scholarly journals Seasonally stable temperature gradients through supraglacial debris in the Everest region of Nepal, Central Himalaya

2020 ◽  
pp. 1-12
Author(s):  
Ann V. Rowan ◽  
Lindsey I. Nicholson ◽  
Duncan J. Quincey ◽  
Morgan J. Gibson ◽  
Tristram D.L. Irvine-Fynn ◽  
...  
Keyword(s):  
Mass Balance ◽  
Monsoon Season ◽  
Temperature Gradients ◽  
Glacier Mass Balance ◽  
Central Himalaya ◽  
Atmospheric Conditions ◽  
Near Surface ◽  
Ice Surface ◽  
Glacier Ablation ◽  
The Impact

Abstract Rock debris covers ~30% of glacier ablation areas in the Central Himalaya and modifies the impact of atmospheric conditions on mass balance. The thermal properties of supraglacial debris are diurnally variable but remain poorly constrained for monsoon-influenced glaciers over the timescale of the ablation season. We measured vertical debris profile temperatures at 12 sites on four glaciers in the Everest region with debris thickness ranging from 0.08 to 2.8 m. Typically, the length of the ice ablation season beneath supraglacial debris was 160 days (15 May to 22 October)—a month longer than the monsoon season. Debris temperature gradients were approximately linear (r2 > 0.83), measured as −40°C m–1 where debris was up to 0.1 m thick, −20°C m–1 for debris 0.1–0.5 m thick, and −4°C m–1 for debris greater than 0.5 m thick. Our results demonstrate that the influence of supraglacial debris on the temperature of the underlying ice surface, and therefore melt, is stable at a seasonal timescale and can be estimated from near-surface temperature. These results have the potential to greatly improve the representation of ablation in calculations of debris-covered glacier mass balance and projections of their response to climate change.

scholarly journals Near-surface internal melting: a substantial mass loss on Antarctic Dry Valley glaciers

2014 ◽  
Vol 60 (220) ◽  
pp. 361-374 ◽  
Author(s):  
Matthew J. Hoffman ◽  
Andrew G. Fountain ◽  
Glen E. Liston
Keyword(s):  
Meteorological Data ◽  
Primary Source ◽  
Balance Model ◽  
Weathering Crust ◽  
Field Observations ◽  
Dry Valleys ◽  
Near Surface ◽  
Ice Surface ◽  
Dry Valley ◽  
Glacier Ablation

AbstractThe McMurdo Dry Valleys, southern Victoria Land, East Antarctica, are a polar desert, and melt from glacial ice is the primary source of water to streams, lakes and associated ecosystems. Previous work found that to adequately model glacier ablation and subsurface ice temperatures with a surface energy-balance model required including the transmission of solar radiation into the ice. Here we investigate the contribution of subsurface melt to the mass balance of (and runoff from) Dry Valley glaciers by including a drainage process in the model and applying the model to three glacier sites using 13 years of hourly meteorological data. Model results for the smooth glacier surfaces common to many glaciers in the Dry Valleys showed that sublimation was typically the largest component of surface lowering, with rare episodes of surface melting, consistent with anecdotal field observations. Results also showed extensive internal melting 5–15 cm below the ice surface, the drainage of which accounted for ~50% of summer ablation. This is consistent with field observations of subsurface streams and formation of a weathering crust. We identify an annual cycle of weathering crust formation in summer and its removal during the 10 months of winter sublimation.

Validation of atmospheric reanalyses over the Weddell Sea, Antarctica, using observations from drifting buoys

2021 ◽  
Author(s):  
John King ◽  
Gareth Marshall ◽  
Steve Colwell ◽  
Clare Allen-Sader ◽  
Tony Phillips
Keyword(s):  
Sea Ice ◽  
Austral Summer ◽  
Longwave Radiation ◽  
Weddell Sea ◽  
Balance Model ◽  
Atmospheric Conditions ◽  
Snow Layer ◽  
Near Surface ◽  
The Impact ◽  
Drifting Buoys

<p> </p><p>Global atmospheric reanalyses are frequently used to drive ocean-ice models but few data are available to assess the quality of these products in the Antarctic sea ice zone. We utilise measurements from three drifting buoys that were deployed on sea ice in the southern Weddell Sea in the austral summer of 2016 to validate the representation of near-surface atmospheric conditions in the ERA-Interim and ERA5 reanalyses produced by the European Centre for Medium Range Weather Forecasts (ECMWF). The buoys carried sensors to measure atmospheric pressure, air temperature and humidity, wind speed and direction, and downwelling shortwave and longwave radiation. One buoy remained in coastal fast ice for most of 2016 while the other two drifted northward through the austral winter and exited the pack ice during the following austral summer. Comparison of buoy measurements with reanalysis data indicates that both reanalyses represent the surface pressure field in this region accurately. Reanalysis temperatures are, however, biased warm by around 2 °C in both products, with the largest biases seen at the lowest temperatures. We suggest that this bias is a result of the simplified representation of sea ice in the reanalyses, in particular the lack of an insulating snow layer on top of the ice. We use a simple surface energy balance model to investigate the impact of the reanalysis biases on sea ice thermodynamics.</p>

scholarly journals The impact of Saharan dust and black carbon on albedo and long-term glacier mass balance

2015 ◽  
Vol 9 (1) ◽  
pp. 1133-1175 ◽  
Author(s):  
J. Gabbi ◽  
M. Huss ◽  
A. Bauder ◽  
F. Cao ◽  
M. Schwikowski
Keyword(s):  
Mass Balance ◽  
Black Carbon ◽  
Mineral Dust ◽  
Ice Cores ◽  
Swiss Alps ◽  
Saharan Dust ◽  
Glacier Mass Balance ◽  
Mass Balances ◽  
The Impact

Abstract. Light-absorbing impurities in snow and ice control glacier melt as shortwave radiation represents the main component of the surface energy balance. Here, we investigate the long-term effect of snow impurities, i.e. Saharan dust and black carbon (BC), on albedo and glacier mass balance. The analysis was performed over the period 1914–2014 for two sites on Claridenfirn, Swiss Alps, where an outstanding 100 year record of seasonal mass balance measurements is available. Information on atmospheric deposition of mineral dust and BC over the last century was retrieved from two firn/ice cores of high-alpine sites. A combined mass balance and snow/firn layer model was employed to assess the dust/BC-albedo feedback. Compared to pure snow conditions, the presence of Saharan dust and BC lowered the mean annual albedo by 0.04–0.06 and increased melt by 15–19% on average depending on the location on the glacier. BC clearly dominated absorption which is about three times higher than that of mineral dust. The upper site has experienced mainly positive mass balances and impurity layers were continuously buried whereas at the lower site, surface albedo was more strongly influenced by re-exposure of dust-enriched layers due to frequent years with negative mass balances.

scholarly journals Sensitivity of mountain glacier mass balance to changes in bare-ice albedo

2017 ◽  
Vol 58 (75pt2) ◽  
pp. 119-129 ◽  
Author(s):  
Kathrin Naegeli ◽  
Matthias Huss
Keyword(s):  
Mass Balance ◽  
Balance Model ◽  
Glacier Mass Balance ◽  
Landsat 8 ◽  
Glacier Surface ◽  
Mountain Glacier ◽  
Albedo Feedback ◽  
In Situ Data ◽  
The Impact ◽  
Near Future

ABSTRACT Albedo is an important parameter in the energy balance of bare-ice surfaces and modulates glacier melt rates. The prolongation of the ablation period enforces the albedo feedback and highlights the need for profound knowledge on impacts of bare-ice albedo on glacier mass balance. In this study, we assess the mass balance sensitivity of 12 Swiss glaciers with abundant long-term in-situ data on changes in bare-ice albedo. We use pixel-based bare-ice albedo derived from Landsat 8. A distributed mass-balance model is applied to the period 1997–2016 and experiments are performed to assess the impact of albedo changes on glacier mass balance. Our results indicate that glacier-wide mass-balance sensitivities to changes in bare-ice albedo correlate strongly with mean annual mass balances (r 2 = 0.81). Large alpine glaciers react more sensitively to bare-ice albedo changes due to their ablation areas being situated at lower elevations. We find average sensitivities of glacier-wide mass balance of −0.14 m w.e. a−1 per 0.1 albedo decrease. Although this value is considerably smaller than sensitivity to air temperature change, we stress the importance of the enhanced albedo feedback that will be amplified due to atmospheric warming and a suspected darkening of glacier surface in the near future.

Forcings of mass-balance variability in Karakoram-Himalaya

2020 ◽  
Author(s):  
Pankaj Kumar ◽  
Vladimir A. Ryabchenko ◽  
Aaquib Javed ◽  
Dmitry V. Sein ◽  
Md. Farooq Azam
Keyword(s):  
Mass Balance ◽  
Large Scale ◽  
Climate Model ◽  
Model Simulation ◽  
Large Fraction ◽  
Water Security ◽  
Spatiotemporal Variability ◽  
Glacier Mass Balance ◽  
Russian Science ◽  
The Impact

<p>Glacier retreat is a key indicator of climate variability and change. Karakoram-Himalaya (KH) glaciers are the source of several perennial rivers protecting water security of a large fraction of the global population. The region is highly vulnerable to climate change impacts, hence the sensitivity of KH glaciers to regional microclimate, especially the impact of individual parameters forcing have been not quantified yet. The present study, using a coupled dynamical glacier-climate model simulation results, analyses the modelled interannual variability of mass-balance for the period 1989-2016. It is validated against available observations to quantify for the first time the sensitivity of the glaciers mass-balance to the individual forcing over KH. The snowfall variability emerges as the key factor, explaining ~60% of the variability of regional glacier mass balance. We provide insight into the recent divergent glacier response over the Karakoram Himalaya. The results underline the need for careful measurements and model representations of snowfall spatiotemporal variability, one of the HK's least-studied meteorological variables, to capture the large-scale, but region-specific, glacier changes at the third pole.</p><p> </p><p> </p><p> </p><p>Acknowledgement:</p><p>The work was supported by Indian project no. DST/INT/RUS/RSF/P-33/G, and the Russian Science Foundation (Project 19-47-02015).</p>

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 The response of glaciers to climatic persistence

2016 ◽  
Vol 62 (233) ◽  
pp. 440-450 ◽  
Author(s):  
GERARD H. ROE ◽  
MARCIA B. BAKER
Keyword(s):  
Mass Balance ◽  
Statistical Tests ◽  
Glacier Mass Balance ◽  
Climate Variables ◽  
Glacier Changes ◽  
Actual Degree ◽  
Glacier Length ◽  
Temporal Persistence ◽  
Random Fluctuations ◽  
The Impact

AbstractThe attribution of past glacier length fluctuations to changes in climate requires characterizing glacier mass-balance variability. Observational records, which are relatively short, are consistent with random fluctuations uncorrelated in time, plus an anthropogenic trend. However, longer records of other climate variables suggest that, in fact, there is a degree of temporal persistence associated with internal (i.e. unforced) climate variability, and that it varies with location and climate. Therefore, it is likely that persistence does exist for mass balance, but records are too short to confirm its presence, or establish its magnitude, with conventional statistical tests. Extending the previous work, we explore the impact of potential climatic persistence on glacier length fluctuations. We use a numerical model and a newly developed analytical model to establish that persistence, even of a degree so small as to be effectively undetectable in the longest mass-balance records, can significantly enhance the resulting glacier length fluctuations. This has a big impact on glacier-excursion probabilities: what was an extremely unlikely event (<1%) can become virtually certain (>99%), when persistence is incorporated. Since the actual degree of climatic persistence that applies to any given glacier is hard to establish, these results complicate the attribution of past glacier changes.

scholarly journals Preliminary results of mass-balance observations of Yala Glacier and analysis of temperature and precipitation gradients in Langtang Valley, Nepal

2014 ◽  
Vol 55 (66) ◽  
pp. 9-14 ◽  
Author(s):  
Prashant Baral ◽  
Rijan B. Kayastha ◽  
Walter W. Immerzeel ◽  
Niraj S. Pradhananga ◽  
Bikas C. Bhattarai ◽  
...  
Keyword(s):  
Climate Change ◽  
Mass Balance ◽  
Lapse Rate ◽  
Convective Precipitation ◽  
Glacier Mass Balance ◽  
Equilibrium Line Altitude ◽  
Temperature And Precipitation ◽  
Meteorological Observations ◽  
The Impact ◽  
Langtang Valley

AbstractMonitoring the glacier mass balance of summer-accumulation-type Himalayan glaciers is critical to not only assess the impact of climate change on the volume of such glaciers but also predict the downstream water availability and the global sea-level change in future. To better understand the change in meteorological parameters related to glacier mass balance and runoff in a glacierized basin and to assess the highly heterogeneous glacier responses to climate change in the Nepal Himalaya and nearby ranges, the Cryosphere Monitoring Project (CMP) carries out meteorological observations in Langtang Valley and mass-balance measurements on Yala Glacier, a debris-free glacier in the same valley. A negative annual mass balance of –0.89m w.e. and the rising equilibrium-line altitude of Yala Glacier indicate a continuation of a secular trend toward more negative mass balances. Lower temperature lapse rate during the monsoon, the effect of convective precipitation associated with mesoscale thermal circulation in the local precipitation and the occurrence of distinct diurnal cycles of temperature and precipitation at different stations in the valley are other conclusions of this comprehensive scientific study initiated by CMP which aims to yield multi-year glaciological, hydrological and meteorological observations in the glacierized Langtang River basin.

scholarly journals High-resolution interactive modelling of the mountain glacier–atmosphere interface: an application over the Karakoram

2013 ◽  
Vol 7 (1) ◽  
pp. 103-144 ◽  
Author(s):  
E. Collier ◽  
T. Mölg ◽  
F. Maussion ◽  
D. Scherer ◽  
C. Mayer ◽  
...  
Keyword(s):  
High Resolution ◽  
Mass Balance ◽  
Land Surface ◽  
Traditional Approach ◽  
Coupled Model ◽  
Glacier Mass Balance ◽  
Glacier Surface ◽  
Mountain Glacier ◽  
Near Surface ◽  
Basin Scale

Abstract. The traditional approach to simulations of alpine glacier mass balance (MB) has been one-way, or offline, thus precluding feedbacks from changing glacier surface conditions on the atmospheric forcing. In addition, alpine glaciers have been only simply, if at all, represented in atmospheric models to date. Here, we extend a recently presented, novel technique for simulating glacier–atmosphere interactions without the need for statistical downscaling, through the use of a coupled high-resolution mesoscale atmospheric and physically-based mass balance modelling system that includes glacier MB and energy balance feedbacks to the atmosphere. We compare the model results over the Karakoram region of the northwestern Himalaya with both remote sensing data and in situ glaciological and meteorological measurements for the ablation season of 2004. We find that interactive coupling has a localized but appreciable impact on the near-surface meteorological forcing data and that incorporation of MB processes improves the simulation of variables such as land surface temperature and snow albedo. Furthermore, including feedbacks from the MB model has a non-negligible effect on simulated mass balance, reducing modelled ablation, on average, by 0.1 m w.e. (−6.0%) to a total of −1.5 m w.e. between 25 June–31 August 2004. The interactively coupled model shows promise as a new, multi-scale tool for explicitly resolving atmospheric-MB processes of mountain glaciers at the basin scale.

scholarly journals What glaciers are telling us about Earth's changing climate

2014 ◽  
Vol 8 (4) ◽  
pp. 3475-3491
Author(s):  
W. Tangborn ◽  
M. Mosteller
Keyword(s):  
Climate Change ◽  
Mass Balance ◽  
Balance Model ◽  
Mountain Glaciers ◽  
Established Relationship ◽  
Representative Selection ◽  
Meteorological Observations ◽  
Glacier Ablation ◽  
The Impact ◽  
Selection Of

Abstract. A glacier monitoring system has been developed to systematically observe and document changes in the size and extent of a representative selection of the world's 160 000 mountain glaciers (entitled the PTAAGMB Project). Its purpose is to assess the impact of climate change on human societies by applying an established relationship between glacier ablation and global temperatures. Two sub-systems were developed to accomplish this goal: (1) a mass balance model that produces daily and annual glacier balances using routine meteorological observations, (2) a program that uses Google Maps to display satellite images of glaciers and the graphical results produced by the glacier balance model. The recently developed PTAA glacier balance model is described and applied to eight glaciers to produce detailed mass balance reports. Comparing annual balances produced by the model to traditional manual measurements for 50–60 years yields R2 values of 0.50–0.60. The model also reveals an unusual but statistically significant relationship between the average ablation of Wrangell Range glaciers and global temperatures that have been derived from temperature data at 7000 stations in the Northern Hemisphere. This glacier ablation/global temperature relationship provides the means to use worldwide ablation results to anticipate problems caused by climate change.

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