Perennial Snowfields Research Articles

Wind-tunnel measurements of sensible turbulent heat fluxes over melting ice

Accelerated glacier melt and the loss of perennial snowfields have been associated with increased warming in polar regions, at rates up to four times faster than the rest of the world, thereby reinforcing the critical need for improved models (and predictions) of glacier melt. An essential requirement for such models is an improved understanding of the sensible heat fluxes over glaciers. Since their complexity makes them difficult to model, and direct measurements of sensible turbulent heat fluxes over real glaciers are both rare and impractical, the present work involves simultaneous hot-wire anemometry and cold-wire thermometry measurements of two components of velocity and temperature above a melting glacier model in a series of wind-tunnel experiments. Both single- and multi-variable statistics were used to compare the turbulent velocity field measured over melting ice with that of a similar flow in the absence of ice. The results demonstrate that the ice's presence reduces the magnitude of the Reynolds stresses and vertical velocity variance, but also increases the streamwise velocity variance. The transient evolution of temperature statistics throughout the melt process was also investigated and found to be similar when suitably non-dimensionalized. The velocity and temperature fields were furthermore evaluated at an equivalent non-dimensional time during the melt process, in which statistics of the temperature field, and joint statistics of the vertical velocity and temperature, were studied. The present work lays the foundation for future laboratory-scale replications of the flow above melting glaciers, and provides additional insight into turbulent heat transfer over melting ice.

Inventory of glaciers and perennial snowfields of the conterminous USA

Abstract. This report summarizes an updated inventory of glaciers and perennial snowfields of the conterminous United States. The inventory is based on interpretation of mostly aerial imagery provided by the National Agricultural I magery Program, US Department of Agriculture, with some satellite imagery in places where aerial imagery was not suitable. The inventory includes all perennial snow and ice features ≥ 0.01 km2. Due to aerial survey schedules and seasonal snow cover, imageries acquired over a number of years were required. The earliest date is 2013 and the latest is 2020, but more than 73 % of the outlines were acquired from 2015 imagery. The inventory is compiled as shapefiles within a geographic information system that includes feature classification, area, and location. The inventory identified 1331 (366.52 ± 14.34 km2) glaciers, 1176 (31.01 ± 9.30 km2) perennial snowfields, and 35 (3.57 km2 ± no uncertainty) buried-ice features. The data including both the shapefiles and tabulated results are publicly available at https://doi.org/10.15760/geology-data.03 (Fountain and Glenn, 2022).

Сравнительная динамика отдельных ледников массива Мунку-Сардык (Восточный Саян) и хребта Цаст-Ула (Монгольский Алтай)

Continuing the study of modern glaciation on the example of individual mountain ranges of the inland part of Asia along the latitudinal transect from the Kodar Mountains to the Himalayas, this work considers the Tzast-Ula massif in the Mongolian Altai. These glaciers, as objects of the transect, represent its western part. The glaciers of northwestern Mongolia are studied by glaciologists, although not as detailed as the glaciers of the central part of Altai and the Tien Shan. It is interesting to consider their dynamics in comparison with other glacial massifs of the transect. In the Eastern Sayan, the most studied (more than 100 years) are the nival-glacial objects of the Munku-Sardyk range. In this paper, changes in glaciers at the main peaks of the Munku-Sardyk mountain range and the Tzast-Ula ridge are considered. Throughout the transect there is a reduction in glaciers and an increase in the intensity of armor by surface moraines. Moraine reservation of the lower part of the small glaciers of Tzast-Ula occurs, similar to the glaciers of Munku-Sardyk. According to the remote sensing data (Landsat), a comparison of the dynamics of both the entire massif and individual glaciers No. 7, 8 Tzast-Ula and glaciers No. 31 (Peretolchina) and No. 30 (Radde) was made, which shows that glaciers are shrinking to varying degrees. Since the mid-1970s, Glacier No. 7 has shrunk in area by 19 %, in length by about 5 %, No. 8 by 58 % and 31 %, respectively. The decrease in the area of the entire Tsambaragav massif on average took place at a speed of 0.31 km2/year. The glaciers of Tzast-Ula were shrinking unevenly at an average speed of 0.32 km2/year, losing 22 % of their area. The glaciers of the Munku-Sardyk massif are shrinking about 4 times slower. Over the past 20 years, the Peretolchina glacier has been shrinking in area at a rate of 0.005 km2/year, and for the entire observation period since 1900—0.004 km2/year. In length, during the same period, the glacier was shrinking at a rate of 5 m/year. The open part of the Peretolchina glacier from the final moraine of the end stage of the Little Ice Age decreased both in area and length by about half. Anomalous changes were detected in the glaciers under consideration in 2013–2015, both for the Tzast-Ula ridge and for Munku-Sardyk. By 2013–2014, there was an increase in the area of the open part of glaciers and the area of perennial snowfields and a sharp decrease after 2015, in some cases in the form of a descent of parts of glaciers.

Glaciers of the Olympic Mountains, Washington—The Past and Future 100 Years

AbstractIn 2015, the Olympic Mountains contained 255 glaciers and perennial snowfields totaling 25.34 ± 0.27 km2, half of the area in 1900, and about 0.75 ± 0.19 km3 of ice. Since 1980, glaciers shrank at a rate of −0.59 km2 yr−1 during which time 35 glaciers and 16 perennial snowfields disappeared. Area changes of Blue Glacier, the largest glacier in the study region, was a good proxy for glacier change of the entire region. Modeled glacier mass balance, based on monthly air temperature and precipitation, correlates with glacier area change. The mass balance is highly sensitive to changes in air temperature rather than precipitation, typical of maritime glaciers. In addition to increasing summer melt, warmer winter temperatures changed the phase of precipitation from snow to rain, reducing snow accumulation. Changes in glacier mass balance are highly correlated with the Pacific North American index, a proxy for atmospheric circulation patterns and controls air temperatures along the Pacific Coast of North America. Regime shifts of sea surface temperatures in the North Pacific, reflected in the Pacific Decadal Oscillation (PDO), trigger shifts in the trend of glacier mass balance. Negative (“cool”) phases of the PDO are associated with glacier stability or slight mass gain whereas positive (“warm”) phases are associated with mass loss and glacier retreat. Over the past century the overall retreat is due to warming air temperatures, +0.7°C in winter and +0.3°C in summer. The glaciers in the Olympic Mountains are expected to largely disappear by 2070.

Mass balance of two perennial snowfields: Niwot Ridge, Colorado, and the Ulaan Taiga, Mongolia

ABSTRACT Perennial snowfields are generally receding worldwide, though the precise mechanisms causing recessions are not always well understood. Here we apply a numerical snowpack model to identify the leading factors controlling the mass balance of two perennial snowfields that have significant human interest: Arapaho Glacier, located at Niwot Ridge in the Colorado Rocky Mountains (United States), and a snowfield located in the Ulaan Taiga (Mongolia). The two locations were chosen because they differ in elevation, slope, and aspect. However, both have subarctic climates and are located within semi-arid regions. We show that for these two locations the snowfield mass balance is primarily sensitive to air temperature and wind speed, followed by precipitation and dust deposition amounts. The lack of sensitivity to dust deposition was most likely due to timing of deposition and the overall small dust amounts. We find that the sensitivities are similar for the center of the snowfield as well as the margins.

Formation factors of surface inflow to antarctic lakes of the Larsemann Hills oasis

The study aims to identify formation factors of water inflow to the Antarctic lakes of the Larsemann Hills oasis (East Antarctica). The objects of study are 11 lakes of the oasis. The analysis was performed based on the expeditionary data of the Russian Antarctic Expedition (RAE): 63rd season (23 December 2017 – 3 February 2018), 64th season (12 January 2019 – 27 February 2019), 65th season (2 November 2019 – 24 March 2020). Data of lakes water level observations, aerial photography of the unmanned aerial vehicle (UAV) and route surveys are given, the results of identifying the boundaries of the lakes catchments are presented. The factors that determine the formation of water inflow to the lakes in this region were identified based on the analysis of the materials. The most significant are the meteorological conditions, the presence of perennial snowfields and glacial areas in the catchments, and the presence of lakes that can cause outburst flood. The seasonally thawed layer also has an impact on the formation of the inflow to the lakes. The vegetation cover is not so important for inflow formation in this region due to the physical and geographical conditions. As for anthropogenic activity, it mainly affects the environmental situation of the catchments and water quality, while the anthropogenic influence on the formation of water inflow to the lakes in the oasis is limited to the territories of polar stations. The factors identified should be taken into account in the further study of hydrological processes, the creation of models that describe them, and the organization of field observations.

Headwaters Fed by Subterranean Ice: Potential Climate Refugia for Mountain Stream Communities?

Near-term extirpations of macroinvertebrates are predicted for mountain streams worldwide as a warming climate drives the recession of high-elevation ice and snow. However, hydrological sources likely vary in their resistance to climate change, and thus streams fed by more resistant sources could persist as climate refugia for imperiled biota. In 2015–2016, we measured habitat characteristics and quantified macroinvertebrate community structure along 6 alpine streams in the Teton Range, Wyoming, USA. Strong differences in habitat characteristics (e.g., temperature, bed stability, conductivity) confirmed 3 major stream sources: surface glaciers, perennial snowfields, and subterranean ice. Subterranean ice-fed streams—termed “icy seeps”—appear common in the Teton Range and elsewhere, yet are globally understudied. Midges in the family Chironomidae dominated our study sites, representing 78.6% of all specimens sampled, with nematodes, caddisflies (Neothremma), and mayflies (Epeorus) also common. At the community scale, glacier- and snowmelt-fed streams differed significantly in multivariate space, with icy-seep communities intermediate between them, incorporating components of both assemblages. Because the thermal environment of subterranean ice, including rock glaciers, is decoupled from large-scale climatic conditions, we predict that icy seeps will remain intact longer than streams fed by surface ice and snow. Furthermore, our results suggest that icy seeps are suitable habitat for many macroinvertebrates occupying streams fed by vulnerable hydrological sources. Thus, icy seeps may act as key climate refugia for mountain stream biodiversity, an idea in need of further investigation.

Discovery of a significant cave entrance in stripe karst, Horsethief Creek Group, Wells Gray Provincial Park, British Columbia, Canada

In April 2018, a significant cave entrance was recognized during an aerial survey in Wells Gray Provincial Park, British Columbia. A September 2018 assessment of the site confirmed one of the largest known, and previously undocumented, cave entrances in Canada. The feature is a large vertically walled sink swallowing a small river, likely leading to a spring 2.16 km horizontally from, and 460 m below, the sink. The entrance shaft was partially descended, surveyed, and found to have a volume of over 450 000 m3. Formed in a carbonate unit of the upper Proterozoic Horsethief Creek Group, the cave entrance occurs in stripe karst extending well beyond the known cave drainage. The disappearing river drains an area of 6.3 km2 in a valley containing two small glaciers. The river has a low flow (September) rate estimated at 0.3–0.5 m3/s, comparable with some of the largest sinks in Canada. Historic aerial photographs of the area show the entrance was hidden by perennial snowfields until regional climatic warming caused the snow plug to collapse sometime within the past decade.

20th Century Retreat and Recent Drought Accelerated Extinction of Mountain Glaciers and Perennial Snowfields in the Trinity Alps, California

The Trinity Alps is a compact glaciated subrange of the Klamath Mountains in northwest California with elevations < 2,750 m making it a unique location in the western US to study glacier change. We examined glacier change since the last Little Ice Age advance in the late 19th century by mapping historic glacier areas using clearly defined moraines. At least six glaciers existed in the Trinity Alps around the 1880s and estimated glacier cover was at least 55.4 ha (0.554 km2). We tracked changes in two glaciers and two perennial snowfields since that time. Total glacier area decreased by 79% (43.8 ha to 9.1 ha) from the 1880s to 1994. By 2013, glacier area decreased another 7% of the 1880s area to 6.0 ha. Overall, retreat was similar for Salmon Glacier (–89%) and Grizzly Glacier (–84%), but since 1994 Salmon retreat has been much faster, 53% versus 16% for Grizzly. The extended 2012 to 2016 drought resulted in catastrophic retreat of both glaciers such that by 2015 Salmon Glacier disappeared and Grizzly Glacier retreated to 1.67 ha and partially stagnated, a –97% loss of total glacier area since the 1880s. Two snowfields (3.02 ha total area in 1955) were tracked since 1955, the Mirror Lake snowfield disappeared by the summer of 2013 and the Canyon Creek snowfield disappeared by October 2014. The unusually warm summer temperatures since 2005 combined with extremely low winter precipitation from 2013 to 2015 caused rapid retreat and near elimination of the Trinity Alps perennial snow and ice threatening local biodiversity that depends on these features.

Perennial snow patch detection based on remote sensing data on Tröllaskagi Peninsula, northern Iceland

The understanding of permafrost distribution in Iceland is still limited and current knowledge is mainly based on small scale observations and regional modelling using temperature data. In the Alps Perennial Snow Patches have been considered to protect permafrost from solar radiation and are used as an indicator for the occurrence of local permafrost. In this study perennial snow fields are detected and classified based on aerial and satellite images. Effects of climatic and topographic factors on the snow field occurrence are investigated aiming to provide insight into the distribution of local permafrost in northern Iceland. Multi-temporal optical satellite images (Landsat-5/-7/-8 and Sentinel-2, 1984–2017) have revealed a time-variable distribution of perennial snow patches as possible permafrost indicators on the Tröllaskagi Peninsula in northern Iceland. Calculated normalized difference snow index in combination with different threshold values at the end of summer season within six selected study areas show that several snow patches are present in a time period of over 30 years. Perennial snow patches in the study areas exhibit strong fluctuations in extent due to different local characteristics, e.g. elevation, aspect or topography (plateau/open slopes vs. valleys/cirques). In three of the six study areas snow patches have a high probability of occurrence and the pattern of the distribution is very similar in each time period. Comparison with climate data from nearby weather stations indicates that perennial snow patches can be used in combination with mean annual air temperatures as indicators for local permafrost distributions.

Ecological Stoichiometry of the Mountain Cryosphere

Roughly 10% of the Earth’s surface is permanently covered by glaciers and ice sheets and in mountain ecosystems, this proportion of ice cover is often even higher. From an ecological perspective, ice-dominated ecosystems place harsh controls on life including cold temperature, limited nutrient availability, and often prolonged darkness due to snow cover for much of the year. Despite these limitations, glaciers and perennial snowfields still support diverse, primarily microbial communities, though macroinvertebrates and vertebrates are also present. The availability and mass balance of key elements [(carbon (C), nitrogen (N), phosphorous (P)] are known to influence the population dynamics of organisms, and ultimately shape the structure and function of ecosystems worldwide. While considerable attention has been devoted to patterns of existing biodiversity in mountain cryosphere-influenced ecosystems, the ecological stoichiometry of these habitats has been less studied. Understanding this emerging research arena is particularly pressing in light of the rapid recession of glaciers and perennial snowfields worldwide. In this review, we synthesize existing knowledge of ecological stoichiometry, nutrient availability, and food webs in the mountain cryosphere (specifically glaciers and perennial snowfields). We use this synthesis to develop more general understanding of nutrient origins, distributions, and trophic interactions in the mountain cryosphere. We focus our efforts on three major habitats: glacier surfaces (supraglacial), beneath glaciers (subglacial), and adjacent downstream habitats (i.e., glacier-fed streams and lakes). We compare nutrient availability in mountain cryosphere habitats to comparable habitats on continental ice sheets (e.g., Greenland and Antarctica) and show that, in general, nutrient levels are substantially different between the two. Next, we discuss how ongoing climate warming will alter nutrient and trophic dynamics in mountain glacier-influenced ecosystems. We conclude by highlighting the pressing need for future studies to understand spatial and temporal stoichiometric variation in the mountain cryosphere, ideally with direct comparisons to continental ice sheets, before these imperiled habitats vanish completely.

Extent Changes in the Perennial Snowfields of Gates of the Arctic National Park and Preserve, Alaska

Perennial snowfields in Gates of the Arctic National Park and Preserve (GAAR) in the central Brooks Range of Alaska are a critical component of the cryosphere. They serve as habitat for an array of wildlife, including caribou, a species that is crucial as a food and cultural resource for rural subsistence hunters and Native Alaskans. Snowfields also influence hydrology, vegetation, permafrost, and have the potential to preserve valuable archaeological artifacts. By deriving time series maps using cloud computing and supervised classification of Landsat satellite imagery, we calculated areas and evaluated extent changes. We also derived changes in elevations of the perennial snowfields that remained stable for at least four years. For the study period of 1985 to 2017, we found that total areas of perennial snowfields in GAAR are decreasing, with most of the notable changes in the latter half of the study period. Equilibrium areas, or bright areas, of the snowfields are shrinking, while ablation, or dark areas, are growing. We also found that the snowfields occur at higher elevations over time. Climate change may be altering the distribution, elevation, and extent of perennial snowfields in GAAR, which could affect caribou populations and subsistence lifestyles in rural Alaska.

An inventory and assessment of glaciers, rock glaciers, perennial snowfields, and permafrost landforms in the Teton Range, WY, USA

Glaciers, rock glaciers, and permafrost landforms store water within ice reserves in alpine and periglacial zones. In the Greater Yellowstone Ecosystem of northwestern Wyoming, U.S.A., these landforms charge the hydrological system through meltwater, which raises questions about the ecological impacts of these limited water reserves in a regime trending toward warmer and drier conditions. Here, I investigate the impact of glacier and rock glacier meltwater on the ecological systems within the Grand Teton, Wind River, and Gros Ventre mountain watersheds. This investigation relies on remotely sensed satellite imagery, aerial photography, and Lidar, as well as in situ field data. With these data, I provide a high-resolution inventory of glacial, rock glacial, and permafrost landforms in the GYE.&#x0D; &#x0D; Featured photo by Grand Teton on Flickr. https://flic.kr/p/2hwtrRb

Little Ice Age glaciers and climate in the Mediterranean mountains: a new analysis

Glaciers were common across the Mediterranean mountains during the Little Ice Age. In parts of Turkey some glaciers were several kilometres longer than they are today, whilst in the Pyrenees glaciers were up to several hundred metres longer. In the wettest Mediterranean mountains, such as the Dinaric Alps, many small glaciers and perennial snow patches would have been present. Even in driest and most southerly mountains, such as the High Atlas, small glaciers and perennial snowfields were present. This paper examines the evidence from these two contrasting regions (the western and southern Balkans and the High Atlas) and the climatic significance of glaciers in these areas during the Little Ice Age. Particular focus is given on the climatological controls on glacier mass balance in different climatic conditions. Glaciers in cold and dry climates exhibit different sensitivity to regional climate change compared with glaciers in cold and wet climates. In addition, the factors controlling ablation of glaciers in different climatic regimes can differ considerably, especially the relative contributions and effects of melting and sublimation. All Mediterranean mountain glaciers were strongly controlled by local topoclimatic factors. Avalanche-fed glaciers have proven to be the most resilient to climate change and dramatically increased accumulation from avalanching snow explains the surviving glaciers in the Dinaric Alps and the semi-perennial snow fields of the High Atlas. In addition, geology as well as landscape morphology inherited from Pleistocene glaciations plays a role in explaining the patterns of Little Ice Age glacier distribution and especially the patterns of retreat and survival of these glaciers. The resilience of some of the last remaining Mediterranean glaciers, in the face of warming climate, presents a contradiction and comparisons between glaciers gone and those that remain provides important insight into the future of similar glaciers globally.

Fusion of Multi-Source Satellite Data and DEMs to Create a New Glacier Inventory for Novaya Zemlya

Monitoring glacier changes in remote Arctic regions are strongly facilitated by satellite data. This is especially true for the Russian Arctic where recently increased optical and SAR satellite imagery (Landsat 8 OLI, Sentinel 1/2), and digital elevation models (TanDEM-X, ArcticDEM) are becoming available. These datasets offer new possibilities to create high-quality glacier inventories. Here, we present a new glacier inventory derived from a fusion of multi-source satellite data for Novaya Zemlya in the Russian Arctic. We mainly used Landsat 8 OLI data to automatically map glaciers with the band ratio method. Missing debris-covered glacier parts and misclassified lakes were manually corrected. Whereas perennial snow fields were a major obstacle in glacier identification, seasonal snow was identified and removed using Landsat 5 TM scenes from the year 1998. Drainage basins were derived semi-automatically using the ArcticDEM (gap-filled by the ASTER GDEM V2) and manually corrected using fringes from ALOS PALSAR. The new glacier inventory gives a glacierized area of 22,379 ± 246.16 km2 with 1474 glacier entities &gt;0.05 km2. The region is dominated by large glaciers, as 909 glaciers &lt;0.5 km2 (62% by number) cover only 156 ± 1.7 km2 or 0.7% of the area, whereas 49 glaciers &gt;100 km2 (3.3% by number) cover 18,724 ± 205.9 km2 or 84%. In total, 41 glaciers are marine terminating covering an area of 16,063.7 ± 118.8 km2. The mean elevation is 596 m for all glaciers in the study region (528 m in the northern part, 641 in the southern part). South-east (north-west) facing glaciers cover &gt;35% (20%) of the area. For the smaller glaciers in the southern part we calculated an area loss of ~5% (52.5 ± 4.5 km2) from 2001 to 2016.

Новый подход к дифференциации малых ледников и многолетних снежников на основе длительности непрерывного существования гляциально-нивального объекта (на примере гор Кузнецкого Алатау)

Новый подход к дифференциации малых ледников и многолетних снежников на основе длительности непрерывного существования гляциально-нивального объекта (на примере гор Кузнецкого Алатау)

The Geography of Glaciers and Perennial Snowfields in the American West

ABSTRACTA comprehensive mid-20th century inventory of glaciers and perennial snowfields (G&PS) was compiled for the American West, west of the 100° meridian. The inventory was derived from U.S. Geological Survey 1:24,000 topographic maps based on aerial photographs acquired during 35 years, 1955–1990, of which the first 20 years or more was a cool period with little glacier change. The mapped features were filtered for those greater than 0.01 km2. Results show that 5036 G&PS (672 km2, 14 km3) populate eight states, of which about 1276 (554 km2, 12 km3) are glaciers. Uncertainty is estimated at ±9% for area and ±20% for volume. Two populations of G&PS were identified based on air temperature and precipitation. The larger is found in a maritime climate of the Pacific Northwest, characterized by warm winter air temperatures and high winter precipitation (~2100 mm). The other population is continental in climate, characterized by cold winter air temperatures, relatively low winter precipitation (~880 mm), and located at higher elevations elsewhere. The G&PS in the Pacific Northwest, especially in the Olympic Mountains, are particularly vulnerable to warming winter air temperatures that will change the phase of winter precipitation from snow to rain, further accelerating glacier shrinkage in the future. Comparison with a recent inventory suggests that the total G&PS area in the American West may have decreased by as much as 39% since the mid-20th century.

Determining annual cryosphere storage contributions to streamflow using historical hydrometric records

AbstractAlpine glaciers and perennial snow fields are important hydrologic elements in many mountain environments providing runoff during the late summer and during periods of drought. Because relatively long records of glacier mass–balance data are absent from many glacierized catchments, it remains unclear to what extent shrinking perennial snow and glaciers have affected runoff trends from these watersheds. Here, we employ a hydrograph separation technique that uses a double mass curve in an attempt to isolate changes in runoff due to glacier retreat and disappearance of perennial snow. The method is tested using hydrometric data from 20 glacierized and 16 nonglacierized catchments in the Columbia Basin of Canada. The resulting estimates on cryosphere storage contribution to streamflow were well correlated to other regional estimates on the basis of measurements as well as empirical and mechanistic models. Annual cryosphere runoff changed from +19 to −55% during the period 1975–2012, with an average decline of 26%. For August runoff, these changes ranged from +17 to −66%, with an average decrease of 24%. Reduction of cryosphere contributions to annual and late summer flows is expected to continue in the coming decades as glaciers and the perennial snow patches shrink. Our method to isolate changes in late summer cryospheric storage contributions can be used as a first order estimate on changes in glacier contributions to flow and may help researchers and water managers target watersheds for further analysis.

Climate change and the size of glaciers in the Kuznetsky Alatau Mountains between 1975 and 2015

Climate change in the Kuznetsky Alatau (Western Siberia) highlands (on its eastern macroslope) was investigated using data of the Nenasthaya weather station collected for the last 40 years. It is the only highland station functioning now in the area under investigation. Basing on the correlation between average daily temperatures for the period 1974–1975, obtained at the Nenasthaya station and meteopost Karatash (located in front of the Kartash Glacier), we believe that the Nenasthaya one is enough representative for analysis of the climate in this glacio-nival zone. Linear trends for mean summer temperatures and annual precipitation sums had been calculated. Analysis of the linear trends has indicated that for the last 40 years the average summer temperature in the Kuznetsky Alatau increased by 1.3 °C with the growth rate of 0.33 °C/10 years. Average annual precipitation has also increased by 320 mm (the growth rate is 80 mm/10 years). These climatic changes did cause corresponding reactions of glaciers in the area. The analysis of current changes in the glacio-nival systems demonstrated that different morphological types of glaciers reacted to the current climate change in different ways. Small slope glaciers and perennial snowfields degraded significantly (70–90% of the area had melted) due to the temperature rise. Some ones transformed into the category of perennial snowfields. Large corrie glaciers located on the leeward slopes of wide watersheds in the negative relief forms did only slight retreat. They mostly continue to exist because the amount of accumulated snow mass increased and, thus, compensated the ablation. The largest decrease in the area of glaciers took place in 2002–2004. Since 2005, large glaciers stopped to degrade and were in relative equilibrium with climate. This article presents estimation of dynamics of the Kuznetsky Alatau glaciers since their cataloging made in the 1980-s, and it contains the detailed information about fluctuation of areas of glaciers Karatash № 56, Cherno-Iyussky № 83, and Tsentralny № 87 in 1975–2015 received from data obtained in field measurements and remote sensing methods. The area increase of some individual glaciers since 2005 is shown. An effort to compare dynamics of main climatic factors having impact on the glaciations with the dynamics of the glacier areas had been made.

Wind tunnel experiments: cold-air pooling and atmospheric decoupling above a melting snow patch

Abstract. The longevity of perennial snowfields is not fully understood, but it is known that strong atmospheric stability and thus boundary-layer decoupling limit the amount of (sensible and latent) heat that can be transmitted from the atmosphere to the snow surface. The strong stability is typically caused by two factors, (i) the temperature difference between the (melting) snow surface and the near-surface atmosphere and (ii) cold-air pooling in topographic depressions. These factors are almost always a prerequisite for perennial snowfields to exist. For the first time, this contribution investigates the relative importance of the two factors in a controlled wind tunnel environment. Vertical profiles of sensible heat and momentum fluxes are measured using two-component hot-wire and one-component cold-wire anemometry directly over the melting snow patch. The comparison between a flat snow surface and one that has a depression shows that atmospheric decoupling is strongly increased in the case of topographic sheltering but only for low to moderate wind speeds. For those conditions, the near-surface suppression of turbulent mixing was observed to be strongest, and the ambient flow was decoupled from the surface, enhancing near-surface atmospheric stability over the single snow patch.