics. The ratio of accumulation zone thinning to cumulative mass balance is above 0.5 for glacier experiencing substantial accumulation zone thinning. Without a consistent accumulation zone these glaciers are forecast not to survive the current climate or future additional warming. The results vary considerably with adjacent glaciers having a different survival forecast. This emphasizes the danger of extrapolating survival from one glacier to the next.

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 Mass balance of Himalayan glaciers using AAR and ELA methods

1992 ◽  
Vol 38 (128) ◽  
pp. 101-104 ◽  
Author(s):  
Anil V. Kulkarni
Keyword(s):  
Mass Balance ◽  
Correlation Coefficients ◽  
Western Himalaya ◽  
Positive Mass ◽  
Landsat Images ◽  
Equilibrium Line Altitude ◽  
Zero Mass ◽  
Himalayan Glaciers ◽  
Landsat Satellite ◽  
Accumulation Area Ratio

AbstractThe accumulation area ratio (AAR) for Himalayan glaciers representing zero mass balance is substantially lower than for North America and Europe. Regression analysis suggests 0.44 for the AAR representing zero mass balance in the western Himalaya. A good correlation was observed when this method was applied to individual glaciers such as Gara and Gor-Garang in Himachal Pradesh, India. The correlation coefficients (r), using 6 and 7 years of data, respectively, were 0.88 and 0.96 for Gara and Gor-Garang Glaciers, respectively. However, when data from six western Himalayan glaciers were correlated, the correlation was 0.74. The AAR was also estimated by using Landsat images which can be useful in obtaining a trend in mass balance for a large number of Himalayan glaciers for which very little information exists.A higher correlation was observed between equilibrium-line altitude (ELA) and mass balance. The field data from Gara and Gor-Garang Glaciers shows a high correlation coefficient, i.e. −0.92 and −0.94, respectively. The ELA values obtained from the Landsat satellite images combined with topographic maps suggest positive mass balance for the year 1986–87 and negative for 1987–88.

scholarly journals 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.

scholarly journals Estimating the avalanche contribution to the mass balance of debris covered glaciers

2014 ◽  
Vol 8 (1) ◽  
pp. 641-657 ◽  
Author(s):  
A. Banerjee ◽  
R. Shankar
Keyword(s):  
Steady State ◽  
Mass Balance ◽  
Western Himalaya ◽  
Area Ratio ◽  
Systematic Bias ◽  
Specific Mass ◽  
Model Estimate ◽  
High Head ◽  
Accumulation Area Ratio ◽  
The Himalaya

Abstract. Avalanche from high head walls dominates the net accumulation in many debris covered glaciers in the Himalaya. These avalanche contributions are difficult to directly measure and may cause a systematic bias in glaciological mass balance measurements. In this paper we develop a method to estimate the avalanche contribution using available data, within the context of an idealised flowline model of the glacier. We focus on Hamtah glacier in Western Himalaya and estimate the magnitude of the avalanche accumulation to its specific mass balance profile. Our estimate explains the reported discrepancy between values of recent glaciological and geodetic net mass balance for this glacier. Model estimate of accumulation area ratio (AAR) for this glacier is small (0.1) even at a steady state. This shows that empirical mass balance–AAR relationships derived from glaciers which do not have a significant avalanche contribution will not apply to a large region containing a significant fraction avalanche fed ones.

scholarly journals An Exigency for Ice Core Studies to Determine Spatio-temporal Variability in Moisture Sources and Impact of Black Carbon – Mineral Aerosols on the Himalayan Glaciers

2021 ◽  
Vol 4 (3) ◽  
Author(s):  
Sheikh Nawaz Ali ◽  
Anil D. Shukla
Keyword(s):  
Climate Change ◽  
Mass Balance ◽  
Water Resource Management ◽  
River Flow ◽  
Human Impacts ◽  
Current Trend ◽  
Glacier Mass Balance ◽  
Cascading Effects ◽  
Himalayan Glaciers

Himalayan glaciers‒ the store house of fresh water outside the polar region contributes ~45% of the total river flow by glacial melt in the Indus, Ganga and Brahmaputra watersheds which supports the livelihood of ~500 million people . The sustainability of these rivers is being questioned because of the growing evidences of accelerated glacier retreat in the recent decades, which is expected to have cascading effects on the mountainous areas and their surrounding lowlands. The rapid melting of Himalayan glaciers reveals their sensitivity to ongoing changes in climate dynamics, and if the current trend continues, rivers that rely heavily on snow/ice melt are expected to suffer hydrological disruptions to the point where some of the most populous areas may ‘run out of water’ during the dry season. Therefore, efforts are being made to study the glacier mass balance trends in order to understand the patterns and causes of recent recessional trend. Despite their importance, the absence of long-term mass-balance and remote sensing data restricts our knowledge of the Himalayan glaciers’ sensitivity/ response to climate change. Furthermore, such studies may be insufficient unless are compared to long-term glacier fluctuations (millennial and multi-millennial time scales), which aid in better understanding the natural trends of and human impacts on climate change, as well as assessing the causes and possible future of contemporary shrinking glaciers. This will also improve our understanding of past glacier behaviour in the context of primary causes of glacier change, which is critical for water resource management and understanding climate variability in high alpine areas where alternative proxy climate archives are typically scarce. Therefore, it is pertinent to pool our scientific resources and energy (i) towards understanding the Himalayan glaciers’ feeders (precipitation sources) and how they changed over time (geological and historical), as well as the causes of glaciers recession, one of which has been identified as (ii) black soot (carbon) in aerosol pollution.

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