Journal articles on the topic 'Glaciers'
To see the other types of publications on this topic, follow the link: Glaciers.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Glaciers.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Lipar, Matej, Andrea Martín-Pérez, Jure Tičar, Miha Pavšek, Matej Gabrovec, Mauro Hrvatin, Blaž Komac, et al. "Subglacial carbonate deposits as a potential proxy for a glacier's former presence." Cryosphere 15, no. 1 (January 4, 2021): 17–30. http://dx.doi.org/10.5194/tc-15-17-2021.
Full textAbstract:
Abstract. The retreat of ice shelves and glaciers over the last century provides unequivocal evidence of recent global warming. Glacierets (miniature glaciers) and ice patches are important components of the cryosphere that highlight the global retreat of glaciers, but knowledge of their behaviour prior to the Little Ice Age is lacking. Here, we report the uranium–thorium age of subglacial carbonate deposits from a recently exposed surface previously occupied by the disappearing Triglav Glacier (southeastern European Alps) that may elucidate the glacier's presence throughout the entire Holocene. The ages suggest the deposits' possible preservation since the Last Glacial Maximum and Younger Dryas. These thin deposits, formed by regelation, are easily eroded if exposed during previous Holocene climatic optima. The age data indicate the glacier's present unprecedented level of retreat since the Last Glacial Maximum and the potential of subglacial carbonates as additional proxies to highlight the extraordinary nature of the current global climatic changes.
2
Letréguilly, Anne. "Relation between the Mass Balance of Western Canadian Mountain Glaciers and Meteorological Data." Journal of Glaciology 34, no. 116 (1988): 11–18. http://dx.doi.org/10.1017/s002214300000900x.
Full textAbstract:
AbstractThe mass balance, summer balance, winter balance, and equilibrium-line altitude of three Canadian glaciers (Peyto, Place, and Sentinel Glaciers) are compared with the meteorological records of neighbouring stations for the period 1966—84. While Peyto Glacier’s mass balance is almost entirely related to summer temperature, Sentinel Glacier’s mass balance is mostly controlled by winter precipitation. Place Glacier is influenced by both elements. Statistical reconstructions are presented for the three glaciers, using the best regression equations with the meteorological records since 1938.
3
Letréguilly, Anne. "Relation between the Mass Balance of Western Canadian Mountain Glaciers and Meteorological Data." Journal of Glaciology 34, no. 116 (1988): 11–18. http://dx.doi.org/10.3189/s002214300000900x.
Full textAbstract:
AbstractThe mass balance, summer balance, winter balance, and equilibrium-line altitude of three Canadian glaciers (Peyto, Place, and Sentinel Glaciers) are compared with the meteorological records of neighbouring stations for the period 1966—84. While Peyto Glacier’s mass balance is almost entirely related to summer temperature, Sentinel Glacier’s mass balance is mostly controlled by winter precipitation. Place Glacier is influenced by both elements. Statistical reconstructions are presented for the three glaciers, using the best regression equations with the meteorological records since 1938.
4
Weidick, A. "Investigating Greenland's glaciers." Rapport Grønlands Geologiske Undersøgelse 148 (January 1, 1990): 46–51. http://dx.doi.org/10.34194/rapggu.v148.8119.
Full textAbstract:
Investigations of Greenland's glaciers undertaken by GGU are primarily related to the exploitation of meltwater from the Inland lce and local glaciers in western Greenland, i.e. they are essentially related to glacier hydrology (Olesen & Braithwaite, 1989). The studies are therefore based on mass balance data combined with investigations of superglacial melt/refreezing and the determination of the internal mode of drainage. Related to this work is the documentation of short-term glacier changes at specific localities identified as being of special interest for hydropower from the point of view of glacier hazards, i.e. for example damage caused by tapping of ice dammed lakes or change of proglacial draining caused by change in the glacier's thickness and extent. Similar documentation of long-term glacier fluctuations provides a background for control and modelling of past glacier fluctuations. The procedures have a direct bearing on the calculation of scenarios for future events related to the individual localities or, in a regional sense, to the impact of changes in Greenland glaciers on global sea level (the 'greenhouse effect’).
5
Braithwaite, R. J., and S. C. B. Raper. "Estimating equilibrium-line altitude (ELA) from glacier inventory data." Annals of Glaciology 50, no. 53 (2009): 127–32. http://dx.doi.org/10.3189/172756410790595930.
Full textAbstract:
AbstractA glacier’s most fundamental altitude is the equilibrium-line altitude (ELA) because it divides the glacier into ablation and accumulation areas. The best parameterization of the ELA for glacier inventory is the balanced-budget ELA. We discuss direct estimation of balanced-budget ELA from mass-balance data for individual glaciers, and indirect estimation of balanced-budget ELA from simple topographic parameters available from the World Glacier Inventory (WGI), i.e. the area-median and maximum and minimum altitudes. Mass balance and ELA for individual glaciers are usually strongly correlated and we calculate balanced-budget ELA from the regression equation linking the two. We then compare balanced-budget ELA with area-median and mid-range altitudes for the 94 glaciers for which we have all the necessary data. The different ELA estimates agree well enough (±82 to ±125 m) to describe geographical variations in ELA and for application of glacier–climate models to glacier inventory data. Mid-range and area-median altitudes are already available for tens of thousands of glaciers in the current WGI and should be evaluated in future inventories.
6
Brugger, Keith A. "Non-Synchronous Response Of Rabots Glaciar and Storglaciaren To Recent Climatic Change." Annals of Glaciology 14 (1990): 331–32. http://dx.doi.org/10.3189/s0260305500008910.
Full textAbstract:
Rabots glaciär and Storglaciären are small valley glaciers located in the Kebnekaise massif of northern Sweden. Rabots glaciär flows west from the summit of Kebnekaise (2114 m) and Storglaciären flows east; thus regional climate affecting the glaciers is the same. The glaciers are of comparable size and geometry, although differences exist in the variation of ice thickness and the subglacial bedrock topography within the respective basins. The thickness of Rabots glaciär appears to be relatively uniform over much of its length and its bed smooth. The bed over which Storglaciären flows is characterized by a “riegel and basin” topography and ice thicknesses vary accordingly.Advance and retreat of the glaciers during the last 100 years has been documented by historical records and photographs, measurements of ice retreats, and detailed glacial and geological studies. Both advanced to their maximum 20th century extents around 1916. In their subsequent retreat, Rabots glaciär has lagged behind Storglaciären by 10 years.Mass-balance studies for the years 1981–87 suggest that while the “local” climate for each glacier is slightly different (in terms of the magnitude of acumulation and ablation), variations in local climate are synchronous. Non-synchronous response of the glaciers is therefore attributed to differences in glacier dynamics, which are quite apparent when velocity profiles are compared. Ice velocities on Rabots glaciär vary little from an average of −7.5 m/yr, resulting in a longitudinal strain rate, r, of about 6 × 10−3yr −1. In contrast, values for r on Storglaciären are as high as 2.5 × 10−2 yr−1 owing to greater ice velocities and variation in ice velocity. Since the response time of a glacier is proportional to 1/r, the lower strain rates found on Rabots glaciär probably account for its more sluggish retreat.A simple, non-diffusive, kinematic wave model is used to analyze the response of the glaciers to a step-like perturbation in mass balance. This model predicts that the response time of Storglaciären is on the order of 30 years and that a new steady-state profile would be attained in about 50 years. The predicted response time of Rabots glaciär is about 75 years, its new steady-state profile being reached after more than 100 years.More accurate analyses of each glacier's response to climatic change use a time-dependent numerical model which includes the effects of diffusion. The climatic forcing in these modelling efforts is represented by the changes in mass balance resulting from changes in the equilibrium line altitude (ELA). ELAs can be correlated to regional meteorological variables which in turn are used to create a “synthetic” record of ELA variations where necessary. Therefore climatic oscillations since the turn of the century can be simulated by the appropriate changes in ELA. Using synchronous variations of ELAs and their 1916 profiles as datum states, the modeled behavior of Rabots glaciär and Storglaciären shows that: (a) the rates of ice retreat for each glacier are in reasonable agreement with those observed; and (b) Rabots glaciär took slightly longer than Storglaciären to react to the slight warming that occurred shortly after their 1916 advance.
7
Brugger, Keith A. "Non-Synchronous Response Of Rabots Glaciar and Storglaciaren To Recent Climatic Change." Annals of Glaciology 14 (1990): 331–32. http://dx.doi.org/10.1017/s0260305500008910.
Full textAbstract:
Rabots glaciär and Storglaciären are small valley glaciers located in the Kebnekaise massif of northern Sweden. Rabots glaciär flows west from the summit of Kebnekaise (2114 m) and Storglaciären flows east; thus regional climate affecting the glaciers is the same. The glaciers are of comparable size and geometry, although differences exist in the variation of ice thickness and the subglacial bedrock topography within the respective basins. The thickness of Rabots glaciär appears to be relatively uniform over much of its length and its bed smooth. The bed over which Storglaciären flows is characterized by a “riegel and basin” topography and ice thicknesses vary accordingly. Advance and retreat of the glaciers during the last 100 years has been documented by historical records and photographs, measurements of ice retreats, and detailed glacial and geological studies. Both advanced to their maximum 20th century extents around 1916. In their subsequent retreat, Rabots glaciär has lagged behind Storglaciären by 10 years. Mass-balance studies for the years 1981–87 suggest that while the “local” climate for each glacier is slightly different (in terms of the magnitude of acumulation and ablation), variations in local climate are synchronous. Non-synchronous response of the glaciers is therefore attributed to differences in glacier dynamics, which are quite apparent when velocity profiles are compared. Ice velocities on Rabots glaciär vary little from an average of −7.5 m/yr, resulting in a longitudinal strain rate, r, of about 6 × 10−3yr −1. In contrast, values for r on Storglaciären are as high as 2.5 × 10−2 yr−1 owing to greater ice velocities and variation in ice velocity. Since the response time of a glacier is proportional to 1/r, the lower strain rates found on Rabots glaciär probably account for its more sluggish retreat. A simple, non-diffusive, kinematic wave model is used to analyze the response of the glaciers to a step-like perturbation in mass balance. This model predicts that the response time of Storglaciären is on the order of 30 years and that a new steady-state profile would be attained in about 50 years. The predicted response time of Rabots glaciär is about 75 years, its new steady-state profile being reached after more than 100 years. More accurate analyses of each glacier's response to climatic change use a time-dependent numerical model which includes the effects of diffusion. The climatic forcing in these modelling efforts is represented by the changes in mass balance resulting from changes in the equilibrium line altitude (ELA). ELAs can be correlated to regional meteorological variables which in turn are used to create a “synthetic” record of ELA variations where necessary. Therefore climatic oscillations since the turn of the century can be simulated by the appropriate changes in ELA. Using synchronous variations of ELAs and their 1916 profiles as datum states, the modeled behavior of Rabots glaciär and Storglaciären shows that: (a) the rates of ice retreat for each glacier are in reasonable agreement with those observed; and (b) Rabots glaciär took slightly longer than Storglaciären to react to the slight warming that occurred shortly after their 1916 advance.
8
Jones, Andrew G., Shaun A. Marcott, Andrew L. Gorin, Tori M. Kennedy, Jeremy D. Shakun, Brent M. Goehring, Brian Menounos, Douglas H. Clark, Matias Romero, and Marc W. Caffee. "Four North American glaciers advanced past their modern positions thousands of years apart in the Holocene." Cryosphere 17, no. 12 (December 21, 2023): 5459–75. http://dx.doi.org/10.5194/tc-17-5459-2023.
Full textAbstract:
Abstract. There is unambiguous evidence that glaciers have retreated from their 19th century positions, but it is less clear how far glaciers have retreated relative to their long-term Holocene fluctuations. Glaciers in western North America are thought to have advanced from minimum positions in the Early Holocene to maximum positions in the Late Holocene. We assess when four North American glaciers, located between 38–60∘ N, were larger or smaller than their modern (2018–2020 CE) positions during the Holocene. We measured 26 paired cosmogenic in situ 14C and 10Be concentrations in recently exposed proglacial bedrock and applied a Monte Carlo forward model to reconstruct plausible bedrock exposure–burial histories. We find that these glaciers advanced past their modern positions thousands of years apart in the Holocene: a glacier in the Juneau Icefield (BC, Canada) at ∼2 ka, Kokanee Glacier (BC, Canada) at ∼6 ka, and Mammoth Glacier (WY, USA) at ∼1 ka; the fourth glacier, Conness Glacier (CA, USA), was likely larger than its modern position for the duration of the Holocene until present. The disparate Holocene exposure–burial histories are at odds with expectations of similar glacier histories given the presumed shared climate forcings of decreasing Northern Hemisphere summer insolation through the Holocene followed by global greenhouse gas forcing in the industrial era. We hypothesize that the range in histories is the result of unequal amounts of modern retreat relative to each glacier's Holocene maximum position, rather than asynchronous Holocene advance histories. We explore the influence of glacier hypsometry and response time on glacier retreat in the industrial era as a potential cause of the non-uniform burial durations. We also report mean abrasion rates at three of the four glaciers: Juneau Icefield Glacier (0.3±0.3 mm yr−1), Kokanee Glacier (0.04±0.03 mm yr−1), and Mammoth Glacier (0.2±0.2 mm yr−1).
9
Etzelmüller, Bernd, and Johan Ludvig Sollid. "Glacier geomorphometry — an approach for analyzing long-term glacier surface changes using grid-based digital elevation models." Annals of Glaciology 24 (1997): 135–41. http://dx.doi.org/10.3189/s0260305500012064.
Full textAbstract:
This paper presents an approach to long-term glacier monitoring. Mathematical surface descriptors, such as altitude, slope and curvature (surface form) are used to classify and quantify glacier surface developments. The analysis is based on photogrammetically derived grid-based digital elevation models over a period of decades. This paper outlines the concept and applies it to five valley glaciers in Spitsbergen, Svalbard, which differ with respect to size, thermal regime and dynamics. The results reflect differences between the glaciers investigated which are attributable to glacier dynamics, in particular concerning the glacier’s possible surge behaviour during a period with retreat and mass losses.
10
Etzelmüller, Bernd, and Johan Ludvig Sollid. "Glacier geomorphometry — an approach for analyzing long-term glacier surface changes using grid-based digital elevation models." Annals of Glaciology 24 (1997): 135–41. http://dx.doi.org/10.1017/s0260305500012064.
Full textAbstract:
This paper presents an approach to long-term glacier monitoring. Mathematical surface descriptors, such as altitude, slope and curvature (surface form) are used to classify and quantify glacier surface developments. The analysis is based on photogrammetically derived grid-based digital elevation models over a period of decades. This paper outlines the concept and applies it to five valley glaciers in Spitsbergen, Svalbard, which differ with respect to size, thermal regime and dynamics. The results reflect differences between the glaciers investigated which are attributable to glacier dynamics, in particular concerning the glacier’s possible surge behaviour during a period with retreat and mass losses.
11
Chueca Cía, Javier. "Estimación de paleotemperaturas durante el Pleistoceno final: Pirineo Central español." Estudios Geográficos 53, no. 207 (June 30, 1992): 241–63. http://dx.doi.org/10.3989/egeogr.1992.i207.241.
Full textAbstract:
A partir de la determinación de la altitud de las líneas de nieve permanente (ELA/FLA) obtenidas mediante la utilización de evidencias geomorfológicas conservadas en antiguas superficies glaciadas y el estudio de la distribución espacial-altitudinal de glaciares rocosos, se ha procedido-por comparación con datos climáticos actuales- a la caracterización de las paleotemperaturas existentes en un amplio tramo del Pirineo Central meridional durante dos momentos, morfodinámicamente significativos, de su historia glaciar última: la fase terminal de glaciares de circo y el período tardiglaciar, ambos ubicables en el Pleistoceno Final y generadores de morfologías fácilmente reconocibles en extensos sectores de la Cadena (morrenas de boca de circo, glaciares rocosos). Los resultados ofrecen una primera aproximación general a las paleocondiciones térmicas desarrolladas en el área, marcadas por un descenso neto en las temperaturas medias anuales del orden de los 4'8/4'9°-3'5/3'6° para cada una de las dos etapas mencionadas. [fr] A partir de la détermination de l'altitude des lignes de neige permanente (ELA/FLA) obtenues grace a l'utilisation des évidences géomorphologiques conservées dans antiques superficies glaciées et de l'étude de la distribution spaciale -altitudinale des glaciers rocheux, on a procédé- par comparaison avec les donnés climatiques actuelles -a la caractérisation des paléotemperatures existentes dans un ample lot des Pyré nées C e ntrales m éridionales pendant deux mome nts, morphodinamiquement significatives, de sa derniere histoire glaciare: la phase terminale des glaciers de cirque et le période tardiglaciare, qu'on peut les situer dans le Pleistocene Supérieur et qui ont entrainés des morphologies trés facilement reconnaissables dans secteurs etendues de la Chaine (moraines de cirque, glaciers rocheux). Les résultats offrent une premiere approche générale au paléoconditions thermiques deroulées dans la zone, marquées pour une diminution nette dans les températures moyennes annuelles autour de 4'8º/4'9" - 3'5°/3'6° pour chacune des deux étapes mentionnés.
12
Sakakibara, Daiki, Shin Sugiyama, Takanobu Sawagaki, Sebastián Marinsek, and Pedro Skvarca. "Rapid retreat, acceleration and thinning of Glaciar Upsala, Southern Patagonia Icefield, initiated in 2008." Annals of Glaciology 54, no. 63 (2013): 131–38. http://dx.doi.org/10.3189/2013aog63a236.
Full textAbstract:
AbstractThe Patagonia Icefields are characterized by a large number of outlet glaciers calving into lakes and the ocean. In contrast to the recent intensive research activities on tidewater glaciers in other regions, very few observations have been made on calving glaciers in Patagonia. We analysed satellite images of Glaciar Upsala, the third largest freshwater calving glacier in the Southern Patagonia Icefield, to investigate changes in its front position, ice velocity and surface elevation from 2000 to 2011. Our analyses revealed a clear transition from a relatively stable phase to a rapidly retreating and fast-flowing condition in 2008. The glacier front receded by 2.9 km, and the ice velocity increased by 20–50%, over the 2008–11 period. We also found that the ice surface lowered at a rate of up to 39 m a−1 from 2006 to 2010. This magnitude and the rate of changes in the glacier front position, ice velocity and surface elevation are greater than previously reported for Glaciar Upsala, and comparable to recent observations of large tidewater glaciers in Greenland. Our data illustrate details of a rapidly retreating calving glacier in Patagonia that have been scarcely reported despite their importance to the mass budget of the Patagonia Icefields.
13
Marzeion, B., A. H. Jarosch, and J. M. Gregory. "Feedbacks and mechanisms affecting the global sensitivity of glaciers to climate change." Cryosphere 8, no. 1 (January 7, 2014): 59–71. http://dx.doi.org/10.5194/tc-8-59-2014.
Full textAbstract:
Abstract. Mass loss by glaciers has been an important contributor to sea level rise in the past, and is projected to contribute a substantial fraction of total sea level rise during the 21st century. Here, we use a model of the world's glaciers to quantify equilibrium sensitivities of global glacier mass to climate change, and to investigate the role of changes in glacier hypsometry for long-term mass changes. We find that 21st century glacier-mass loss is largely governed by the glacier's response to 20th century climate change. This limits the influence of 21st century climate change on glacier-mass loss, and explains why there are relatively small differences in glacier-mass loss under greatly different scenarios of climate change. The projected future changes in both temperature and precipitation experienced by glaciers are amplified relative to the global average. The projected increase in precipitation partly compensates for the mass loss caused by warming, but this compensation is negligible at higher temperature anomalies since an increasing fraction of precipitation at the glacier sites is liquid. Loss of low-lying glacier area, and more importantly, eventual complete disappearance of glaciers, strongly limit the projected sea level contribution from glaciers in coming centuries. The adjustment of glacier hypsometry to changes in the forcing strongly reduces the rates of global glacier-mass loss caused by changes in global mean temperature compared to rates of mass loss when hypsometric changes are neglected. This result is a second reason for the relatively weak dependence of glacier-mass loss on future climate scenario, and helps explain why glacier-mass loss in the first half of the 20th century was of the same order of magnitude as in the second half of the 20th century, even though the rate of warming was considerably smaller.
14
Dubnick, Ashley, Martin Sharp, Brad Danielson, Alireza Saidi-Mehrabad, and Joel Barker. "Basal thermal regime affects the biogeochemistry of subglacial systems." Biogeosciences 17, no. 4 (February 24, 2020): 963–77. http://dx.doi.org/10.5194/bg-17-963-2020.
Full textAbstract:
Abstract. Ice formed in the subglacial environment can contain some of the highest concentrations of solutes, nutrients, and microbes found in glacier systems, which can be released to downstream freshwater and marine ecosystems and glacier forefields. Despite the potential ecological importance of basal ice, our understanding of its spatial and temporal biogeochemical variability remains limited. We hypothesize that the basal thermal regime of glaciers is a dominant control on subglacial biogeochemistry because it influences the degree to which glaciers mobilize material from the underlying substrate and controls the nature and extent of biogeochemical activity that occurs at glacier beds. Here, we characterize the solutes, nutrients, and microbes found in the basal regions of a cold-based glacier and three polythermal glaciers and compare them to those found in overlying glacier ice of meteoric origin. Compared to meteoric glacier ice, basal ice from polythermal glaciers was consistently enriched in major ions, dissolved organic matter (including a specific fraction of humic-like fluorescent material), and microbes and was occasionally enriched in dissolved phosphorus and reduced nitrogen (NH4+) and in a second dissolved component of humic-like fluorescent material. In contrast, the biogeochemistry of basal ice from the cold-based glacier was remarkably similar to that of meteoric glacier ice. These findings suggest that a glacier's basal thermal regime can play an important role in determining the mix of solutes, nutrients, and microbes that are acquired from subglacial substrates or produced in situ.
15
McGrath, Daniel, Louis Sass, Shad O'Neel, Chris McNeil, Salvatore G. Candela, Emily H. Baker, and Hans-Peter Marshall. "Interannual snow accumulation variability on glaciers derived from repeat, spatially extensive ground-penetrating radar surveys." Cryosphere 12, no. 11 (November 22, 2018): 3617–33. http://dx.doi.org/10.5194/tc-12-3617-2018.
Full textAbstract:
Abstract. There is significant uncertainty regarding the spatiotemporal distribution of seasonal snow on glaciers, despite being a fundamental component of glacier mass balance. To address this knowledge gap, we collected repeat, spatially extensive high-frequency ground-penetrating radar (GPR) observations on two glaciers in Alaska during the spring of 5 consecutive years. GPR measurements showed steep snow water equivalent (SWE) elevation gradients at both sites; continental Gulkana Glacier's SWE gradient averaged 115 mm 100 m−1 and maritime Wolverine Glacier's gradient averaged 440 mm 100 m−1 (over > 1000 m). We extrapolated GPR point observations across the glacier surface using terrain parameters derived from digital elevation models as predictor variables in two statistical models (stepwise multivariable linear regression and regression trees). Elevation and proxies for wind redistribution had the greatest explanatory power, and exhibited relatively time-constant coefficients over the study period. Both statistical models yielded comparable estimates of glacier-wide average SWE (1 % average difference at Gulkana, 4 % average difference at Wolverine), although the spatial distributions produced by the models diverged in unsampled regions of the glacier, particularly at Wolverine. In total, six different methods for estimating the glacier-wide winter balance average agreed within ±11 %. We assessed interannual variability in the spatial pattern of snow accumulation predicted by the statistical models using two quantitative metrics. Both glaciers exhibited a high degree of temporal stability, with ∼85 % of the glacier area experiencing less than 25 % normalized absolute variability over this 5-year interval. We found SWE at a sparse network (3 stakes per glacier) of long-term glaciological stake sites to be highly correlated with the GPR-derived glacier-wide average. We estimate that interannual variability in the spatial pattern of winter SWE accumulation is only a small component (4 %–10 % of glacier-wide average) of the total mass balance uncertainty and thus, our findings support the concept that sparse stake networks effectively measure interannual variability in winter balance on glaciers, rather than some temporally varying spatial pattern of snow accumulation.
16
Gul, Rahman, Saad Khan, Siddique Ullah Baig, and Sidra Bibi. "Spatio-temporal Change in the Glaciers of Astore Basin (North-Western Himalaya), between 2016 and 2021 using Sentinel-2 Satellite Data." Journal Of The Geological Society Of India 100, no. 6 (June 1, 2024): 873–86. http://dx.doi.org/10.17491/jgsi/2024/173918.
Full textAbstract:
ABSTRACT About 2400 kilometers long Himalayan region hosts thousands of glaciers which covers about 40,000 km2 as per last update in September 2021. Estimation of snout variation positioning, statistical analysis of climate trends, and the Equilibrium Line Altitude (ELA) of most of the glaciers is challenging due to the rough terrain, higher altitudes and scarcity of spatio-temporal field observations. Moreover, without the climatic data and separating contour between glacier’s accumulation and ablation zones, estimation of the net variation in glacier mass loss or gain over a fixed year, leads to ambiguous results. Therefore, a quarterly trend analysis was carried out on climate data (temperature and precipitation ) and river discharge to evaluate the climate pattern in the Astore Basin. Moreover, this study uses the accumulation area ratio, AAR (0.6 ±0.5) (used for high-altitude mountain glaciers), and accumulation area balance ratio, AABR (2.24 ±0.9) with an interval of 0.05 and 0.01 to estimate ELAs, respectively. The results show that the Bazhin glacier retreat (-2.1 km²) as compared to the Chhongpher (-1.1 km²) and Chongra (-1.2 km²) glaciers. A maximum retreat of the snout position of Bazhin glacier was 1595 m , 3260 m in Chhongpher glacier, and 960 m in Chongra glacier. An increase in the ratio of annual AAR from 0.4 to 0.8 results in reductions of the accumulation area of three major glaciers in the study area. We conclude that the largest glaciers (e.g. Bazhin, Chhongpher and Chongra) stretched between lower to higher altitudes are likely to be more vulnerable, due to the highest AAR and AABR values reported between 5000-5600 meters above sea level (masl). However, the ice-lost estimates vary greatly depending on their three-dimensional surfaces.
17
Brugger, Keith A. "The non-synchronous response of Rabots Glaciär and Storglaciären, northern Sweden, to recent climate change: a comparative study." Annals of Glaciology 46 (2007): 275–82. http://dx.doi.org/10.3189/172756407782871369.
Full textAbstract:
AbstractRabots Glaciär and Storglaciären, two small valley glaciers in the Swedish Arctic, have not behaved synchronously in response to recent climate change. Both glaciers advanced late in the 19th century and then began to retreat in response to a ~1˚C warming that occurred around 1910. By the mid-1980s the terminus and volume of Storglaciären had essentially stabilized, so it may have completed its response to the earlier warming. In contrast, ongoing thinning and retreat of Rabots Glaciär are substantial and suggest its response time is considerably longer. A time-dependent numerical model was used to investigate each glacier’s response to perturbations in mass balance. This modeling suggests that, for small perturbations, volume timescales for Storglaciären and Rabots Glaciär are ~125 and ~215 years, respectively. Another measure of response time (i.e. length response time) yields somewhat lower values for each glacier; however, what is significant is that by either measure and accounting for uncertainties, the response time for Rabots Glaciär is consistently about 1.5 times longer than that for Storglaciären. This implies that their non-synchronous behavior is likely due to differences in response times. The latter ultimately result from markedly different longitudinal geometries (particularly near the termini), velocity profiles and specific net balance gradients.
18
Davidovich, N. V., and M. D. Ananicheva. "Prediction of possible changes in glacio-hydrological characteristics under global warming: southeastern Alaska, U.S.A." Journal of Glaciology 42, no. 142 (1996): 407–12. http://dx.doi.org/10.3189/s0022143000003397.
Full textAbstract:
AbstractWe use the Wetherald and Manabe climate model to predict the response of mountain glaciers to a doubling of atmospheric carbon dioxide. The response is measured in terms of a change in the equilibrium-line altitude (ELA) and the glacier terminus altitude (GTA), net accumulation–ablation on these altitudes and the melt runoff for 12 mountain-glacier regions in southeastern Alaska, U.S.A. The methods we use involve extrapolating climate-model temperature fields to a glacier’s location, and empirical–statistical relationships between air temperature and percentage of solid precipitation, and between summer air temperature and ablation and melt runoff. Our study shows that, under global warming, glaciation in southeastern Alaska will not disappear, but mass exchange of glaciers will be more intensive and the ELA value will increase by 300–760 m, depending on the glacier’s distance from the ocean.
19
Davidovich, N. V., and M. D. Ananicheva. "Prediction of possible changes in glacio-hydrological characteristics under global warming: southeastern Alaska, U.S.A." Journal of Glaciology 42, no. 142 (1996): 407–12. http://dx.doi.org/10.1017/s0022143000003397.
Full textAbstract:
Abstract We use the Wetherald and Manabe climate model to predict the response of mountain glaciers to a doubling of atmospheric carbon dioxide. The response is measured in terms of a change in the equilibrium-line altitude (ELA) and the glacier terminus altitude (GTA), net accumulation–ablation on these altitudes and the melt runoff for 12 mountain-glacier regions in southeastern Alaska, U.S.A. The methods we use involve extrapolating climate-model temperature fields to a glacier’s location, and empirical–statistical relationships between air temperature and percentage of solid precipitation, and between summer air temperature and ablation and melt runoff. Our study shows that, under global warming, glaciation in southeastern Alaska will not disappear, but mass exchange of glaciers will be more intensive and the ELA value will increase by 300–760 m, depending on the glacier’s distance from the ocean.
20
Rabatel, Antoine, Ana Bermejo, Edwin Loarte, Alvaro Soruco, Jesus Gomez, Gonzalo Leonardini, Christian Vincent, and Jean Emmanuel Sicart. "Can the snowline be used as an indicator of the equilibrium line and mass balance for glaciers in the outer tropics?" Journal of Glaciology 58, no. 212 (2012): 1027–36. http://dx.doi.org/10.3189/2012jog12j027.
Full textAbstract:
AbstractBecause the glacier snowline is easy to identify on optical satellite images and because in certain conditions it can be used as an indicator of the equilibrium line, it may be a relevant parameter for the study of the relationships between climate and glaciers. Although several studies have shown that the snowline altitude (SLA) at the end of the hydrological year is a good indicator of the equilibrium-line altitude (ELA) for mid-latitude glaciers, such a relationship remains conjectural for tropical glaciers. Indeed, unlike in mid-latitudes, tropical climate conditions result in a distinct seasonality of accumulation/ablation processes. We examine this relationship using direct field ELA and mass-balance measurements made on Glaciar Zongo, Bolivia (~16° S), vand Glaciar Artesonraju, Peru (~9° S), and the SLA retrieved from satellite images acquired in the past two decades. We show that on glaciers in the outer tropics: (1) ablation is reduced during the dry season in austral winter (May-August), the SLA does not change much, and satellite images acquired between May and August could be used to compute the SLA; and (2) the highest SLA detected on a number of satellite images acquired during the dry season provides a good estimate of the annual ELA. However, as snowfall events can occur during the dry season, the SLA detected on satellite images tends to underestimate the ELA. Thus, we recommend validating the SLA computed from satellite images with field data collected on a benchmark glacier before measuring the SLA on other glaciers in the same mountain range for which no field data are available. This study is a major step towards extending the measurement of glacier parameters (ELA and mass balance) at the scale of a whole mountain range in the outer tropics to better document the relationships between climate and glaciers.
21
Andersen, M. L., M. Nettles, P. Elosegui, T. B. Larsen, G. S. Hamilton, and L. A. Stearns. "Quantitative estimates of velocity sensitivity to surface melt variations at a large Greenland outlet glacier." Journal of Glaciology 57, no. 204 (2011): 609–20. http://dx.doi.org/10.3189/002214311797409785.
Full textAbstract:
AbstractThe flow speed of Greenland outlet glaciers is governed by several factors, the relative importance of which is poorly understood. The delivery of surface-generated meltwater to the bed of alpine glaciers has been shown to influence glacier flow speed when the volume of water is sufficient to increase basal fluid pressure and hence basal lubrication. While this effect has also been demonstrated on the Greenland ice-sheet margin, little is known about the influence of surface melting on the large, marine-terminating outlet glaciers that drain the ice sheet. We use a validated model of meltwater input and GPS-derived surface velocities to quantify the sensitivity of glacier flow speed to changes in surface melt at Helheim Glacier during two summer seasons (2007–08). Our observations span ∼55 days near the middle of each melt season. We find that relative changes in glacier speed due to meltwater input are small, with variations of ∼45% in melt producing changes in velocity of ∼2–4%. These velocity variations are, however, of similar absolute magnitude to those observed at smaller glaciers and on the ice-sheet margin. We find that the glacier’s sensitivity to variations in meltwater input decreases approximately exponentially with distance from the calving front. Sensitivity to melt varies with time, but generally increases as the melt season progresses. We interpret the time-varying sensitivity of glacier flow to meltwater input as resulting from changes in subglacial hydraulic routing caused by the changing volume of meltwater input.
22
Thomson, Laura I., Gordon R. Osinski, and C. Simon L. Ommanney. "Glacier change on Axel Heiberg Island, Nunavut, Canada." Journal of Glaciology 57, no. 206 (2011): 1079–86. http://dx.doi.org/10.3189/002214311798843287.
Full textAbstract:
AbstractHistorical records are valuable for assessing glacier change in the Canadian High Arctic. Ommanney’s (1969) detailed inventory of Axel Heiberg Island glaciers, based on photography from 1958–59, has been revisited, converted into digital format and compared to glacier extents mapped from 1999–2000 satellite imagery. Our results show that the island-wide ice coverage decreased by 15.92 km2 in the 42 year period, a loss of <1%. However, two trends are apparent: one of advance or minor retreat from basins hosting outlet glaciers from Müller and Steacie Ice Caps, and one of significant retreat, on the order of 50–80%, for independent ice masses, which include valley glaciers, mountain glaciers, glacierets, and ice caps smaller than 25 km2. If the contributions to ice advance of only three surging glaciers are removed, then the island-wide ice loss approaches 60 km2. Furthermore, it is notable that 90% of ice masses smaller than 0.2 km2 disappeared entirely during the 42 year study period, an observation confirmed by field studies. Successful predictions from the original inventory are highlighted and the likely mechanisms driving the observed advances and retreats are discussed.
23
Guo, Lei, Jia Li, Amaury Dehecq, Zhiwei Li, Xin Li, and Jianjun Zhu. "A new inventory of High Mountain Asia surging glaciers derived from multiple elevation datasets since the 1970s." Earth System Science Data 15, no. 7 (July 11, 2023): 2841–61. http://dx.doi.org/10.5194/essd-15-2841-2023.
Full textAbstract:
Abstract. Glacier surging is an unusual instability of ice flow, and inventories of surging glaciers are important for regional glacier mass balance studies and glacier dynamic studies. Glacier surges in High Mountain Asia (HMA) have been widely reported. However, the completeness of available inventories of HMA surging glaciers is hampered by the insufficient spatial and temporal coverage of glacier change observations or by the limitations of the identification methods. In this study, we established a new inventory of HMA surging glaciers based on glacier surface elevation changes and morphological changes over 4 decades. Three elevation change datasets based on four elevation sources (the KH-9 DEM, NASA DEM, COP30 DEM, and HMA DEM) and long-term Landsat satellite image series were utilized to assess the presence of typical surge features over two time periods (1970s–2000 and 2000–2020). A total of 890 surging and 336 probably or possibly surging glaciers were identified in HMA. Compared to the most recent inventory of surging glaciers in HMA, our inventory incorporated 253 previously unidentified surging glaciers. The number and area of surging glaciers accounted for ∼2.49 % (excluding glaciers smaller than 0.4 km2) and ∼16.59 % of the total glacier number and glacier area in HMA, respectively. Glacier surges were found in 21 of the 22 subregions of HMA (except for the Dzhungarsky Alatau); however, the density of surging glaciers is highly uneven. Glacier surges occur frequently in the northwestern subregions (e.g., Pamir and Karakoram) but less often in the peripheral subregions. The inventory further shows that surge activity is more likely to occur for glaciers with a larger area, longer length, and wider elevation range. Among glaciers with similar areas, the surging ones usually have steeper slopes than non-surging ones. The inventory and elevation change products of identified surging glaciers are available at https://doi.org/10.5281/zenodo.7961207 (Guo et al., 2023).
24
Zhao, Chuanxi, Zhen He, Shengyu Kang, Tianzhao Zhang, Yongjie Wang, Teng Li, Yifei He, and Wei Yang. "Contrasting Changes of Debris-Free Glacier and Debris-Covered Glacier in Southeastern Tibetan Plateau." Remote Sensing 16, no. 5 (March 5, 2024): 918. http://dx.doi.org/10.3390/rs16050918.
Full textAbstract:
Debris-free and debris-covered glaciers are both extensively present in the southeastern Tibetan Plateau. High-precision and rigorous comparative observational studies on different types of glaciers help us to accurately understand the overall state of water resource variability and the underlying mechanisms. In this study, we used multi-temporal simultaneous UAV surveys to systematically explore the surface elevation change, surface velocity, and surface mass balance of two representative glaciers. Our findings indicate that the thinning rate in the debris-free Parlung No. 4 glacier UAV survey area was consistently higher than that in the debris-covered 24K glacier in 2020–2021 (−1.16 ± 0.03 cm/d vs. −0.36 ± 0.02 cm/d) and 2021–2022 (−0.69 ± 0.03 cm/d vs. −0.26 ± 0.03 cm/d). Moreover, the surface velocity of the Parlung No. 4 glacier was also consistently higher than that of the 24K glacier across the survey period, suggesting a more dynamic glacial state. The surface mass balance of the Parlung No. 4 glacier (2020–2021: −1.82 ± 0.09 cm/d; 2021–2022: −1.30 ± 0.09 cm/d) likewise outpaced that of the 24K glacier (2020–2021: −0.81 ± 0.07 cm/d; 2021–2022: −0.70 ± 0.07 cm/d) throughout the observation period, which indicates that the debris cover slowed the glacier’s melting. Additionally, we extracted the melt contribution of the ice cliff area in the 24K glacier and found that the melt ratio of this ‘hotspot’ area ranged from 10.4% to 11.6% from 2020 to 2022. This comparative analysis of two representative glaciers provides evidence to support the critical role of debris cover in controlling surface elevation changes, glacier dynamics, and surface mass balance.
25
Stoyanov, Andrey. "APPLICATION OF SATELLITE DATA FOR MONITORING THE RETREAT OF MOUNTAIN GLACIER MORTERATSCH, SWISS ALPS, OVER A PERIOD OF 51 YEARS." Aerospace Research in Bulgaria 36 (2024): 107–14. http://dx.doi.org/10.3897/arb.v36.e09.
Full textAbstract:
The presented study aims to apply a method for monitoring the retreat of mountain glacier in Alpine region of Swiss Alps, which consists of using optical satellite imagery and their spectral capabilities to observe snow and ice objects on earth surface. Satellite imagery with its big legacy archive dating back to 1972 for Landsat imagery, can be of big help to track and monitor the alpine glaciers retreat for long periods and serve as a database for modelling and predicting the glaciers retreat in the future. By combining different satellite data processing approaches, results have been obtained on the spatial distribution and dynamics of the Morteratsch Glacier over a period of 51 years. The focus of the study is to track the changes that have occurred along the positions of the ice front (terminus) in glacier’s ablation zone to obtain information about glacier’s dynamics during the study period.
26
Enderlin, E. M., I. M. Howat, and A. Vieli. "The sensitivity of flowline models of tidewater glaciers to parameter uncertainty." Cryosphere Discussions 7, no. 3 (June 13, 2013): 2567–93. http://dx.doi.org/10.5194/tcd-7-2567-2013.
Full textAbstract:
Abstract. Depth-integrated (1-D) flowline models have been widely used to simulate fast-flowing tidewater glaciers and predict future change because their computational efficiency allows for continuous grounding line tracking, high horizontal resolution, and a physically-based calving criterion, which are all essential to realistic modeling of tidewater glaciers. As with all models, the values for parameters describing ice rheology and basal friction must be assumed and/or tuned based on observations. For prognostic studies, these parameters are typically tuned so that the glacier matches observed thickness and speeds at an initial state, to which a perturbation is applied. While it is well know that ice flow models are sensitive to these parameters, the sensitivity of tidewater glacier models has not been systematically investigated. Here we investigate the sensitivity of such flowline models of outlet glacier dynamics to uncertainty in three key parameters that influence a glacier's resistive stress components. We find that, within typical observational uncertainty, similar initial (i.e. steady-state) glacier configurations can be produced with substantially different combinations of parameter values, leading to differing transient responses after a perturbation is applied. In cases where the glacier is initially grounded near flotation across a basal overdeepening, as typically observed for rapidly changing glaciers, these differences can be dramatic owing to the threshold of stability imposed by the flotation criterion. The simulated transient response is particularly sensitive to the parameterization of ice rheology: differences in ice temperature of ∼ 2 °C can determine whether the glaciers thin to flotation and retreat unstably or remain grounded on a marine shoal. Due the highly non-linear dependence of tidewater glaciers on model parameters, we recommend that their predictions are accompanied by sensitivity tests that take parameter uncertainty into account.
27
Enderlin, E. M., I. M. Howat, and A. Vieli. "The sensitivity of flowline models of tidewater glaciers to parameter uncertainty." Cryosphere 7, no. 5 (October 7, 2013): 1579–90. http://dx.doi.org/10.5194/tc-7-1579-2013.
Full textAbstract:
Abstract. Depth-integrated (1-D) flowline models have been widely used to simulate fast-flowing tidewater glaciers and predict change because the continuous grounding line tracking, high horizontal resolution, and physically based calving criterion that are essential to realistic modeling of tidewater glaciers can easily be incorporated into the models while maintaining high computational efficiency. As with all models, the values for parameters describing ice rheology and basal friction must be assumed and/or tuned based on observations. For prognostic studies, these parameters are typically tuned so that the glacier matches observed thickness and speeds at an initial state, to which a perturbation is applied. While it is well know that ice flow models are sensitive to these parameters, the sensitivity of tidewater glacier models has not been systematically investigated. Here we investigate the sensitivity of such flowline models of outlet glacier dynamics to uncertainty in three key parameters that influence a glacier's resistive stress components. We find that, within typical observational uncertainty, similar initial (i.e., steady-state) glacier configurations can be produced with substantially different combinations of parameter values, leading to differing transient responses after a perturbation is applied. In cases where the glacier is initially grounded near flotation across a basal over-deepening, as typically observed for rapidly changing glaciers, these differences can be dramatic owing to the threshold of stability imposed by the flotation criterion. The simulated transient response is particularly sensitive to the parameterization of ice rheology: differences in ice temperature of ~ 2 °C can determine whether the glaciers thin to flotation and retreat unstably or remain grounded on a marine shoal. Due to the highly non-linear dependence of tidewater glaciers on model parameters, we recommend that their predictions are accompanied by sensitivity tests that take parameter uncertainty into account.
28
Fountain, Andrew G., Matthew J. Hoffman, Frank Granshaw, and Jon Riedel. "The ‘benchmark glacier’ concept – does it work? Lessons from the North Cascade Range, USA." Annals of Glaciology 50, no. 50 (2009): 163–68. http://dx.doi.org/10.3189/172756409787769690.
Full textAbstract:
AbstractBenchmark glaciers were established in many alpine areas during the 1960s as part of the International Hydrological Decade to represent ‘typical’ mass and energy processes on glaciers in different climatic regions around the world. These glaciers have received new interest in the past decade because they are used to infer the contribution of alpine glacier wastage to global sea-level rise. We compare South Cascade Glacier, the benchmark glacier for the northwest contiguous USA, and four other secondary glaciers, against the topographic, area and mass changes of 321 glaciers in the surrounding region. Results show that South Cascade Glacier is unusually large, of lower slope and much larger area and had mass losses greater than most other glaciers in the region. Three of the four secondary glaciers were much more typical. Year-to-year variations in mass balance were highly correlated between all five glaciers, and any of these glaciers, including the benchmark glacier, could be used to infer temporal mass variations in the region. However, the use of South Cascade Glacier to estimate area/mass losses for the region would result in overestimating the area/mass changes by a factor of three. Local differences in the magnitude of annual glacier mass balance control cumulative mass changes and area changes. There appears to be no way to select a representative glacier a priori, and knowledge of changes over the region is required. Therefore, there may be great uncertainty in estimates of sea-level rise from the wastage of alpine glaciers based on the benchmark approach. We recommend re-evaluation of regional glacier mass changes inferred from benchmark glaciers in critical regions.
29
DELL, REBECCA, RACHEL CARR, EMRYS PHILLIPS, and ANDREW J. RUSSELL. "Response of glacier flow and structure to proglacial lake development and climate at Fjallsjökull, south-east Iceland." Journal of Glaciology 65, no. 250 (March 13, 2019): 321–36. http://dx.doi.org/10.1017/jog.2019.18.
Full textAbstract:
ABSTRACTOver recent decades, the number of outlet glaciers terminating in lakes in Iceland has increased in line with climate warming. The mass-balance changes of these lake-terminating outlet glaciers are sensitive to rising air temperatures, due to altered glacier dynamics and increased surface melt. This study aims to better understand the relationship between proglacial lake development, climate, glacier dynamics and glacier structure at Fjallsjökull, a large, lake-terminating outlet glacier in south-east Iceland. We used satellite imagery to map glacier terminus position and lake extent between 1973 and 2016, and a combination of aerial and satellite imagery to map the structural architecture of the glacier's terminus in 1982, 1994 and 2011. The temporal evolution of ice surface velocities between 1990 and 2018 was calculated using feature tracking. Statistically significant increases in the rate of terminus retreat and lake expansion were identified in 2001, 2009 and 2011. Our surface velocity and structural datasets revealed the development of localised flow ‘corridors’ over time, which conveyed relatively faster flow towards the glacier's terminus. We attribute the overall changes in dynamics and structural architecture at Fjallsjökull to rising air temperatures, but argue that the spatial complexities are driven by glacier specific factors, such as basal topography.
30
Warren, Charles R., Andrés Rivera, and Austin Post. "Greatest Holocene advance of Glaciar Pio XI, Chilean Patagonia: possible causes." Annals of Glaciology 24 (1997): 11–15. http://dx.doi.org/10.3189/s026030550001185x.
Full textAbstract:
Glaciar Pio XI (or Glaciar Brüggen) may be the only glacier in the world currently at its Neoglacial maximum. During the 20th century, most glaciers in Patagonia have consistently retreated, whereas Glaciar Pio XI has advanced almost 10 km, most recently at rates of ≤ 1.5 m d−1. This advance cannot be explained with reference to climate alone. An explanatory model combining calving dynamics, sediment budget and fjord topography explains the main features of recent behaviour. This case-study exemplifies the climatically out-of-phase behaviour so typical of calving glaciers, and illustrates the spatial and temporal scale over which they may behave asynchronously in the southern Andes.
31
Warren, Charles R., Andrés Rivera, and Austin Post. "Greatest Holocene advance of Glaciar Pio XI, Chilean Patagonia: possible causes." Annals of Glaciology 24 (1997): 11–15. http://dx.doi.org/10.1017/s026030550001185x.
Full textAbstract:
Glaciar Pio XI (or Glaciar Brüggen) may be the only glacier in the world currently at its Neoglacial maximum. During the 20th century, most glaciers in Patagonia have consistently retreated, whereas Glaciar Pio XI has advanced almost 10 km, most recently at rates of ≤ 1.5 m d−1. This advance cannot be explained with reference to climate alone. An explanatory model combining calving dynamics, sediment budget and fjord topography explains the main features of recent behaviour. This case-study exemplifies the climatically out-of-phase behaviour so typical of calving glaciers, and illustrates the spatial and temporal scale over which they may behave asynchronously in the southern Andes.
32
Pelto, M. S. "Glacier annual balance measurement, forecasting and climate correlations, North Cascades, Washington 1984–2006." Cryosphere 2, no. 1 (January 25, 2008): 13–21. http://dx.doi.org/10.5194/tc-2-13-2008.
Full textAbstract:
Abstract. North Cascade glacier annual balance measured on 10 glaciers from 1984–2006 yielded mean annual balance (ba) of −0.54 m/a, and −12.38 m cumulatively. This is a significant loss for glaciers that average 30–60 m in thickness, 20–40% of their entire volume. Two observed glaciers, Lewis Glacier and Spider Glacier, no longer exist. The ba of North Cascade glaciers is reliably calculated, correlation coefficient 0.91, using 1 April snowpack water equivalent and ablation season temperature. Utilizing ba from 10 glaciers 1984–2006 and net balance (bn) from South Cascade 1960–2005, a set of forecast rules for glacier mass balance were derived utilizing October–April Pacific Decadal Oscillation and Multivariate El Nino Southern Oscillation index values. The forecast rules provide a correct assessment in 41 of the 46 years for South Cascade Glacier and 20 of 23 years for NCGCP glaciers. Glacier annual balance forecasting is an important step for summer water resource management in glacier runoff dominated stream systems. The forecast for North Cascade glaciers in 2007 is for a negative ba.
33
Rankl, M., C. Kienholz, and M. Braun. "Glacier changes in the Karakoram region mapped by multimission satellite imagery." Cryosphere 8, no. 3 (May 23, 2014): 977–89. http://dx.doi.org/10.5194/tc-8-977-2014.
Full textAbstract:
Abstract. Positive glacier-mass balances in the Karakoram region during the last decade have fostered stable and advancing glacier termini positions, while glaciers in the adjacent mountain ranges have been affected by glacier recession and thinning. In addition to fluctuations induced solely by climate, the Karakoram is known for a large number of surge-type glaciers. The present study provides an updated and extended inventory on advancing, stable, retreating, and surge-type glaciers using Landsat imagery from 1976 to 2012. Out of 1219 glaciers the vast majority showed a stable terminus (969) during the observation period. Sixty-five glaciers advanced, 93 glaciers retreated, and 101 surge-type glaciers were identified, of which 10 are new observations. The dimensional and topographic characteristics of each glacier class were calculated and analyzed. Ninety percent of nonsurge-type glaciers are shorter than 10 km, whereas surge-type glaciers are, in general, longer. We report short response times of glaciers in the Karakoram and suggest a shift from negative to balanced/positive mass budgets in the 1980s or 1990s. Additionally, we present glacier surface velocities derived from different SAR (synthetic aperture radar) sensors and different years for a Karakoram-wide coverage. High-resolution SAR data enables the investigation of small and relatively fast-flowing glaciers (e.g., up to 1.8 m day−1 during an active phase of a surge). The combination of multitemporal optical imagery and SAR-based surface velocities enables an improved, Karakoram-wide glacier inventory and hence, provides relevant new observational information on the current state of glaciers in the Karakoram.
34
Pelto, Mauri S. "Recent Terminus Behavior Of North Cascade Glaciers, Washington, Related To Climatic Sensitivity." Annals of Glaciology 14 (1990): 353. http://dx.doi.org/10.3189/s0260305500009277.
Full textAbstract:
Since 1977 ablation-season temperature has been 1.1°C above the 1930–80 mean and winter precipitation has been 14% below the 1930–80 mean. In order to identify the effect of this climatic fluctuation on North Cascade glaciers, the North Cascade Glacier-Climate Project has monitored the terminus behavior of 107 glaciers between 1983 and 1988.The 107 glaciers examined represent six climate sensitivity groups. Each group has a different sensitivity to the four primary climatic parameters: (1) ablation-season temperature, (2) accumulation-season precipitation, (3) summer cloud cover and (4) freezing levels during May and October precipitation events. A glacier’s sensitivity to each climatic parameter is determined by its geographic location and topographic position. Each sensitivity type has specific geographic and topographic characteristics, such as degree of radiational shading, orientation, altitude with respect to the local glaciation threshold, accumulation sources, and distance from the Cascade Crest. Accumulation sources are direct snowfall, wind drifting and avalanching.Of the 107 glaciers examined, 91 had retreated significantly between 1983 and 1988 and three had advanced. Correlation of retreat rate and climatic sensitivity type indicates that the higher a glacier’s winter balance, the smaller the retreat rate. High-altitude accumulation zones, multiple accumulation sources and a northward orientation are all associated with higher winter balances. Retreat was greatest for glaciers with poor radiational shading, and only direct snowfall accumulation. Retreat rate was slowest for glaciers with multiple accumulation sources and a northward orientation, though not necessarily good radiational shading. Retreat rate increased with distance east of the Cascade Crest and retreat rate was high for low-altitude glaciers.
35
Pelto, Mauri S. "Recent Terminus Behavior Of North Cascade Glaciers, Washington, Related To Climatic Sensitivity." Annals of Glaciology 14 (1990): 353. http://dx.doi.org/10.1017/s0260305500009277.
Full textAbstract:
Since 1977 ablation-season temperature has been 1.1°C above the 1930–80 mean and winter precipitation has been 14% below the 1930–80 mean. In order to identify the effect of this climatic fluctuation on North Cascade glaciers, the North Cascade Glacier-Climate Project has monitored the terminus behavior of 107 glaciers between 1983 and 1988. The 107 glaciers examined represent six climate sensitivity groups. Each group has a different sensitivity to the four primary climatic parameters: (1) ablation-season temperature, (2) accumulation-season precipitation, (3) summer cloud cover and (4) freezing levels during May and October precipitation events. A glacier’s sensitivity to each climatic parameter is determined by its geographic location and topographic position. Each sensitivity type has specific geographic and topographic characteristics, such as degree of radiational shading, orientation, altitude with respect to the local glaciation threshold, accumulation sources, and distance from the Cascade Crest. Accumulation sources are direct snowfall, wind drifting and avalanching. Of the 107 glaciers examined, 91 had retreated significantly between 1983 and 1988 and three had advanced. Correlation of retreat rate and climatic sensitivity type indicates that the higher a glacier’s winter balance, the smaller the retreat rate. High-altitude accumulation zones, multiple accumulation sources and a northward orientation are all associated with higher winter balances. Retreat was greatest for glaciers with poor radiational shading, and only direct snowfall accumulation. Retreat rate was slowest for glaciers with multiple accumulation sources and a northward orientation, though not necessarily good radiational shading. Retreat rate increased with distance east of the Cascade Crest and retreat rate was high for low-altitude glaciers.
36
BHATTACHARYA, ATANU, TOBIAS BOLCH, KRITI MUKHERJEE, TINO PIECZONKA, JAN KROPÁČEK, and 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, no. 236 (September 9, 2016): 1115–33. http://dx.doi.org/10.1017/jog.2016.96.
Full textAbstract:
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.
37
Błaszczyk, Małgorzata, Jacek A. Jania, and Leszek Kolondra. "Fluctuations of tidewater glaciers in Hornsund Fjord (Southern Svalbard) since the beginning of the 20th century." Polish Polar Research 34, no. 4 (December 1, 2013): 327–52. http://dx.doi.org/10.2478/popore-2013-0024.
Full textAbstract:
Abstract Significant retreat of glaciers terminating in Hornsund Fjord (Southern Spits− bergen, Svalbard) has been observed during the 20th century and in the first decade of the 21st century. The objective of this paper is to present, as complete as possible, a record of front positions changes of 14 tidewater glaciers during this period and to distinguish the main factors influencing their fluctuations. Results are based on a GIS analysis of archival maps, field measurements, and aerial and satellite images. Accuracy was based on an as− sessment of seasonal fluctuations of a glacier’s ice cliff position with respect to its mini− mum length in winter (November-December) and its maximum advance position in June or July.Morphometric features and the environmental setting of each glacier are also pre− sented. The total area of the glacier cover in Hornsund Fjord in the period of 1899-2010 diminished approximately 172 km2, with an average areal retreat rate of 1.6 km2a−1. The recession rate increased from ~1 km2a−1 in first decades of the 20th century up to ~3 km2a−1 in years 2001-2010. The latest period was more thoroughly studied using optical satellite images acquired almost every year. The importance of glacier morphology and hypspmetry, as well as fjord bathymetry and topography is analyzed. Large glacier systemswith low slopes terminating in deeper waters are retreating faster than small steep glaciers ter− minating in shallower water. A relation between mean annual air temperature and aerial retreat rate of tidewater glaciers was found for long time scales. A sudden temperature in− crease, known as the early 20th century warming in Svalbard, and an increase in temperatures during recent decades are well reflected in deglaciation rate. Influence of sea water temperatures on calving and retreat of glaciers was considered and is significant in short−time intervals of the last decade. Surge events are non−climatic factors which com− plicate the record. They are reflected in front advance or fast retreat due to a massive calving depending on the relation between ice thickness and water depth. Despite the influence of many factors, the response of tidewater glaciers to climate change is evident. The average linear retreat rate of all the tidewater glaciers in Hornsund amounted to ~70 ma−1 in 2001-2010 and was higher than the average retreat of other Svalbard tidewater glaciers (~45 ma−1). Thus, glaciers of this basin can be considered as more sensitive to climate than glaciers of other regions of the archipelago.
38
Stumm, Dorothea, Sharad Prasad Joshi, Tika Ram Gurung, and Gunjan Silwal. "Mass balances of Yala and Rikha Samba glaciers, Nepal, from 2000 to 2017." Earth System Science Data 13, no. 8 (August 6, 2021): 3791–818. http://dx.doi.org/10.5194/essd-13-3791-2021.
Full textAbstract:
Abstract. The glacier mass balance is an important variable to describe the climate system and is used for various applications like water resource management or runoff modelling. The direct or glaciological method and the geodetic method are the standard methods to quantify glacier mass changes, and both methods are an integral part of international glacier monitoring strategies. In 2011, we established two glacier mass-balance programmes on Yala and Rikha Samba glaciers in the Nepal Himalaya. Here we present the methods and data of the directly measured annual mass balances for the first six mass-balance years for both glaciers from 2011/2012 to 2016/2017. For Yala Glacier we additionally present the directly measured seasonal mass balance from 2011 to 2017, as well as the mass balance from 2000 to 2012 obtained with the geodetic method. In addition, we analysed glacier length changes for both glaciers. The directly measured average annual mass-balance rates of Yala and Rikha Samba glaciers are −0.80 ± 0.28 and −0.39 ± 0.32 m w.e. a−1, respectively, from 2011 to 2017. The geodetically measured annual mass-balance rate of Yala Glacier based on digital elevation models from 2000 and 2012 is −0.74 ± 0.53 m w.e. The cumulative mass loss for the period 2011 to 2017 for Yala and Rikha Samba glaciers is −4.80 ± 0.69 and −2.34 ± 0.79 m w.e., respectively. The mass loss on Yala Glacier from 2000 to 2012 is −8.92 ± 6.33 m w.e. The winter balance of Yala Glacier is positive, and the summer balance is negative in every investigated year. The summer balance determines the annual balance. Compared to regional mean geodetic mass-balance rates in the Nepalese Himalaya, the mean mass-balance rate of Rikha Samba Glacier is in a similar range, and the mean mass-balance rate of Yala Glacier is more negative because of the small and low-lying accumulation area. During the study period, a change of Yala Glacier's surface topography has been observed with glacier thinning and downwasting. The retreat rates of Rikha Samba Glacier are higher than for Yala Glacier. From 1989 to 2013, Rikha Samba Glacier retreated 431 m (−18.0 m a−1), and from 1974 to 2016 Yala Glacier retreated 346 m (−8.2 m a−1). The data of the annual and seasonal mass balances, point mass balance, geodetic mass balance, and length changes are accessible from the World Glacier Monitoring Service (WGMS, 2021), https://doi.org/10.5904/wgms-fog-2021-05.
39
Turrin, J. B., and R. R. Forster. "A conceptual model of cyclical glacier flow in overdeepenings." Cryosphere Discussions 8, no. 4 (August 12, 2014): 4463–95. http://dx.doi.org/10.5194/tcd-8-4463-2014.
Full textAbstract:
Abstract. A nearly four-decade, satellite-based velocity survey of the largest glaciers in the Alaska Range, Chugach Mountains, and the Wrangell Mountains of southern Alaska, spanning the early- to mid-1970s through the 2000s, reveals nine pulsing glaciers: Capps, Copper, Eldridge, Kahiltna, Matanuska, Nabesna, Nizina, Ruth, and Sanford glaciers. The pulses increase velocity by up to 2449% (Capps Glacier) or as little as 77% (Nabesna Glacier), with velocity increases for the other glaciers in the range of 100–250%. The pulses may last from between six years (Copper Glacier) to 12 years (Nizina Glacier) and consist of a multi-year acceleration phase followed by a multi-year deceleration phase during which significant portions of each glacier move en masse. The segments of each glacier affected by the pulses may be anywhere from 14 km (Sanford Glacier) to 36 km (Nabesna Glacier) in length and occur where the glaciers are either laterally constricted or joined by a major tributary, and the surface slopes at these locations are very shallow, 1–2°, suggesting the pulses occur where the glaciers are overdeepened. A conceptual model to explain the cyclical behavior of these pulsing glaciers is presented that incorporates the effects of glaciohydraulic supercooling, glacier dynamics, surface ablation, and subglacial sediment erosion, deposition, and deformation in overdeepenings.
40
Guillet, Gregoire, Owen King, Mingyang Lv, Sajid Ghuffar, Douglas Benn, Duncan Quincey, and Tobias Bolch. "A regionally resolved inventory of High Mountain Asia surge-type glaciers, derived from a multi-factor remote sensing approach." Cryosphere 16, no. 2 (February 18, 2022): 603–23. http://dx.doi.org/10.5194/tc-16-603-2022.
Full textAbstract:
Abstract. Knowledge about the occurrence and characteristics of surge-type glaciers is crucial due to the impact of surging on glacier melt and glacier-related hazards. One of the super-clusters of surge-type glaciers is High Mountain Asia (HMA). However, no consistent region-wide inventory of surge-type glaciers in HMA exists. We present a regionally resolved inventory of surge-type glaciers based on their behaviour across High Mountain Asia between 2000 and 2018. We identify surge-type behaviour from surface velocity, elevation and feature change patterns using a multi-factor remote sensing approach that combines yearly ITS_LIVE velocity data, DEM differences and very-high-resolution imagery (Bing Maps, Google Earth). Out of the ≈95 000 glaciers in HMA, we identified 666 that show diagnostic surge-type glacier behaviour between 2000 and 2018, which are mainly found in the Karakoram (223) and the Pamir regions (223). The total area covered by the 666 surge-type glaciers represents 19.5 % of the glacierized area in Randolph Glacier Inventory (RGI) V6.0 polygons in HMA. Only 68 glaciers were already identified as “surge type” in the RGI V6.0. We further validate 107 glaciers previously labelled as “probably surge type” and newly identify 491 glaciers, not previously reported in other inventories covering HMA. We finally discuss the possibility of self-organized criticality in glacier surges. Across all regions of HMA, the surge-affected area within glacier complexes displays a significant power law dependency with glacier length.
41
Bown, Francisca, Andrés Rivera, and César Acuña. "Recent glacier variations at the Aconcagua basin, central Chilean Andes." Annals of Glaciology 48 (2008): 43–48. http://dx.doi.org/10.3189/172756408784700572.
Full textAbstract:
AbstractThe majority of glaciers in central Chile have receded in recent decades, from >50m to only a few meters per year, mainly in response to an increase in the 0˚C isotherm altitude. The Aconcagua river basin (33˚ S) is one of the major glaciated basins in central Chile, with 121 km2 of ice in 2003. An earlier inventory using 1955 aerial photographs yielded a total surface area of 151 km2, implying a reduction in glacier area of 20% (0.63km2 a–1) over the 48 years. Photographic stereo models, high-resolution satellite images (Landsat, ASTER) and SRTM data have been used to delineate glacier basins. A focus on Glaciar Juncal Norte, one of the largest glaciers in the basin, allows a more detailed analysis of changes. The glacier has exhibited a smaller reduction (14%) between 1955 and 2006, and the resulting elevation changes over this smaller period are not significant. The above reduction rates are lower than in other glaciers of central Chile and Argentina. This trend emphasizes water runoff availability in a river where most of the water in the dry summers is generated by glaciers and snowpack, and where most of the superficial water rights are already allocated. Ongoing hydrological research including modelling of future water runoff will improve our understanding.
42
Ramírez, Edson, Bernard Francou, Pierre Ribstein, Marc Descloitres, Roger Guérin, Javier Mendoza, Robert Gallaire, Bernard Pouyaud, and Ekkehard Jordan. "Small glaciers disappearing in the tropical Andes: a case-study in Bolivia: Glaciar Chacaltaya (16o S)." Journal of Glaciology 47, no. 157 (2001): 187–94. http://dx.doi.org/10.3189/172756501781832214.
Full textAbstract:
AbstractGlaciar Chacaltaya is an easily accessible glacier located close to La Paz, Bolivia. Since 1991, information has been collected about the evolution of this glacier since the Little Ice Age, with a focus on the last six decades. The data considered in this study are monthly mass-balance measurements, yearly mappings of the surface topography and a map of the glacier bed given by ground-penetrating radar survey. A drastic shrinkage of ice has been observed since the early 1980s, with a mean deficit about 1 m a−1 w.e. From 1992 to 1998, the glacier lost 40% of its average thickness and two-thirds of its total volume, and the surface area was reduced by >40%. With a mean estimated equilibrium-line altitude lying above its upper reach, the glacier has been continuously exposed to a dominant ablation on the whole surface area. If the recent climatic conditions continue, a complete extinction of this glacier in the next 15 years can be expected. Glaciar Chacaltaya is representative of the glaciers of the Bolivian eastern cordilleras, 80% of which are small glaciers (<0.5 km2). A probable extinction of these glaciers in the near future could seriously affect the hydrological regime and the water resources of the high-elevation basins.
43
Zhang, Xueying, Lin Liu, Zhengyong Zhang, Ziwei Kang, Hao Tian, Tongxia Wang, and Hongjin Chen. "Spatial and Temporal Variation Characteristics of Glacier Resources in Xinjiang over the Past 50 Years." Water 14, no. 7 (March 28, 2022): 1057. http://dx.doi.org/10.3390/w14071057.
Full textAbstract:
Changes in glacier resources and their meltwater runoff contributions in Xinjiang are significant to the hydrological processes and water resources utilization. This study used the first and second Chinese Glacier Inventory, geomorphological and meteorological data. GIS spatial analysis technology was used to explore the characteristics of glacier change and its response to topography and climate change in Xinjiang in the last 50 years. The results show that there are currently 20,695 glaciers in Xinjiang with a total area of 22,742.55 km2 and ice reserves of about 2229.17 km3. Glaciers in Xinjiang are concentrated at 5100–6000 m. The Tianshan mountains have the largest number of glaciers. However, the Kunlun mountains have the largest glaciers and ice reserves. The scale of glaciers is significantly larger in the south than that in the north. The changes in glaciers in Xinjiang during the last 50 years are mainly receding and splitting, and their number, area, and ice reserves have decreased by 1359, 7080.12 km2 and 482.65 km3, respectively. Small glaciers are more sensitive to climate change. Glaciers are basically unchanged in regions above 6000 m. The glaciers on the south slope of mountains are more susceptible to climate change. The phenomenon of an increase in the number of glaciers but decreasing total area in the southern mountains is related to glacier extinction and splitting. Glacier development and formation are determined by the combination of topography and hydrothermal material conditions. The change of glacier areas in Xinjiang is jointly affected by climatic conditions (53.45%) and topographic conditions (46.55%), among which climatic conditions are more prominent.
44
Zhao, Chuanxi, Wei Yang, Evan Miles, Matthew Westoby, Marin Kneib, Yongjie Wang, Zhen He, and Francesca Pellicciotti. "Thinning and surface mass balance patterns of two neighbouring debris-covered glaciers in the southeastern Tibetan Plateau." Cryosphere 17, no. 9 (September 12, 2023): 3895–913. http://dx.doi.org/10.5194/tc-17-3895-2023.
Full textAbstract:
Abstract. Debris-covered glaciers are a common feature of the mountain cryosphere in the southeastern Tibetan Plateau. A better understanding of these glaciers is necessary to reduce the uncertainties in regional water resource variability and to anticipate potential cryospheric risks. In this study, we quantified the seasonal thinning and surface mass balance patterns of two neighbouring debris-covered glaciers (23K Glacier and 24K Glacier) in the southeastern Tibetan Plateau with four unpiloted aerial vehicle surveys and in situ measurements. We observed that the thinning of 23K Glacier was ∼2–7 times greater than that of the 24K Glacier for annual and cold periods. The surface velocity of the 24K Glacier is higher than that of the 23K Glacier (∼5–6 times) for all periods. In contrast with the thinning patterns, the surface mass balance patterns of the two glaciers closely agree across the different periods. We found that the surface mass balance distribution strongly correlated with the spatial distribution of debris thickness for both glaciers. Ice cliffs and supraglacial ponds are prevalent on the surface of these glaciers (∼4.4–7.2±0.5 %) and enhance melt overall (enhancement factor: ∼2.5) but do not control the surface mass balance pattern of either glacier. This comparison study of two neighbouring glaciers confirms the significance of both glacier dynamics and debris thickness in controlling thinning and melt for the different debris-covered glaciers of the southeastern Tibetan Plateau in the context of climate change.
45
Hoffman, Matthew J., Andrew G. Fountain, and Jonathan M. Achuff. "20th-century variations in area of cirque glaciers and glacierets, Rocky Mountain National Park, Rocky Mountains, Colorado, USA." Annals of Glaciology 46 (2007): 349–54. http://dx.doi.org/10.3189/172756407782871233.
Full textAbstract:
AbstractComparison of historic maps and aerial and ground-based photographs for the small cirque glaciers and glacierets of Rocky Mountain National Park in the northern Front Range of Colorado, USA, indicates modest change during the 20th century. The glaciers retreated through the first half of the 20th century, advanced slightly from the mid-1940s to the end of the century and have retreated slightly since. High interannual variability in area and temporal gaps in data complicate the trends. Local climate records indicate a lack of systematic change between 1950 and 1975, but significant warming afterwards. Local topographic effects (e.g. wind redistribution of snow and avalanching) are important influences. These small glaciers respond to changes in regional climate; summer temperature alone is a good predictor of the mass balance of Andrews Glacier (r= -0.93). Spring snowfall is also an important factor. That winter precipitation is not statistically significant supports the notion that these small glaciers gain much snow from wind drift and avalanching, making winter snow accumulation almost indifferent to variations in direct snowfall. Less than expected glacier retreat may be due to increased summer cloudiness.
46
Granshaw, Frank D., and Andrew G. Fountain. "Glacier change (1958–1998) in the North Cascades National Park Complex, Washington, USA." Journal of Glaciology 52, no. 177 (2006): 251–56. http://dx.doi.org/10.3189/172756506781828782.
Full textAbstract:
AbstractThe spatial characteristics for all glaciers in the North Cascades National Park Complex, USA, were estimated in 1958 and again in 1998. The total glacier area in 1958 was 117.3 ± 1.1 km2; by 1998 the glacier area had decreased to 109.1 ± 1.1 km2, a reduction of 8.2 ± 0.1 km2 (7%). Estimated volume loss during the 40 year period was 0.8 ± 0.1 km3 of ice. This volume loss contributes up to 6% of the August–September stream-flow and equals 16% of the August–September precipitation. No significant correlations were found between magnitude of glacier shrinkage and topographic characteristics of elevation, aspect or slope. However, the smaller glaciers lost proportionally more area than the larger glaciers and had a greater variability in fractional change than larger glaciers. Most of the well-studied alpine glaciers are much larger than the population median, so global estimates of glacier shrinkage, based on these well-studied glaciers, probably underestimate the true magnitude of regional glacier change.
47
Banerjee, Argha. "Volume-area scaling for debris-covered glaciers." Journal of Glaciology 66, no. 259 (August 18, 2020): 880–86. http://dx.doi.org/10.1017/jog.2020.69.
Full textAbstract:
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.
48
Capps, Denny M. "The role of glaciers and glacier research in the development of U. S. national parks." Earth Sciences History 36, no. 2 (January 1, 2017): 337–58. http://dx.doi.org/10.17704/1944-6178-36.2.337.
Full textAbstract:
ABSTRACT U.S. national parks and glacier research are inextricably linked. They are also an integral part of our history and cultural identity. For example, John Muir studied glaciers at Yosemite, Glacier Bay, and other future park areas. He measured glacier movement and recognized signs of past glaciations. Most U.S. glacier research now occurs in national parks due to the areas that they protect. Of the approximately 75,000 km2 of glacier coverage in the U.S., only 683 km2 lies outside of Alaska. Glaciers covering an area of 43,745 km2 are wholly or partly enclosed within nine Alaskan parks. 29,041 km2 occur in Wrangell-St. Elias alone. The relationship of national parks and glaciers is not mere chance. As Robert Sterling Yard said, “Geology is the anatomy of scenery”. Glaciers are responsible for the scenery and habitat of many national parks from Glacier to Glacier Bay. Here, I highlight past contributions from glacier researchers in national parks and how glaciers have shaped the foundations of many national parks.
49
Church, Gregory, Andreas Bauder, Melchior Grab, and Hansruedi Maurer. "Ground-penetrating radar imaging reveals glacier's drainage network in 3D." Cryosphere 15, no. 8 (August 23, 2021): 3975–88. http://dx.doi.org/10.5194/tc-15-3975-2021.
Full textAbstract:
Abstract. Hydrological systems of glaciers have a direct impact on the glacier dynamics. Since the 1950s, geophysical studies have provided insights into these hydrological systems. Unfortunately, such studies were predominantly conducted using 2D acquisitions along a few profiles, thus failing to provide spatially unaliased 3D images of englacial and subglacial water pathways. The latter has likely resulted in flawed constraints for the hydrological modelling of glacier drainage networks. Here, we present 3D ground-penetrating radar (GPR) results that provide high-resolution 3D images of an alpine glacier's drainage network. Our results confirm a long-standing englacial hydrology theory stating that englacial conduits flow around glacial overdeepenings rather than directly over the overdeepening. Furthermore, these results also show exciting new opportunities for high-resolution 3D GPR studies of glaciers.
50
Bhambri, R., T. Bolch, P. Kawishwar, D. P. Dobhal, D. Srivastava, and B. Pratap. "Heterogeneity in Glacier response from 1973 to 2011 in the Shyok valley, Karakoram, India." Cryosphere Discussions 6, no. 4 (July 31, 2012): 3049–78. http://dx.doi.org/10.5194/tcd-6-3049-2012.
Full textAbstract:
Abstract. A glacier inventory for the Shyok and Chang Chenmo basins was generated for the year 2002 using semi-automated methods based on Landsat ETM+ and SRTM3 DEM data. Glacier change analysis was carried out for 134 glaciers based on Hexagon KH-9 (years 1973, 1974) and Landsat TM/ETM+ (1989, 2002 and 2011) images. The 2002 inventory contains 2123 glaciers with an area of 2977.9±92.2 km2 in the entire study area including Shyok (1605 glaciers; area 2499±77.4 km2) and Chang Chenmo basins (518 glaciers; area 478.7±14.8 km2). Out of 2123 glaciers, only eight glaciers have higher elevation ranges than 2000 m. On average, the glacier area in Chang Chenmo basin exhibited no changes during the study period. However, individual absolute glacier area changes varied from −0.7±0.03 km2 to +0.2±0.01 km2 between 1973 and 2011. 10 glaciers exhibited an area increase of 1.7±0.07 km2 in total while 36 glaciers lost about total 1.8±0.07 km2. The glacier area decreased by 11±0.47 km2 from 1973 to 1989 in the Shyok basin whereas an increase in area of 8.2±0.33 km2 was observed during 1989–2002. The area has further increased by 5.6±0.21 km2 from 2002 to 2011 in the respective basin. This individual glacier response heterogeneity can be attributed to surging and possibly due to decreased temperature in last decades. However, further detailed studies are needed to understand glacier surge mechanism and the possible mass gain.