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Pronk, Jan Bouke, Tobias Bolch, Owen King, Bert Wouters i Douglas I. Benn. "Contrasting surface velocities between lake- and land-terminating glaciers in the Himalayan region". Cryosphere 15, nr 12 (10.12.2021): 5577–99. http://dx.doi.org/10.5194/tc-15-5577-2021.
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Abstract. Meltwater from Himalayan glaciers sustains the flow of rivers such as the Ganges and Brahmaputra on which over half a billion people depend for day-to-day needs. Upstream areas are likely to be affected substantially by climate change, and changes in the magnitude and timing of meltwater supply are expected to occur in coming decades. About 10 % of the Himalayan glacier population terminates into proglacial lakes, and such lake-terminating glaciers are known to exhibit higher-than-average total mass losses. However, relatively little is known about the mechanisms driving exacerbated ice loss from lake-terminating glaciers in the Himalaya. Here we examine a composite (2017–2019) glacier surface velocity dataset, derived from Sentinel 2 imagery, covering central and eastern Himalayan glaciers larger than 3 km2. We find that centre flow line velocities of lake-terminating glaciers (N = 70; umedian: 18.83 m yr−1; IQR – interquartile range – uncertainty estimate: 18.55–19.06 m yr−1) are on average more than double those of land-terminating glaciers (N = 249; umedian: 8.24 m yr−1; IQR uncertainty estimate: 8.17–8.35 m yr−1) and show substantially more heterogeneity than land-terminating glaciers around glacier termini. We attribute this large heterogeneity to the varying influence of lakes on glacier dynamics, resulting in differential rates of dynamic thinning, which causes about half of the lake-terminating glacier population to accelerate towards the glacier termini. Numerical ice-flow model experiments show that changes in the force balance at the glacier termini are likely to play a key role in accelerating the glacier flow at the front, with variations in basal friction only being of modest importance. The expansion of current glacial lakes and the formation of new meltwater bodies will influence the dynamics of an increasing number of Himalayan glaciers in the future, and these factors should be carefully considered in regional projections.
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Maurer, Joshua M., Summer B. Rupper i Joerg M. Schaefer. "Quantifying ice loss in the eastern Himalayas since 1974 using declassified spy satellite imagery". Cryosphere 10, nr 5 (23.09.2016): 2203–15. http://dx.doi.org/10.5194/tc-10-2203-2016.
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Abstract. Himalayan glaciers are important natural resources and climate indicators for densely populated regions in Asia. Remote sensing methods are vital for evaluating glacier response to changing climate over the vast and rugged Himalayan region, yet many platforms capable of glacier mass balance quantification are somewhat temporally limited due to typical glacier response times. We here rely on declassified spy satellite imagery and ASTER data to quantify surface lowering, ice volume change, and geodetic mass balance during 1974–2006 for glaciers in the eastern Himalayas, centered on the Bhutan–China border. The wide range of glacier types allows for the first mass balance comparison between clean, debris, and lake-terminating (calving) glaciers in the region. Measured glaciers show significant ice loss, with an estimated mean annual geodetic mass balance of −0.13 ± 0.06 m w.e. yr−1 (meters of water equivalent per year) for 10 clean-ice glaciers, −0.19 ± 0.11 m w.e. yr−1 for 5 debris-covered glaciers, −0.28 ± 0.10 m w.e. yr−1 for 6 calving glaciers, and −0.17 ± 0.05 m w.e. yr−1 for all glaciers combined. Contrasting hypsometries along with melt pond, ice cliff, and englacial conduit mechanisms result in statistically similar mass balance values for both clean-ice and debris-covered glacier groups. Calving glaciers comprise 18 % (66 km2) of the glacierized area yet have contributed 30 % (−0.7 km3) to the total ice volume loss, highlighting the growing relevance of proglacial lake formation and associated calving for the future ice mass budget of the Himalayas as the number and size of glacial lakes increase.
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P.C, Shakti, Dhiraj Pradhananga, Wenchao Ma i Pei Wang. "An Overview of Glaciers Distribution in the Nepal Himalaya". Hydro Nepal: Journal of Water, Energy and Environment 13 (12.03.2014): 20–27. http://dx.doi.org/10.3126/hn.v13i0.10034.
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Correction: On 7th September 2015, Pei Wang was included as an author on this paper. He was omitted from the paper by mistake. John W. Pomeroy was removed as an author of the paper but was included in the Acknowledgements of the paper (p.26)Abstract:Glaciers in the Himalayas are the important resource for fresh water. Continuous releases of the water from these glaciers make an important contribution to the drinking water, agriculture, and hydropower supply of densely populated regions in south and central Asia. Glaciers are not only a necessity for the survival of the people living in the low lying areas but also for their prosperity. Therefore, special attention should be given to detail research in the distribution of the glaciers in the Himalayan region and its surroundings. Physical parameters of glaciers area, length, depth, elevation profiles were analyzed based on the data provided by WGMS and NSIDC (1989), which was updated in 2012. Machhapuchhre, Thyangbo, Cho Oyu, Taweche, Setta, Tingbo and Kanchanjanga glaciers were found as the smallest glaciers in terms of area (<1km2), mean length (< 2km) and mean depth (40m) in the Nepal Himalaya. Langtang Ngojumba, Barun and Yalung glaciers were found as the largest glaciers in terms of area (>50km2). Large difference between start and end elevation point of glaciers of Khumbu, Ngojumba, Imja, Langtang indicates coverage area profiles are large and located in steep slopes of the Nepal Himalaya, which may result in linear erosions and avalanches. This paper also discusses about the Glacier Lake Outburst Flood (GLOF) in the Himalayan region.HYDRO NEPAL Journal of Water, Energy and EnvironmentIssue No. 13, July 2013Page:20-27 Uploaded date: 3/12/2014
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Laha, Sourav, Reshama Kumari, Sunil Singh, Aditya Mishra, Tushar Sharma, Argha Banerjee, Harish Chandra Nainwal i R. Shankar. "Evaluating the contribution of avalanching to the mass balance of Himalayan glaciers". Annals of Glaciology 58, nr 75pt2 (lipiec 2017): 110–18. http://dx.doi.org/10.1017/aog.2017.27.
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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.
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NG, KAH CHOON, SUI CHAI YAP i KIN MENG CHENG. "ASSESSMENT OF GLACIER MASS BALANCE IN THE HIMALAYAN-KARAKORAM REGION". Quantum Journal of Social Sciences and Humanities 3, nr 3 (28.08.2022): 60–71. http://dx.doi.org/10.55197/qjssh.v3i3.144.
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Mountain glaciers are susceptible to climate change. Most high-elevation glaciers, including the Himalayan glaciers, have been receding at an unprecedented rate in recent decades. Moreover, most mountain glaciers are found in the Himalayan areas, but field sampling and research efforts are limited due to logistical and financial constraints. From 1997 to 1999, just 6.8 km² of the 33,000 km² were examined in the Himalayan region. Previous studies indicated that Himalayan glaciers have been melting at an alarming rate over the past few decades. The objective of this paper is to review glacier changes, with an emphasis on mass balance changes in the Himalayan-Karakoram ranges, using 15 ISI journal articles published between 2008 and 2017. The acquired data on glacier mass balance was used to create a glacier mass balance change map for quantification using ArcGIS software and Landsat map as base map. The majority of the glaciers in the study area melted at various rates, with the most extensive glacier loss occurring in the west Himalayan highlands and the lowest occurring in the Karakoram region. Therefore, additional scientific research have to be conducted, and significant actions have to be taken at many different levels to prevent the continued loss of glaciers in this area.
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Venkatesh, T. N., A. V. Kulkarni i J. Srinivasan. "Relative effect of slope and equilibrium line altitude on the retreat of Himalayan glaciers". Cryosphere Discussions 5, nr 5 (4.10.2011): 2571–604. http://dx.doi.org/10.5194/tcd-5-2571-2011.
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Abstract. A majority of glaciers in the Himalayas have been retreating. In this paper, we show that there are two major factors which control the advance/retreat of the Himalayan glaciers. They are the slope of the glacier and changes in the equilibrium line altitude. While it is well known, that these factors are important, we propose a new way of combining them and use it to predict retreat. Our model has been applied to the movement of eight Himalayan glaciers during the past 25 years. The model explains why the Gangotri glacier is retreating while Zemu of nearly the same length is stationary, even though they are subject to similar environmental changes. The model has also been applied to a larger set of glaciers in the Parbati basin, for which retreat based on satellite data is available, though over a shorter time period.
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Venkatesh, T. N., A. V. Kulkarni i J. Srinivasan. "Relative effect of slope and equilibrium line altitude on the retreat of Himalayan glaciers". Cryosphere 6, nr 2 (15.03.2012): 301–11. http://dx.doi.org/10.5194/tc-6-301-2012.
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Abstract. It has been observed that a majority of glaciers in the Himalayas have been retreating. In this paper, we show that there are two major factors which control the advance/retreat of the Himalayan glaciers. They are the slope of the glacier and changes in the equilibrium line altitude. While it is well known, that these factors are important, we propose a new way of combining them and use it to predict retreat. The functional form of this model has been derived from numerical simulations using an ice-flow code. The model has been successfully applied to the movement of eight Himalayan glaciers during the past 25 years. It explains why the Gangotri glacier is retreating while Zemu of nearly the same length is stationary, even if they are subject to similar environmental changes. The model has also been applied to a larger set of glaciers in the Parbati basin, for which retreat based on satellite data is available, though over a shorter time period.
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Thayyen, R. J., i J. T. Gergan. "Role of glaciers in watershed hydrology: ''Himalayan catchment'' perspective". Cryosphere Discussions 3, nr 2 (15.07.2009): 443–76. http://dx.doi.org/10.5194/tcd-3-443-2009.
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Abstract. A large number of Himalayan glacier catchments are under the influence of humid climate with snowfall in winter (November–April) and South-West monsoon in summer (June–September) dominating the regional hydrology. Such catchments are defined as ''Himalayan catchment'', where the glacier melt water contributes to the river flow during the period of annual high flows produced by the monsoon. Other two major glacio-hydrological regimes of the Himalaya are winter snow dominated Alpine catchments of the Kashmir and Karakoram region and cold-arid regions of the Ladakh mountain range. Factors influencing the river flow variations in a ''Himalayan catchment'' were studied in a micro scale glacier catchment in the Garhwal Himalaya, covering an area of 77.8 km2. Discharge data generated from three hydrometric stations established at different altitudes of the Din Gad stream during the summer ablation period of 1998, 1999, 2000, 2001, 2003 and 2004. These data has been analysed along with winter/summer precipitation, temperature and mass balance data of the Dokriani glacier to study the role of the glacier and precipitation in determining the runoff variations along the stream continuum from the glacier snout to 2360 m a.s.l. Study shows that the inter-annual runoff variations in a ''Himalayan glacier catchment'' is directly linked with the precipitation rather than mass balance changes of the glacier. Study suggest that warming induced initial increase of glacier degraded runoff and subsequent decline is a glaciers mass balance response and cannot be translated as river flow response in a ''Himalayan catchment'' as suggested by the IPCC, 2007. Study also suggest that the glacier runoff critically influence the headwater river flows during the years of low summer discharge and proposes that the Himalayan catchment could experience higher river flows and positive glacier mass balance regime together in association with strong monsoon. This paper intended to highlight the importance of creating credible knowledge on the Himalayan cryospheric processes to develop a global outlook on river flow response to cryospheric change and locally sustainable water resources management strategies.
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Arora, Prachita, Sheikh Nawaz Ali i Anupam Sharma. "Role of Different Moisture Sources in Driving the Western Himalayan Past-glacier Advances". Journal of Atmospheric Science Research 6, nr 3 (25.05.2023): 1–19. http://dx.doi.org/10.30564/jasr.v6i3.5581.
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The fragmented pattern and the rapidly declining preservation of older glacial features/evidences limits the precision, with which glacial chronologies can be established. The challenge is exacerbated by the scarcity of datable material and limitations of dating methods. Nevertheless, the preserved glacial landforms have been fairly utilized to establish glacial chronologies from different sectors of the Indian Himalayas. The existing Himalayan glacial chrono-stratigraphies have revealed that in a single valley, past glacial advances rarely surpass four stages. Thus, local and regional glacial chronologies must be synthesized to understand glacial dynamics and potential forcing factors. This research presents an overview of glacier responses to climate variations revealed by glacial chrono-stratigraphies in the western Indian Himalayan region over the Quaternary (late). The synthesis demonstrated that, although the glacial advances were sporadic, glaciers in western Himalayas generally advanced during the Marine isotope stage (MIS)-3/4, MIS-2, late glacial, Younger Dryas (YD) and Holocene periods. The Holocene has witnessed multiple glacial advances and the scatter is significant. While previous glacial research revealed that Himalayan glaciers were out of phase with the global last glacial maximum (gLGM), weak Indian Summer Monsoon (ISM) has been implicated (ISM was reduced by roughly 20%). Recent research, however, has shown that gLGM glaciation responded to the global cooling associated with the enhanced mid-latitude westerlies (MLW). Further, the magnitude of gLGM glacier advance varied along and across the Himalayas particularly the transitional valleys located between the ISM and MLW influence. It is also evident that both the ISM and MLW have governed the late Quaternary glacial advances in the western Himalayan region. However, the responses of glaciers to ISM changes are more prominent. The insights gained from this synthesis will help us understand the dynamics of glacier response to climate change, which will be valuable for future climate modelling.
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Singh, Virendra Bahadur, AL Ramanathan i Pramod Kumar. "Hydro-meteorological Correlations of Himalayan Glaciers: A Review". Journal of Climate Change 7, nr 3 (2.09.2021): 45–55. http://dx.doi.org/10.3233/jcc210018.
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This review manuscript addresses hydro-meteorological correlations of various glaciers situated in the Himalayan region. Meteorological parameters influence the discharge pattern of the glacier. A strong correlation has been observed between discharge and air temperature of the studied Himalayan glaciers. Whereas, other meteorological parameters such as wind speed and wind direction etc. were not significantly correlated with the meltwater runoff of different glaciers in this region. In general, variability (Cv) in discharge from the various Himalayan glaciers such as Chhota Shigri and Gangotri glaciers follow the variability (Cv) in the temperature of these glaciers. Maximum variability (Cv) in meltwater runoff from the Chhota Shigri glacier has been reported in the month of September, which might be due to the fast decline in stream runoff and air temperature of the study area during the month of September. A strong relationship has been observed between suspended sediment concentration and temperature of the majority of studied Himalayan glaciers. Such type of result shows that the suspended sediment concentration in the glacial meltwater has increased with rising air temperature in this region.
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Banerjee, Argha. "Volume-area scaling for debris-covered glaciers". Journal of Glaciology 66, nr 259 (18.08.2020): 880–86. http://dx.doi.org/10.1017/jog.2020.69.
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AbstractA volume-area scaling relation is commonly used to estimate glacier volume or its future changes on a global scale. The presence of an insulating supraglacial debris cover alters the mass-balance profile of a glacier, potentially modifying the scaling relation. Here, the nature of scaling relations for extensively debris-covered glaciers is investigated. Theoretical arguments suggest that the volume-area scaling exponent for these glaciers is ~7% smaller than that for clean glaciers. This is consistent with the results from flowline-model simulations of idealised glaciers, and the available data from the Himalaya. The best-fit scale factor for debris-covered Himalayan glaciers is ~60% larger compared to that for the clean ones, implying a significantly larger stored ice volume in a debris-covered glacier compared to a clean one having the same area. These results may help improve scaling-based estimates of glacier volume and future glacier changes in regions where debris-covered glaciers are abundant.
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Alford, D., i R. Armstrong. "The role of glaciers in stream flow from the Nepal Himalaya". Cryosphere Discussions 4, nr 2 (1.04.2010): 469–94. http://dx.doi.org/10.5194/tcd-4-469-2010.
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Abstract. Recent concerns related to the potential impacts of the retreat of Himalayan glaciers on the hydrology of rivers originating in the catchment basins of the Himalaya have been accompanied by few analyses describing the role of glaciers in the hydrologic regime of these mountains. This is, at least in part, a result of the relative inaccessibility of the glaciers of the Himalaya, at altitudes generally between 4000–7000 m, and the extreme logistical difficulties of: 1) reaching the glaciers, and 2) conducting meaningful research once they have been reached. It is apparent that an alternative to traditional "Alpine" glaciology is required in the mountains of the Hindu Kush-Himalaya region. The objectives of the study discussed here have been to develop methodologies that will begin to quantify the role of complete glacier systems in the hydrologic regime of the Nepal Himalaya, and to develop estimates of the potential impact of a continued retreat of these glacier, based on the use of disaggregated low-altitude data bases, topography derived from satellite imagery, and simple process models of water and energy exchange in mountain regions. While the extent of mesoscale variability has not been established by studies to date, it is clear that the dominant control on the hydrologic regime of the tributaries to the Ganges Basin from the eastern Himalaya is the interaction between the summer monsoon and the 8000 m of topographic relief represented by the Himalayan wall. All the available evidence indicates that the gradient of specific runoff with altitude resulting from this interaction is moderately to strongly curvilinear, with maximum runoff occurring at mid-altitudes, and minima at the altitudinal extremes. At the upper minimum of this gradient, Himalayan glaciers exist in what has been characterized as an "arctic desert". The methodologies developed for this study involve the relationship between area-altitude distributions of catchment basins and glaciers, based on Shuttle Radar Topography Mission (SRTM3) data and water and energy exchange gradients. Based on these methodologies, it is estimated that the contribution of glacier annual melt water to annual stream flow into the Ganges Basin from the glacierized catchments of the Nepal Himalaya represents approximately 4% of the total annual stream flow volume of the rivers of Nepal, and thus, is a minor component of the annual flow of the Ganges River. The models developed for this study indicate that neither stream flow timing nor volume of the rivers flowing into the Ganges Basin from Nepal will be affected materially by a continued retreat of the glaciers of the Nepal Himalaya.
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Birajdar, F., G. Venkataraman, I. Bahuguna i H. Samant. "A Revised Glacier Inventory of Bhaga Basin Himachal Pradesh, India : Current Status and Recent Glacier Variations". ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences II-8 (27.11.2014): 37–43. http://dx.doi.org/10.5194/isprsannals-ii-8-37-2014.
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Himalayan glaciers show large uncertainty regarding their present and future state due to their sensitive reaction towards change in climatic condition. Himalayan glaciers are unique as they are located in tropical, high altitude regions, predominantly valley type and many are covered with debris. The great northern plains of India sustain on the perennial melt of glaciers meeting the water requirements of agriculture, industries, domestic sector even in the months of summer when large tracts of the country go dry. Therefore, it is important to monitor and assess the state of snow and glaciers and to know the sustainability of glaciers in view of changing global scenarios of climate and water security of the nation. Any information pertaining to Himalayan glaciers is normally difficult to be obtained by conventional means due to its harsh weather and rugged terrains. Due to the ecological diversity and geographical vividness, major part of the Indian Himalaya is largely un-investigated. Considering the fact that Himalayan glaciers are situated in a harsh environment, conventional techniques of their study is challenging and difficult both in terms of logistics and finances whereas the satellite remote sensing offers a potential mode for monitoring glaciers in long term. In order to gain an updated overview of the present state of the glacier cover and its changes since the previous inventories, an attempt has been made to generate a new remotesensing- derived glacier inventory on 1:50,000 scale for Bhaga basin (N32°28'19.7'' - N33°0'9.9'' ; E76°56'16.3'' - E77°25'23.7'' ) Western Himalaya covering an area of 1695.63 km2. having 231 glaciers and occupying glacierized area of 385.17 ±3.71 km2. ranging from 0.03 km<sup>2</sup>. to 29.28 km<sup>2</sup>. Glacier inventory has been carried out using high resolution IRS P6 LISS III data of 2011, ASTER DEM and other ancillary data. Specific measurements of mapped glacier features are the inputs for generating the glacier inventory data sheet with 37 parameters as per the UNESCO/TTS format, 11 additional parameters associated with the de-glaciated valley as per the suggestions of Space Application Center Ahmadabad and 9 newly introduced parameters of present study. The data sheet provides glacier wise details for each glacier on the significant glacier parameters like morphology, dimensions, orientation, elevation, etc. for both the active glacier component as well as the associated de-glaciated valley features. Assessment of recent variation in the glacierized area between 2001 and 2011. Results indicate that 231 glaciers covering an area of 391.56 ±3.76 km<sup>2</sup>. in 2001 has been reduced to 385.17 ±3.71 km<sup>2</sup>. in 2011; a loss of 1.63 ±1.0% in glacierized area within a period of 10 years. The present paper brings out the methodology adopted and salient results of the glacier inventory carried out which will help to enrich the existing database required for water resources assessment of the country and also meet the requirements of various researches working on climate change related studies.
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Banerjee, Argha, i R. Shankar. "On the response of Himalayan glaciers to climate change". Journal of Glaciology 59, nr 215 (2013): 480–90. http://dx.doi.org/10.3189/2013jog12j130.
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AbstractModelling the response of Himalayan glaciers to rapid climate change is an important problem. The poorly understood effects of debris cover and the variable response of the glaciers have made it difficult to understand their dynamics. We propose a simple model for debris-covered glaciers and validate it against data from Dokriani Glacier, India. Numerical investigations of the model show that the response of debris-covered glaciers to a warming climate has two timescales. There is a period when the glacier loses ice by thinning but the front is almost stationary and it develops a long, slow-flowing tongue. This stationary period, which can be >100 years for glaciers with a large extent of debris cover, is negligible for bare glaciers. The quasi-stagnant tongue does not develop in response to cooling. An analysis of remote-sensing data in the light of these results indicates that the variable response of the glaciers in the Himalaya is consistent with a climate that is warming on average, but has considerable spatial variability in the warming rates. We estimate the average warming rate to be about the same as the global average.
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AZAM, MOHD FAROOQ, PATRICK WAGNON, ETIENNE BERTHIER, CHRISTIAN VINCENT, KOJI FUJITA i JEFFREY S. KARGEL. "Review of the status and mass changes of Himalayan-Karakoram glaciers". Journal of Glaciology 64, nr 243 (9.01.2018): 61–74. http://dx.doi.org/10.1017/jog.2017.86.
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ABSTRACTWe present a comprehensive review of the status and changes in glacier length (since the 1850s), area and mass (since the 1960s) along the Himalayan-Karakoram (HK) region and their climate-change context. A quantitative reliability classification of the field-based mass-balance series is developed. Glaciological mass balances agree better with remotely sensed balances when we make an objective, systematic exclusion of likely flawed mass-balance series. The Himalayan mean glaciological mass budget was similar to the global average until 2000, and likely less negative after 2000. Mass wastage in the Himalaya resulted in increasing debris cover, the growth of glacial lakes and possibly decreasing ice velocities. Geodetic measurements indicate nearly balanced mass budgets for Karakoram glaciers since the 1970s, consistent with the unchanged extent of supraglacial debris-cover. Himalayan glaciers seem to be sensitive to precipitation partly through the albedo feedback on the short-wave radiation balance. Melt contributions from HK glaciers should increase until 2050 and then decrease, though a wide range of present-day area and volume estimates propagates large uncertainties in the future runoff. This review reflects an increasing understanding of HK glaciers and highlights the remaining challenges.
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Gul, Chaman, Shichang Kang, Siva Praveen Puppala, Xiaokang Wu, Cenlin He, Yangyang Xu, Inka Koch, Sher Muhammad, Rajesh Kumar i Getachew Dubache. "Measurement of light-absorbing particles in surface snow of central and western Himalayan glaciers: spatial variability, radiative impacts, and potential source regions". Atmospheric Chemistry and Physics 22, nr 13 (7.07.2022): 8725–37. http://dx.doi.org/10.5194/acp-22-8725-2022.
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Abstract. We collected surface snow samples from three different glaciers – Yala, Thana, and Sachin – in the central and western Himalayas to understand the spatial variability and radiative impacts of light-absorbing particles. The Yala and Thana glaciers in Nepal and Bhutan, respectively, were selected to represent the central Himalayas. The Sachin glacier in Pakistan was selected to represent the western Himalayas. The samples were collected during the pre- and post-monsoon seasons of the year 2016. The samples were analyzed for black carbon (BC) and water-insoluble organic carbon (OC) through the thermal optical method. The average mass concentrations (BC 2381 ng g−1; OC 3896 ng g−1; dust 101 µg g−1) in the western Himalayas (Sachin glacier) were quite high compared to the mass concentrations (BC 358 ng g−1, OC 904 ng g−1, dust 22 µg g−1) in the central Himalayas (Yala glacier). The difference in mass concentration may be due to the difference in elevation, snow age, local pollution sources, and meteorological conditions. BC in surface snow was also estimated through Weather Research and Forecasting (WRF) model coupled with Chemistry (WRF-Chem) simulations at the three glacier sites during the sampling periods. Simulations reasonably capture the spatial and seasonal patterns of the observed BC in snow but with a relatively smaller magnitude. Absolute snow albedo was estimated through the Snow, Ice, and Aerosol Radiative (SNICAR) model. The absolute snow albedo reduction ranged from 0.48 % (Thana glacier during September) to 24 % (Sachin glacier during May) due to BC and 0.13 % (Yala glacier during September) to 5 % (Sachin glacier during May) due to dust. The instantaneous radiative forcing due to BC and dust was estimated in the range of 0 to 96.48 and 0 to 25 W m−2, respectively. The lowest and highest albedo reduction and radiative forcing were observed in central and western Himalayan glaciers, respectively. The potential source regions of the deposited pollutants were inferred using WRF-Chem tagged-tracer simulations. Selected glaciers in the western Himalayas were mostly affected by long-range transport from the Middle East and central Asia; however, the central Himalayan glaciers were mainly affected by local and south Asia emissions (from Nepal, India, and China) especially during the pre-monsoon season. Overall, south Asia and west Asia were the main contributing source regions of pollutants.
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Shukla, Aparna, Siddhi Garg, Manish Mehta, Vinit Kumar i Uma Kant Shukla. "Temporal inventory of glaciers in the Suru sub-basin, western Himalaya: impacts of regional climate variability". Earth System Science Data 12, nr 2 (5.06.2020): 1245–65. http://dx.doi.org/10.5194/essd-12-1245-2020.
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Abstract. The importance of updated knowledge about the glacier extent and characteristics in the Himalaya cannot be overemphasized. Availability of precise glacier inventories in the latitudinally diverse western Himalayan region is particularly crucial. In this study we have created an inventory of the Suru sub-basin in the western Himalaya for the year 2017 using Landsat Operational Land Imager (OLI) data. Changes in glacier parameters have also been monitored from 1971 to 2017 using temporal satellite remote-sensing data and limited field observations. Inventory data show that the sub-basin has 252 glaciers covering 11 % of the basin, having an average slope of 25±6∘ (standard deviations have been italicized throughout the text) and dominantly north orientation. The average snow line altitude (SLA) of the basin is 5011±54 m a.s.l. with smaller (47 %) and cleaner (43 %) glaciers occupying the bulk area. Long-term climate data (1901–2017) show an increase in the mean annual temperature (Tmax and Tmin) of 0.77 ∘C (0.25 and 1.3 ∘C) in the sub-basin, driving the overall glacier variability in the region. Temporal analysis reveals a glacier shrinkage of ∼6±0.02 %, an average retreat rate of 4.3±1.02 m a−1, debris increase of 62 % and a 22±60 m SLA increase in the past 46 years. This confirms their transitional response between the Karakoram and the Greater Himalayan Range (GHR) glaciers. Besides, glaciers in the sub-basin occupy two major ranges, the GHR and Ladakh Range (LR), and experience local climate variability, with the GHR glaciers exhibiting a warmer and wetter climate as compared to the LR glaciers. This variability manifests itself in the varied response of GHR and LR glaciers. While the GHR glaciers exhibit an overall rise in SLA (GHR: 49±69 m; LR: decrease of 18±50 m), the LR glaciers have deglaciated more (LR: 7 %; GHR: 6 %) with an enhanced accumulation of debris cover (LR: 73 %; GHR: 59 %). Inferences from this study reveal prevalence of glacier disintegration and overall degeneration, transition of clean ice to partially debris-covered glaciers, local climate variability and non-climatic (topographic and morphometric)-factor-induced heterogeneity in glacier response as the major processes operating in this region. The Shukla et al. (2019) dataset is accessible at https://doi.org/10.1594/PANGAEA.904131.
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Adhikari, S., S. J. Marshall i P. Huybrechts. "A comparison of different methods of evaluating glacier response characteristics: application to glacier AX010, Nepal Himalaya". Cryosphere Discussions 3, nr 3 (17.09.2009): 765–804. http://dx.doi.org/10.5194/tcd-3-765-2009.
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Abstract. Himalayan glaciers are considered to be amongst the most sensitive glaciers to climate change. However, the response behaviour of these glaciers is not well understood. Here we use several approaches to estimate characteristic timescales of glacier AX010, a small valley glacier in the Nepal Himalaya, as a measure of glacier sensitivity. Assuming that temperature solely defines the mass budget, glacier AX010 waits for about 8 yr (reaction time) to exhibit its initial terminus response to changing climate. On the other hand, it takes between 29–56 yr (volume response time) and 37–70 yr (length response time) to adjust its volume and length following the changes in mass balance conditions, respectively. A numerical ice-flow model, the only method that yields both length and volume response time, confirms that a glacier takes longer to adjust its length than its volume.
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Bajracharya, S. R., S. B. Maharjan i F. Shrestha. "Understanding Dynamics of Himalayan Glaciers: Scope and Challenges of Remote Sensing". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-8 (28.11.2014): 1283–89. http://dx.doi.org/10.5194/isprsarchives-xl-8-1283-2014.
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remote-sensing based consistent semi-automated glacier mapping methodology with minimum manual intervention has been developed at ICIMOD. Using this methodology the glaciers of Hindu Kush Himalayan region were mapped in 2011 and continuously used for glacier mapping and monitoring in the region. These data were freely available to download from ICIMOD portal and GLIMS database. These comprehensive glacier information are the only data which is being used for research and development projects for countries like Bhutan, Nepal and Pakistan. Recently decadal glacier change from 1980 to 2010 of Nepal and Bhutan were published to understand the glacier change in the Himalaya. The decadal change assessment will be continued in other basins of HKH region to understand the glacier change. Due to rugged terrain, remote access, and logistic hindrance field verification is a challenging task and can be limited only in selected glaciers. Geodetic mass balance study in the selected glaciers like in Yala of Langtang basin and Rikha Samba of Hidden valley are on progress complement to field validation. High resolution images, lack of hydro-meteorological stations near to the glacier and limited competent manpower are another hindrance in the study of glacier change of the HKH region.
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Dobhal, D. P., Manish Mehta i Deepak Srivastava. "Influence of debris cover on terminus retreat and mass changes of Chorabari Glacier, Garhwal region, central Himalaya, India". Journal of Glaciology 59, nr 217 (2013): 961–71. http://dx.doi.org/10.3189/2013jog12j180.
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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.
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Rahul Singh, S., i Renu Dhir. "Change Monitoring of Burphu Glacier from 1963 to 2011 Using Remote Sensing". Asian Review of Civil Engineering 3, nr 1 (5.05.2014): 14–17. http://dx.doi.org/10.51983/tarce-2014.3.1.2203.
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Himalayas has one of the largest resources of snow and ice, which act as a freshwater reservoir for all the rivers originating from it. Monitoring of these resources is important for the assessment of availability of water in the Himalayan Rivers. The mapping of Glaciers is very difficult task because of the inaccessibility and remoteness of the terrain. Remote sensing techniques are often the only way to analyze glaciers in remote mountains and to monitor a large number of glaciers in multitemporal manner. This paper presents the results obtained from the analysis of a set of multitemporal Landsat MSS, TM and ETM+images for the monitoring and analysis of Burphu Glacier.
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Bisht, Kapil, Poonam Mehta, Shashi Upadhyay i Yogesh Joshi. "Need of Harnessing Potential of Lichenometry for Glacier Retreat Studies in the Indian Himalayan Region". INTERNATIONAL JOURNAL OF PLANT AND ENVIRONMENT 6, nr 03 (25.07.2020): 207–10. http://dx.doi.org/10.18811/ijpen.v6i03.08.
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In the present study an attempt has been made to attract the attention of the geologists, glaciologists and lichenologists of the world towards Himalaya. The Himalaya houses tremendous amount of eternal ice, and hence, is considered as the ‘Third Pole’ of earth. In the Asian Continent the Himalaya attains a very specific place and is considered as the ‘Water Tower’ of Asia. During recent decades the ice stored in the glaciers of Himalaya has shrunk considerably under the influence of global warming. Most of the Himalayan glaciers could not get desired field investigations due to their remoteness and unfavorable climate and are studied mostly through remote sensing based applications. In the present study, an attempt has been made to encourage the researchers to adapt lichenometry as a tool to investigate the retreat of Himalayan glaciers.
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Brun, F., M. Dumont, P. Wagnon, E. Berthier, M. F. Azam, J. M. Shea, P. Sirguey, A. Rabatel i Al Ramanathan. "Seasonal changes in surface albedo of Himalayan glaciers from MODIS data and links with the annual mass balance". Cryosphere Discussions 8, nr 3 (27.06.2014): 3437–74. http://dx.doi.org/10.5194/tcd-8-3437-2014.
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Abstract. Few glaciological field data are available on glaciers in the Hindu Kush – Karakoram – Himalaya (HKH) region, and remote sensing data are thus critical for glacier studies in this region. The main objectives of this study are to document, using satellite images, the seasonal changes of surface albedo for two Himalayan glaciers, Chhota Shigri Glacier (Himachal Pradesh, India) and Mera Glacier (Everest region, Nepal), and to reconstruct the annual mass balance of these glaciers based on the albedo data. Albedo is retrieved from MODerate Imaging Spectroradiometer (MODIS) images, and evaluated using ground based measurements. At both sites, we find high coefficients of determination between annual minimum albedo averaged over the glacier (AMAAG) and glacier-wide annual mass balance (Ba) measured with the glaciological method (R2 = 0.75). At Chhota Shigri Glacier, the relation between AMAAG found at the end of the ablation season and Ba suggests that AMAAG can be used as a proxy for the maximum snowline altitude or equilibrium line altitude (ELA) on winter accumulation-type glaciers in the Himalayas. However, for the summer-accumulation type Mera Glacier our approach relied on the hypothesis that ELA information, mostly not accessible from space during the monsoon, was still preserved later thanks to strong winter winds blowing away snow and in turn exposing again the late monsoon surface. AMAAG was subsequently revealed in the post-monsoon period. Reconstructed Ba at Chhota Shigri Glacier agrees with mass balances previously reconstructed using a positive degree-day method. Reconstructed Ba at Mera Glacier is affected by heavy cloud cover during the monsoon, which systematically limited our ability to observe AMAAG at the end of the melting period. In addition, the relation between AMAAG and Ba is constrained over a shorter time period for Mera Glacier (6 years) than for Chhota Shigri Glacier (11 years). Thus the mass balance reconstruction is less robust for Mera Glacier than for Chhota Shigri Glacier. However our method shows promising results and may be used to reconstruct the annual mass balance of glaciers with contrasted seasonal cycles in the western part of the HKH mountain range since the early 2000s when MODIS images became available.
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Sharma, Dinesh C. "Himalayan Glaciers Vanishing". Frontiers in Ecology and the Environment 2, nr 3 (kwiecień 2004): 118. http://dx.doi.org/10.2307/3868228.
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Kulkarni, Anil V. "Mass balance of Himalayan glaciers using AAR and ELA methods". Journal of Glaciology 38, nr 128 (1992): 101–4. http://dx.doi.org/10.1017/s0022143000009631.
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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.
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Kulkarni, Anil V. "Mass balance of Himalayan glaciers using AAR and ELA methods". Journal of Glaciology 38, nr 128 (1992): 101–4. http://dx.doi.org/10.3189/s0022143000009631.
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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.
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Takeuchi, Nozomu, Jun Uetake, Koji Fujita, Vladimir B. Aizen i Stanislav D. Nikitin. "A snow algal community on Akkem glacier in the Russian Altai mountains". Annals of Glaciology 43 (2006): 378–84. http://dx.doi.org/10.3189/172756406781812113.
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AbstractSnow algae are cold-tolerant algae growing on snow and ice and have been reported on glaciers in many parts of the world. Blooms of snow algae can reduce the surface albedo of snow and ice and significantly affect their melting. In addition, snow algae found in ice cores can be potential indicators of the paleo-environment, making them of great interest both to the biology and the geophysics of glaciers. A snow algal community was investigated in 2002 and 2003 on Akkem glacier in the Russian Altai mountains, where no information on its biological community has previously been available. Five species of snow algae including green algae and cyanobacteria were observed on the glacier. Red snow due to a bloom of algae (Chloromonas sp.) was visually apparent in the snow area during our study periods. The total algal cell-volume biomass on the glacier ranged from 97 to 1156μL m−2, which is equivalent to that reported previously on glaciers in the Himalaya and Alaska. The community structure showed that Mesotaenium berggrenii and/or Ancylonema nordenskioeldii, which are common species on glaciers in the Northern Hemisphere, were dominant in the ice area, while Chloromonas sp. was dominant in the snow area. Such community structures are similar to those on Alaskan and Arctic glaciers but differ from those on Himalayan and Tibetan glaciers, even though the Altai mountains are geographically closer to the Himalaya and Tibet than to Alaska. The difference in algal communities between the Altaic and other glaciers is discussed together with physical and chemical conditions affecting the algae.
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Brun, F., M. Dumont, P. Wagnon, E. Berthier, M. F. Azam, J. M. Shea, P. Sirguey, A. Rabatel i Al Ramanathan. "Seasonal changes in surface albedo of Himalayan glaciers from MODIS data and links with the annual mass balance". Cryosphere 9, nr 1 (13.02.2015): 341–55. http://dx.doi.org/10.5194/tc-9-341-2015.
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Abstract. Few glaciological field data are available on glaciers in the Hindu Kush–Karakoram–Himalayan (HKH) region, and remote sensing data are thus critical for glacier studies in this region. The main objectives of this study are to document, using satellite images, the seasonal changes of surface albedo for two Himalayan glaciers, Chhota Shigri Glacier (Himachal Pradesh, India) and Mera Glacier (Everest region, Nepal), and to reconstruct the annual mass balance of these glaciers based on the albedo data. Albedo is retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS) images, and evaluated using ground based measurements. At both sites, we find high coefficients of determination between annual minimum albedo averaged over the glacier (AMAAG) and glacier-wide annual mass balance (Ba) measured with the glaciological method (R2 = 0.75). At Chhota Shigri Glacier, the relation between AMAAG found at the end of the ablation season and Ba suggests that AMAAG can be used as a proxy for the maximum snow line altitude or equilibrium line altitude (ELA) on winter-accumulation-type glaciers in the Himalayas. However, for the summer-accumulation-type Mera Glacier, our approach relied on the hypothesis that ELA information is preserved during the monsoon. At Mera Glacier, cloud obscuration and snow accumulation limits the detection of albedo during the monsoon, but snow redistribution and sublimation in the post-monsoon period allows for the calculation of AMAAG. Reconstructed Ba at Chhota Shigri Glacier agrees with mass balances previously reconstructed using a positive degree-day method. Reconstructed Ba at Mera Glacier is affected by heavy cloud cover during the monsoon, which systematically limited our ability to observe AMAAG at the end of the melting period. In addition, the relation between AMAAG and Ba is constrained over a shorter time period for Mera Glacier (6 years) than for Chhota Shigri Glacier (11 years). Thus the mass balance reconstruction is less robust for Mera Glacier than for Chhota Shigri Glacier. However our method shows promising results and may be used to reconstruct the annual mass balance of glaciers with contrasted seasonal cycles in the western part of the HKH mountain range since the early 2000s when MODIS images became available.
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Thayyen, R. J., i J. T. Gergan. "Role of glaciers in watershed hydrology: a preliminary study of a "Himalayan catchment"". Cryosphere 4, nr 1 (9.02.2010): 115–28. http://dx.doi.org/10.5194/tc-4-115-2010.
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Abstract. A large number of Himalayan glacier catchments are under the influence of humid climate with snowfall in winter (November–April) and south-west monsoon in summer (June–September) dominating the regional hydrology. Such catchments are defined as "Himalayan catchment", where the glacier meltwater contributes to the river flow during the period of annual high flows produced by the monsoon. The winter snow dominated Alpine catchments of the Kashmir and Karakoram region and cold-arid regions of the Ladakh mountain range are the other major glacio-hydrological regimes identified in the region. Factors influencing the river flow variations in a "Himalayan catchment" were studied in a micro-scale glacier catchment in the Garhwal Himalaya, covering an area of 77.8 km2. Three hydrometric stations were established at different altitudes along the Din Gad stream and discharge was monitored during the summer ablation period from 1998 to 2004, with an exception in 2002. These data have been analysed along with winter/summer precipitation, temperature and mass balance data of the Dokriani glacier to study the role of glacier and precipitation in determining runoff variations along the stream continuum from the glacier snout to 2360 m a.s.l. The study shows that the inter-annual runoff variation in a "Himalayan catchment" is linked with precipitation rather than mass balance changes of the glacier. This study also indicates that the warming induced an initial increase of glacier runoff and subsequent decline as suggested by the IPCC (2007) is restricted to the glacier degradation-derived component in a precipitation dominant Himalayan catchment and cannot be translated as river flow response. The preliminary assessment suggests that the "Himalayan catchment" could experience higher river flows and positive glacier mass balance regime together in association with strong monsoon. The important role of glaciers in this precipitation dominant system is to augment stream runoff during the years of low summer discharge. This paper intends to highlight the importance of creating credible knowledge on the Himalayan cryospheric processes to develop a more representative global view on river flow response to cryospheric changes and locally sustainable water resources management strategies.
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Rawal, D., A. K. Sharma, A. Vyas i A. S. Rajawat. "DEVELOPMENT OF WEB BASED HIMALAYAN GLACIER INFORMATION SYSTEM USING OPEN SOURCE". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W8 (11.07.2018): 181–86. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w8-181-2018.
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<p><strong>Abstract.</strong> Systematic inventory of glaciers is required for a variety of applications needed for the comprehensive development of the Himalayan region such as: a) disaster warning, b) estimation of irrigation potential, c) planning and operation of mini and micro hydroelectric power stations, etc.</p><p> A systematic inventory of the Himalayan glaciers at 1<span class="thinspace"></span>:<span class="thinspace"></span>50,000 scale was created for Indus, Ganga and Brahmaputra basins using Indian Remote Sensing Satellite data and attempted to modified global standards in GIS environment (Sharma et al, 2013). A robust, user- friendly web-based Himalayan Glacier Information System (HGIS), a first of its kind in the country is developed which facilitates any user to selectively display, query, analyse, compose maps and graphs and print, spatial and <i>aspatial</i> information on glaciers relevant to respective interests.</p><p> The HGIS architecture is based on Open Geospatial Consortium (OGC) standards and utilises OpenGeo Suite bundled software comprising of Postgresql (PostGIS), Geoserver, GeoWebCache and GeoExplorer each of those having a different function (Anonymous 2010). The spatial and aspatial glacier data sets were stored in a pre-defined format (Sharma et al, 2008) and imbibed into spatially enabled database (PostGIS), having sophisticated functions for spatial data analysis and query. For publishing the data on web page OGC-compliant services are used.</p><p> The HGIS information content comprise of a) glacier inventory maps and b) inventory data sheet. The map displays the glacier morphology features like accumulation zone and ablation (ice exposed and debris covered) zones, snout location, de-glaciated valleys, moraines and glacier lakes. The basin, sub-basin and administrative boundaries form the background. The inventory data sheet attributes for each glacier provides information on glacier Location, Identification, Dimension, Orientation, Elevation, Classification, etc. The spatial map and datasheet are linked by unique glacier identification number (galc_id) which is a key field present in all corresponding glacier related point, polygon or line layers. All the glacier attribute were made amenable to query and analysis by users. HGIS represents a significant step towards mapping and compiling individual glacier level inventory data in spatial form to fill the void in data and information on the status of Glaciers in the Himalaya and Trans-Himalayan Karakoram region. HGIS provides a basis for assessing the glacier inventory data which has applications in studies related to climate change, water resource planning, hydropower site selection and mitigation of glacial lake outburst flood (GLOF) hazards.</p>
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Rastogi, G., i Ajai. "Comparison of energy balance on Gangotri and Chhota Shigri Glaciers". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-8 (28.11.2014): 537–42. http://dx.doi.org/10.5194/isprsarchives-xl-8-537-2014.
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Surface energy balance of a glacier governs the physical processes taking place at the surface-atmosphere interface and connects ice ablation/accumulation to climate variability. To understand the response of Himalayan glaciers to climatic variability, a study was taken to formulate energy balance equation on two of the Indian Himalayan glaciers, one each from Indus and Ganga basins, which have different climatic and physiographic conditions. Study was carried out over Gangotri glacier (Ganga basin) and Chhota Shigri(CS) glacier from Chandra sub-basin (Indus basin). Gangotri glacier is one of the largest glaciers in the central Himalaya located in Uttarkashi District, Uttarakhand, India. Chhota Shigri glacier of Chandra sub-basin lies in Lahaul and Spiti valley of Himachal Pradesh. Energy balance components have been computed using inputs derived from satellite data, AWS (Automatic Weather Station) data and field measurements. Different components of energy balance computed are net radiation (includes net shortwave and net longwave radiation), sensible heat flux and latent heat flux. In this study comparison has been made for each of the above energy balance components as well as total energy for the above glaciers for the months of November and December, 2011. It is observed that net radiation in Gangotri glacier is higher by approximately 43 % in comparison to Chhota Shigri glacier; Sensible heat flux is lesser by 77 %; Latent heat flux is higher by 66 % in the month of November 2011. Comparison in the month of December shows that net radiation in Gangotri glacier is higher by approximately 22 % from Chhota Shigri glacier; Sensible heat flux is lesser by 90 %; Latent heat flux is higher by 3 %.Total energy received at the glacier surface and contributes for melting is estimated to be around 32 % higher in Gangotri than Chhota Shigri glacier in November, 2011 and 1.25 % higher in December, 2011. The overall results contribute towards higher melting rate in November and December, 2011 in Gangotri than Chhota Shigri glacier.
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Veh, Georg, Oliver Korup i Ariane Walz. "Hazard from Himalayan glacier lake outburst floods". Proceedings of the National Academy of Sciences 117, nr 2 (30.12.2019): 907–12. http://dx.doi.org/10.1073/pnas.1914898117.
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Sustained glacier melt in the Himalayas has gradually spawned more than 5,000 glacier lakes that are dammed by potentially unstable moraines. When such dams break, glacier lake outburst floods (GLOFs) can cause catastrophic societal and geomorphic impacts. We present a robust probabilistic estimate of average GLOFs return periods in the Himalayan region, drawing on 5.4 billion simulations. We find that the 100-y outburst flood has an average volume of 33.5+3.7/−3.7 × 106 m3 (posterior mean and 95% highest density interval [HDI]) with a peak discharge of 15,600+2,000/−1,800 m3⋅s−1. Our estimated GLOF hazard is tied to the rate of historic lake outbursts and the number of present lakes, which both are highest in the Eastern Himalayas. There, the estimated 100-y GLOF discharge (∼14,500 m3⋅s−1) is more than 3 times that of the adjacent Nyainqentanglha Mountains, and at least an order of magnitude higher than in the Hindu Kush, Karakoram, and Western Himalayas. The GLOF hazard may increase in these regions that currently have large glaciers, but few lakes, if future projected ice loss generates more unstable moraine-dammed lakes than we recognize today. Flood peaks from GLOFs mostly attenuate within Himalayan headwaters, but can rival monsoon-fed discharges in major rivers hundreds to thousands of kilometers downstream. Projections of future hazard from meteorological floods need to account for the extreme runoffs during lake outbursts, given the increasing trends in population, infrastructure, and hydropower projects in Himalayan headwaters.
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Thakur, P. K., V. Garg, B. R. Nikam, S. Singh, A. Chouksey, P. R. Dhote, S. P. Aggarwal, P. Chauhan i A. S. Kumar. "SNOW COVER AND GLACIER DYNAMICS STUDY USING C-AND L-BAND SAR DATASETS IN PARTS OF NORTH WEST HIMALAYA". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-5 (19.11.2018): 375–82. http://dx.doi.org/10.5194/isprs-archives-xlii-5-375-2018.
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<p><strong>Abstract.</strong> The seasonal snow cover and permanent ice in form of Himalayan glaciers provide fresh water to many perineal rivers of Himalayas. The melt water from seasonal snow and glaciers, especially during of 15 March to 15 June acts as important source of water for drinking, hydropower and irrigation requirements of many areas in North India. This work has highlights the use of C-band Synthetic Aperture Radar (SAR) data from RISAT-1, Sentinel-1A and 1B satellites and ALOS-PALSAR-2 PolInSAR data for snow cover and glacier dynamics study for parts of North West Himalaya. Glacier velocity was derived using InSAR based method using 6 day temporal interval images from Sentinel-1 satellites and 14 day interval for PALSAR-2 satellite. High coherence was obtained for main glacier in both the data sets, which resulted accurate line of site (LOS) glacier velocity estimates for test glaciers. These InSAR data glacier velocity results are obtained after a gap of 21 years. Glacier facies was estimated using multi-temporal SAR image composition based classification. All these maps were verified by extensive ground surveys done at these sites during 2014–2017. The time series data of C-band SAR in VV/VH polarisation was also used to map snow cover in test basins of Bhagirathi and Beas River. The VV/VH data clearly shows difference between dry and wet snow, thus helping in improved snow cover mapping using SAR data. This study will help in refining algorithms to be used for such studies using upcoming NASA-ISRO SAR (NISAR) mission.</p>
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Nuimura, Takayuki, Koji Fujita, Satoru Yamaguchi i Rishi R. Sharma. "Elevation changes of glaciers revealed by multitemporal digital elevation models calibrated by GPS survey in the Khumbu region, Nepal Himalaya, 1992-2008". Journal of Glaciology 58, nr 210 (2012): 648–56. http://dx.doi.org/10.3189/2012jog11j061.
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AbstractDue to remoteness and high altitude, only a few ground-based glacier change studies are available in high-mountain areas in the Himalaya. However, digital elevation models based on remotely sensed data (RS-DEMs) provide feasible opportunities to evaluate how fast Himalayan glaciers are changing. Here we compute elevation changes in glacier surface (total area 183.3 km2) in the Khumbu region, Nepal Himalaya, for the period 1992-2008 using multitemporal RS-DEMs and a map-derived DEM calibrated with differential GPS survey data in 2007. Elevation change is calculated by generating a weighted least-squares linear regression model. Our method enables us to provide the distribution of uncertainty of the elevation change. Debris-covered areas show large lowering rates. The spatial distribution of elevation change shows that the different wastage features of the debris-covered glaciers depend on their scale, slope and the existence of glacial lakes. The elevation changes of glaciers in the eastern Khumbu region are in line with previous studies. The regional average mass balance of -0.40 ± 0.25 m w.e.a-1 for the period 1992-2008 is consistent with a global value of about -0.55 m w.e. a-1 for the period 1996-2005.
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Bhambri, Rakesh, Tobias Bolch, Ravinder Kumar Chaujar i Subhash Chandra Kulshreshtha. "Glacier changes in the Garhwal Himalaya, India, from 1968 to 2006 based on remote sensing". Journal of Glaciology 57, nr 203 (2011): 543–56. http://dx.doi.org/10.3189/002214311796905604.
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AbstractGlacier outlines are mapped for the upper Bhagirathi and Saraswati/Alaknanda basins of the Garhwal Himalaya using Corona and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite images acquired in 1968 and 2006, respectively. A subset of glaciers was also mapped using Landsat TM images acquired in 1990. Glacier area decreased from 599.9 ± 15.6 km2(1968) to 572.5 ± 18.0 km2(2006), a loss of 4.6 ± 2.8%. Glaciers in the Saraswati/Alaknanda basin and upper Bhagirathi basin lost 18.4 ± 9.0 km2(5.7 ± 2.7%) and 9.0 ± 7.7 km2(3.3 ± 2.8%), respectively, from 1968 to 2006. Garhwal Himalayan glacier retreat rates are lower than previously reported. More recently (1990–2006), recession rates have increased. The number of glaciers in the study region increased from 82 in 1968 to 88 in 2006 due to fragmentation of glaciers. Smaller glaciers (<1 km2) lost 19.4 ± 2.5% (0.51 ± 0.07% a−1) of their ice, significantly more than for larger glaciers (>50 km2) which lost 2.8 ± 2.7% (0.074 ± 0.071 % a−1). From 1968 to 2006, the debris-covered glacier area increased by 17.8 ± 3.1% (0.46 ± 0.08% a−1) in the Saraswati/Alaknanda basin and 11.8 ± 3.0% (0.31 ± 0.08% a−1) in the upper Bhagirathi basin. Climate records from Mukhim (∼1900 m a.s.l.) and Bhojbasa (∼3780 m a.s.l.) meteorological stations were used to analyze climate conditions and trends, but the data are too limited to make firm conclusions regarding glacier–climate interactions.
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Singh, Pratap, Umesh K. Haritashya i Naresh Kumar. "Meteorological study for Gangotri Glacier and its comparison with other high altitude meteorological stations in central Himalayan region". Hydrology Research 38, nr 1 (1.02.2007): 59–77. http://dx.doi.org/10.2166/nh.2007.028.
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In spite of the vital role of high altitude climatology in melting of snow and glaciers, retreat or advancement of glaciers, flash floods, erosion and sediment transport, etc., weather conditions are not much studied for the high altitude regions of Himalayas. In this study, a comprehensive meteorological analysis has been made for the Gangotri Meteorological Station (Bhagirathi Valley, Garhwal Himalayas) using data observed for four consecutive melt seasons (2000–2003) covering a period from May to October for each year. The collected meteorological data includes rainfall, temperature, wind speed and direction, relative humidity, sunshine hours and evaporation. The results and their distribution over the different melt seasons were compared with available meteorological records for Dokriani Meteorological Station (Dingad Valley, Garhwal Himalayas) and Pyramid Meteorological Station (Khumbu Valley, Nepal Himalayas). The magnitude and distribution of temperature were found to be similar for different Himalayan regions, while rainfall varied from region to region. The influence of the monsoon was meagre on the rainfall in these areas. July was recorded to be the warmest month for all the regions and, in general, August had the maximum rainfall. For all the stations, daytime up-valley wind speeds were 3 to 4 times stronger than the nighttime down-valley wind speeds. It was found that the Gangotri Glacier area experienced relatively low humidity and high evaporation rates as compared to other parts of the Himalayas. Such analysis reveals the broad meteorological characteristics of the high altitude areas of the Central Himalayan region.
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King, Owen, Duncan J. Quincey, Jonathan L. Carrivick i Ann V. Rowan. "Spatial variability in mass loss of glaciers in the Everest region, central Himalayas, between 2000 and 2015". Cryosphere 11, nr 1 (3.02.2017): 407–26. http://dx.doi.org/10.5194/tc-11-407-2017.
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Abstract. Region-wide averaging of Himalayan glacier mass change has masked any catchment or glacier-scale variability in glacier recession; thus the role of a number of glaciological processes in glacier wastage remains poorly understood. In this study, we quantify mass loss rates over the period 2000–2015 for 32 glaciers across the Everest region and assess how future ice loss is likely to differ depending on glacier hypsometry. The mean mass balance of all 32 glaciers in our sample was −0.52 ± 0.22 m water equivalent (w.e.) a−1. The mean mass balance of nine lacustrine-terminating glaciers (−0.70 ± 0.26 m w.e. a−1) was 32 % more negative than land-terminating, debris-covered glaciers (−0.53 ± 0.21 m w.e. a−1). The mass balance of lacustrine-terminating glaciers is highly variable (−0.45 ± 0.13 to −0.91 ± 0.22 m w.e. a−1), perhaps reflecting glacial lakes at different stages of development. To assess the importance of hypsometry on glacier response to future temperature increases, we calculated current (Dudh Koshi – 0.41, Tama Koshi – 0.43, Pumqu – 0.37) and prospective future glacier accumulation area Ratios (AARs). IPCC AR5 RCP 4.5 warming (0.9–2.3 °C by 2100) could reduce AARs to 0.29 or 0.08 in the Tama Koshi catchment, 0.27 or 0.17 in the Dudh Koshi catchment and 0.29 or 0.18 in the Pumqu catchment. Our results suggest that glacial lake expansion across the Himalayas could expedite ice mass loss and the prediction of future contributions of glacial meltwater to river flow will be complicated by spatially variable glacier responses to climate change.
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Bolch, T., T. Pieczonka i D. I. Benn. "Longest time series of glacier mass changes in the Himalaya based on stereo imagery". Cryosphere Discussions 4, nr 4 (20.12.2010): 2593–613. http://dx.doi.org/10.5194/tcd-4-2593-2010.
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Abstract. Mass loss of Himalayan glaciers has wide-ranging consequences such as declining water resources, sea level rise and an increasing risk of glacial lake outburst floods (GLOFs). The assessment of the regional and global impact of glacier changes in the Himalaya is, however, hampered by a lack of mass balance data for most of the range. Multi-temporal digital terrain models (DTMs) allow glacier mass balance to be calculated since the availability of stereo imagery. Here we present the longest time series of mass changes in the Himalaya and show the high value of early stereo spy imagery such as Corona (years 1962 and 1970) aerial images and recent high resolution satellite data (Cartosat-1) to calculate a time series of glacier changes south of Mt. Everest, Nepal. We reveal that the glaciers are significantly losing mass with an increasing rate since at least ~1970, despite thick debris cover. The specific mass loss is 0.32 ± 0.08 m w.e. a−1, however, not higher than the global average. The spatial patterns of surface lowering can be explained by variations in debris-cover thickness, glacier velocity, and ice melt due to exposed ice cliffs and ponds.
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Mehta, Manish, D. P. Dobhal i M. P. S. Bisht. "Change of Tipra Glacier in the Garhwal Himalaya, India, between 1962 and 2008". Progress in Physical Geography: Earth and Environment 35, nr 6 (30.06.2011): 721–38. http://dx.doi.org/10.1177/0309133311411760.
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Systematic observations of Himalayan glaciers over the last few decades provide reliable indications of continuous shrinkage of most of the glaciers. Changes in mass, volume, area and length of glaciers are reported, but an up-to-date regional assessment of glacier changes is lacking. In the present study, satellite data, maps and ground-based measurements have been used to obtain the snout retreat and surface changes of the Tipra Glacier in the Alaknanda river basin of the Garhwal Himalaya for the period 1962–2008. The study reveals that a large part of the glacier has been detached from the main trunk and separated into the Tipra (7.5 km2) and Rataban (7.4 km2) Glaciers as it had one outlet (snout) in 1987. Between 1962 and 2002 estimated surface area reduced by ~18% and snout retreat was ~535 m with an average rate of 13.4 m a−1. Measurement of snout positions of the Tipra and Rataban Glaciers from 2002 to 2008 indicates an enhanced annual retreat of 21.3 and 21.2 m a−1, respectively. Total frontal area vacated during this period was calculated to be 0.084 km2 for Tipra Glacier and 0.028 km2 for Rataban Glacier. The estimated Equilibrium Line Altitude (ELA) rise was 76 m for the Tipra Glacier and 57 m for the Rataban Glacier. Accumulation Area Ratio (AAR) was calculated as 0.47 for the Tipra Glacier and 0.49 for the Rataban Glacier, during the study period. The observations compared with the other studies carried out in the region show a significant reduction in glacier areas. The increased retreat rate of glacier snouts is probably a direct consequence of global warming. The present snouts of the Tipra and Rataban Glaciers are located at altitudes of 3865 and 4120 m, respectively.
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Ye, Qinghua, Tandong Yao, Shichang Kang, Feng Chen i Jinghua Wang. "Glacier variations in the Naimona’nyi region, western Himalaya, in the last three decades". Annals of Glaciology 43 (2006): 385–89. http://dx.doi.org/10.3189/172756406781812032.
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AbstractThis work quantifies glacier variations in the Naimona’nyi area of the western Himalaya by integrating glacier spatial data from ASTER and the Landsat series of satellite imagery at four different times: 1976, 1990, 1999 and 2003. Comparison of the results from individual images with those from the integrated method indicates that the integrated approach provides a better result. Glacier variations were mapped and analyzed; discrepancies between images could be detected and removed from the integrated data using remap tables in Arc/Info grid both graphically and numerically. Our results show that glaciers in the region both retreated and advanced during the last 28 years; however, retreat dominates. The variation of glaciers in the western Himalayan region is dramatic compared with other regions in high Asia. From 1976 to 2003, glacier area decreased from 84.41 km2 to 77.29 km2. Sequential images show that glacier areas shrank by 0.17, 0.19 and 0.77 km2 a−1, on average, during the periods 1976–90, 1990–99 and 1999–2003, respectively, suggesting that glacier retreat has accelerated.
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Bolch, T., T. Pieczonka i D. I. Benn. "Multi-decadal mass loss of glaciers in the Everest area (Nepal Himalaya) derived from stereo imagery". Cryosphere 5, nr 2 (20.04.2011): 349–58. http://dx.doi.org/10.5194/tc-5-349-2011.
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Abstract. Mass loss of Himalayan glaciers has wide-ranging consequences such as changing runoff distribution, sea level rise and an increasing risk of glacial lake outburst floods (GLOFs). The assessment of the regional and global impact of glacier changes in the Himalaya is, however, hampered by a lack of mass balance data for most of the range. Multi-temporal digital terrain models (DTMs) allow glacier mass balance to be calculated. Here, we present a time series of mass changes for ten glaciers covering an area of about 50 km2 south and west of Mt. Everest, Nepal, using stereo Corona spy imagery (years 1962 and 1970), aerial images and recent high resolution satellite data (Cartosat-1). This is the longest time series of mass changes in the Himalaya. We reveal that the glaciers have been significantly losing mass since at least 1970, despite thick debris cover. The specific mass loss for 1970–2007 is 0.32 ± 0.08 m w.e. a−1, however, not higher than the global average. Comparisons of the recent DTMs with earlier time periods indicate an accelerated mass loss. This is, however, hardly statistically significant due to high uncertainty, especially of the lower resolution ASTER DTM. The characteristics of surface lowering can be explained by spatial variations of glacier velocity, the thickness of the debris-cover, and ice melt due to exposed ice cliffs and ponds.
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Barker, Joel D., Susan Kaspari, Paolo Gabrielli, Anna Wegner, Emilie Beaudon, M. Roxana Sierra-Hernández i Lonnie Thompson. "Drought-induced biomass burning as a source of black carbon to the central Himalaya since 1781 CE as reconstructed from the Dasuopu ice core". Atmospheric Chemistry and Physics 21, nr 7 (13.04.2021): 5615–33. http://dx.doi.org/10.5194/acp-21-5615-2021.
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Abstract. Himalayan glaciers are melting due to atmospheric warming, with the potential to limit access to water for more than 25 % of the global population that resides in these glacier meltwater catchments. Black carbon has been implicated as a factor that is contributing to Himalayan glacier melt, but its sources and mechanisms of delivery to the Himalayas remain controversial. Here, we provide a 211-year ice core record spanning 1781–1992 CE for refractory black carbon (rBC) deposition from the Dasuopu glacier ice core that has to date provided the highest-elevation ice core record (7200 m). We report an average rBC concentration of 1.5 µg L−1 (SD=5.0, n=1628) over the 211-year period. An increase in the frequency and magnitude of rBC deposition occurs after 1877 CE, accompanied by decreased snow accumulation associated with a shift in the North Atlantic Oscillation Index to a positive phase. Typically, rBC is deposited onto Dasuopu glacier during the non-monsoon season, and short-lived increases in rBC concentration are associated with periods of drought within neighboring regions in northwestern India, Afghanistan, and Pakistan. Using a combination of spectral and back-trajectory analyses, as well as a comparison with a concurrent analysis of trace metals at equivalent depths in the same ice core, we show that biomass burning resulting from dry conditions is a source of rBC to the central Himalaya and is responsible for deposition that is up to 60 times higher than the average rBC concentration over the time period analyzed. We suggest that biomass burning is a significant source of rBC to the central Himalaya and that the rBC record can be used to identify periods of drought in nearby regions that are upwind of Dasuopu glacier.
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Chen, W., T. Doko, C. Liu, T. Ichinose, H. Fukui, Q. Feng i P. Gou. "Changes in Rongbuk lake and Imja lake in the Everest region of Himalaya". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-2 (18.12.2014): 259–66. http://dx.doi.org/10.5194/isprsarchives-xl-2-259-2014.
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The Himalaya holds the world record in terms of range and elevation. It is one of the most extensively glacierized regions in the world except the Polar Regions. The Himalaya is a region sensitive to climate change. Changes in the glacial regime are indicators of global climate changes. Since the second half of the last century, most Himalayan glaciers have melted due to climate change. These changes directly affected the changes of glacial lakes in the Himalayan region due to the glacier retreat. New glacial lakes are formed, and a number of them have expanded in the Everest region of the Himalayas. This paper focuses on the two glacial lakes which are Imja Lake, located at the southern slope, and Rongbuk Lake, located at the northern slope in the Mt. Everest region, Himalaya to present the spatio-temporal changes from 1976 to 2008. Topographical conditions between two lakes were different (Kruskal-Wallis test, <i>p</i> < 0.05). Rongbuk Lake was located at 623 m higher than Imja Lake, and radiation of Rongbuk Lake was higher than the Imja Lake. Although size of Imja Lake was larger than the Rongbuk Lake in 2008, the growth speed of Rongbuk Lake was accelerating since 2000 and exceeds Imja Lake in 2000–2008. This trend of expansion of Rongbuk Lake is anticipated to be continued in the 21st century. Rongbuk Lake would be the biggest potential risk of glacial lake outburst flood (GLOF) at the Everest region of Himalaya in the future.
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Sato, Yota, Koji Fujita, Hiroshi Inoue i Akiko Sakai. "Land- to lake-terminating transition triggers dynamic thinning of a Bhutanese glacier". Cryosphere 16, nr 6 (1.07.2022): 2643–54. http://dx.doi.org/10.5194/tc-16-2643-2022.
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Abstract. There have been rapid increases in both the number and expansion of the proglacial lakes across High Mountain Asia. However, the relationship between proglacial lakes and glacier dynamics remains unclear in the Himalayan region. Here we present the surface elevation, flow-velocity changes, and proglacial lake expansion of Thorthormi and Lugge glaciers in the Lunana region, Bhutanese Himalaya, during the 2000–2018 period using photogrammetry and GPS survey data. The lake expansion and surface lowering rates and flow-velocity field of Lugge Glacier, a lake-terminating glacier, have remained approximately constant since 2000. Conversely, there have been accelerated proglacial lake expansion and a 2-fold increase in the thinning rate of Thorthormi Glacier since 2011, as well as a considerable speed-up in the flow-velocity field (>150 m a−1). We reveal that the lake formation and transition of Thorthormi Glacier from a land- to lake-terminating glacier have triggered glacier speed-up and rapid thinning via a positive (compressive) to negative (extensional) change in the emergence velocities. This study provides the first evidence of dynamic glacier changes that are associated with proglacial lake formation across the Himalayan region.
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Sam, Lydia, Anshuman Bhardwaj, Shaktiman Singh i Rajesh Kumar. "Remote sensing flow velocity of debris-covered glaciers using Landsat 8 data". Progress in Physical Geography: Earth and Environment 40, nr 2 (13.07.2015): 305–21. http://dx.doi.org/10.1177/0309133315593894.
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Changes in ice velocity of a glacier regulate its mass balance and dynamics. The estimation of glacier flow velocity is therefore an important aspect of temporal glacier monitoring. The utilisation of conventional ground-based techniques for detecting glacier surface flow velocity in the rugged and alpine Himalayan terrain is extremely difficult. Remote sensing-based techniques can provide such observations on a regular basis for a large geographical area. Obtaining freely available high quality remote sensing data for the Himalayan regions is challenging. In the present work, we adopted a differential band composite approach, for the first time, in order to estimate glacier surface velocity for non-debris and supraglacial debris covered areas of a glacier, separately. We employed various bandwidths of the Landsat 8 data for velocity estimation using the COSI-Corr (co-registration of optically sensed images and correlation) tool. We performed the accuracy assessment with respect to field measurements for two glaciers in the Indian Himalaya. The panchromatic band worked best for non-debris parts of the glaciers while band 6 (SWIR – short wave infrared) performed best in case of debris cover. We correlated six temporal Landsat 8 scenes in order to ensure the performance of the proposed algorithm on monthly as well as yearly timescales. We identified sources of error and generated a final velocity map along with the flow lines. Over- and underestimates of the yearly glacier velocity were found to be more in the case of slow moving areas with annual displacements less than 5 m. Landsat 8 has great capabilities for such velocity estimation work for a large geographic extent because of its global coverage, improved spectral and radiometric resolutions, free availability and considerable revisit time.
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Casey, K. A., A. Kääb i D. I. Benn. "Geochemical characterization of supraglacial debris via in situ and optical remote sensing methods: a case study in Khumbu Himalaya, Nepal". Cryosphere 6, nr 1 (19.01.2012): 85–100. http://dx.doi.org/10.5194/tc-6-85-2012.
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Abstract. Surface glacier debris samples and field spectra were collected from the ablation zones of Nepal Himalaya Ngozumpa and Khumbu glaciers in November and December 2009. Geochemical and mineral compositions of supraglacial debris were determined by X-ray diffraction and X-ray fluorescence spectroscopy. This composition data was used as ground truth in evaluating field spectra and satellite supraglacial debris composition and mapping methods. Satellite remote sensing methods for characterizing glacial surface debris include visible to thermal infrared hyper- and multispectral reflectance and emission signature identification, semi-quantitative mineral abundance indicies and spectral image composites. Satellite derived supraglacial debris mineral maps displayed the predominance of layered silicates, hydroxyl-bearing and calcite minerals on Khumbu Himalayan glaciers. Supraglacial mineral maps compared with satellite thermal data revealed correlations between glacier surface composition and glacier surface temperature. Glacier velocity displacement fields and shortwave, thermal infrared false color composites indicated the magnitude of mass flux at glacier confluences. The supraglacial debris mapping methods presented in this study can be used on a broader scale to improve, supplement and potentially reduce errors associated with glacier debris radiative property, composition, areal extent and mass flux quantifications.
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Racoviteanu, Adina E., Lindsey Nicholson i Neil F. Glasser. "Surface composition of debris-covered glaciers across the Himalaya using linear spectral unmixing of Landsat 8 OLI imagery". Cryosphere 15, nr 9 (29.09.2021): 4557–88. http://dx.doi.org/10.5194/tc-15-4557-2021.
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Abstract. The Himalaya mountain range is characterized by highly glacierized, complex, dynamic topography. The ablation area of Himalayan glaciers often features a highly heterogeneous debris mantle comprising ponds, steep and shallow slopes of various aspects, variable debris thickness, and exposed ice cliffs associated with differing ice ablation rates. Understanding the composition of the supraglacial debris cover is essential for a proper understanding of glacier hydrology and glacier-related hazards. Until recently, efforts to map debris-covered glaciers from remote sensing focused primarily on glacier extent rather than surface characteristics and relied on traditional whole-pixel image classification techniques. Spectral unmixing routines, rarely used for debris-covered glaciers, allow decomposition of a pixel into constituting materials, providing a more realistic representation of glacier surfaces. Here we use linear spectral unmixing of Landsat 8 Operational Land Imager (OLI) images (30 m) to obtain fractional abundance maps of the various supraglacial surfaces (debris material, clean ice, supraglacial ponds and vegetation) across the Himalaya around the year 2015. We focus on the debris-covered glacier extents as defined in the database of global distribution of supraglacial debris cover. The spectrally unmixed surfaces are subsequently classified to obtain maps of composition of debris-covered glaciers across sample regions. We test the unmixing approach in the Khumbu region of the central Himalaya, and we evaluate its performance for supraglacial ponds by comparison with independently mapped ponds from high-resolution Pléiades (2 m) and PlanetScope imagery (3 m) for sample glaciers in two other regions with differing topo-climatic conditions. Spectral unmixing applied over the entire Himalaya mountain range (a supraglacial debris cover area of 2254 km2) indicates that at the end of the ablation season, debris-covered glacier zones comprised 60.9 % light debris, 23.8 % dark debris, 5.6 % clean ice, 4.5 % supraglacial vegetation, 2.1 % supraglacial ponds, and small amounts of cloud cover (2 %), with 1.2 % unclassified areas. The spectral unmixing performed satisfactorily for the supraglacial pond and vegetation classes (an F score of ∼0.9 for both classes) and reasonably for the debris classes (F score of 0.7). Supraglacial ponds were more prevalent in the monsoon-influenced central-eastern Himalaya (up to 4 % of the debris-covered area) compared to the monsoon-dry transition zone (only 0.3 %) and in regions with lower glacier elevations. Climatic controls (higher average temperatures and more abundant precipitation), coupled with higher glacier thinning rates and lower average glacier velocities, further favour pond incidence and the development of supraglacial vegetation. With continued advances in satellite data and further method refinements, the approach presented here provides avenues towards achieving large-scale, repeated mapping of supraglacial features.
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BHATTACHARYA, ATANU, TOBIAS BOLCH, KRITI MUKHERJEE, TINO PIECZONKA, JAN KROPÁČEK i MANFRED F. BUCHROITHNER. "Overall recession and mass budget of Gangotri Glacier, Garhwal Himalayas, from 1965 to 2015 using remote sensing data". Journal of Glaciology 62, nr 236 (9.09.2016): 1115–33. http://dx.doi.org/10.1017/jog.2016.96.
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ABSTRACTThinning rates for the debris-covered Gangotri Glacier and its tributary glaciers during the period 1968–2014, length variation and area vacated at the snout from 1965 to 2015, and seasonal variation of ice-surface velocity for the last two decades have been investigated in this study. It was found that the mass loss of Gangotri and its tributary glaciers was slightly less than those reported for other debris-covered glaciers in the Himalayan regions. The average velocity during 2006–14 decreased by ~6.7% as compared with that during 1993–2006. The debris-covered area of the main trunk of Gangotri Glacier increased significantly from 1965 until 2015 with the maximum rate of increase (0.8 ± 0.2 km2 a−1) during 2006–15. The retreat (~9.0 ± 3.5 m a−1) was less in recent years (2006–2015) but the down-wasting (0.34 ± 0.2 m a−1) in the same period (2006–2014) was higher than that (0.20 ± 0.1 m a−1) during 1968–2006. The study reinforced the established fact that the glacier length change is a delayed response to climate change and, in addition, is affected by debris cover, whereas glacier mass balance is a more direct and immediate response. Therefore, it is recommended to study the glacier mass balance and not only the glacier extent, to conclude about a glacier's response to climate change.
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Zhang, S., S. Hou, X. Ma, D. Qin i T. Chen. "Culturable bacteria in Himalayan glacial ice in response to atmospheric circulation". Biogeosciences 4, nr 1 (10.01.2007): 1–9. http://dx.doi.org/10.5194/bg-4-1-2007.
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Abstract. Only recently has specific attention been given to culturable bacteria in Tibetan glaciers, but their relation to atmospheric circulation is less understood yet. Here we present the results of culturable bacteria preserved in an ice core drilled from the East Rongbuk (ER) glacier, Himalayas. The average concentrations of culturable bacteria are 5.0, 0.8, 0.1 and 0.7 CFU mL−1 for the glacier ice deposited during the premonsoon, monsoon, postmonsoon and winter seasons, respectively. The high concentration of culturable bacteria in ER glacier deposited during the premonsoon season is attributed to the transportation of continental dust stirred up by the frequent dust storms during spring. This is also confirmed by the spatial distribution of culturable bacteria in Tibetan glaciers. Continental dust originated from the Northwest China accounts for the high abundance of culturable bacteria in the northern Tibetan Plateau, while monsoon moisture exerts great influence on culturable bacteria with low abundance in the southern plateau. The numbers of representatives with different ARDRA patterns from RFLP analysis are 10, 15, 1 and 2 for the glacial ice deposited during the premonsoon, monsoon, postmonsoon and winter seasons, respectively, suggesting that culturable bacteria deposited in ER glacier during monsoon season are more diverse than that deposited during the other seasons, possibly due to their derivation from both marine air masses and local or regional continental sources, while culturable bacteria deposited during the other seasons are from only one possible origin that is transported by westerlies. Our results show the first report of seasonal variations of abundance and species diversity of culturable bacteria recovered from glacial ice in the Himalayas, and we suggest that microorganisms in Himalayan ice might provide a potential new proxy for the reconstruction of atmospheric circulation.
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TAKEUCHI, Nozomu. "Glacial-biology in Himalayan Glaciers." Journal of the Japanese Society of Snow and Ice 63, nr 2 (2001): 181–89. http://dx.doi.org/10.5331/seppyo.63.181.
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