The spatial pattern of glacier surface melt was measured with a resolution of 20–100m within a region extending 1 km up-glacier from the terminus of Rhonegletscher, Switzerland. The melt rate was monitored from 6 July to 6 September 2009 using 44 ablation stakes. We also measured the surface albedo near the stakes to investigate the importance of this parameter for the melt-rate distribution. The melt rate varied from 32.8 to 71.9 mm w.e. d–1 in the study area. Our measurements suggest that the spatial variation of the melt rate can be explained by (1) shading of the ice surface by neighbouring mountains, (2) surface albedo and (3) effects of microclimate (e.g. radiation from sidewalls) on the surface energy balance. The observed melt-rate distribution was compared to the results of a temperature-index melt model, which takes into account shading of direct solar illumination but not the other two effects. The model reproduces some important features of the field data, but its spatial variations are generally less than the measured values. Our study shows the importance of albedo and other local conditions in the accurate estimation of the small-scale melt-rate distribution.

Catastrophic floods originating from glacial lake outbursts have recently become one of the primary natural hazards in the southeastern Tibetan Plateau. Here we report observations of glacial lake expansions and glacier recessions in the Boshula mountain range, southeast Tibet, derived from multitemporal remote-sensing images and digital elevation models during the period from the 1970s to 2009. The area of glacial lakes has expanded from 10.96 ± 0.1 km2 in the 1970s to 10.96±0.1km2 in 2009. Specifically, the area of moraine-dammed lakes has increased by 26.8%. From the 1970s to 2009, the glacierized area in the Boshula mountain range shrank by 12.7% (21.2 km2). Increasing mean summer air temperature was the main cause for the glacier recession and lake expansion from the 1970s to 2001, while the combination of increased summer temperature and decreased summer precipitation led to accelerated glacier recession after 2001. Climate warming and ongoing deglaciation play important roles in the expansion of moraine-dammed lakes, calling for intensified monitoring to properly address the hazard potential in the study area.

Locations of subglacial lakes discovered under fast-moving West Antarctic ice streams tend to be associated with topographic features of the subglacial bed or with areas that have strong variations in basal conditions. Inversion of ice-stream surface velocity indicates that basal conditions under ice streams can be highly variable and that there can be widespread regions where basal traction is high. To seek an explanation for why lakes appear to be sited near areas with high basal traction, we use numerical models to simulate ice-stream dynamics, thermodynamics and subglacial water flow. We demonstrate that the ice flow over high basal traction areas produces favourable conditions for the ponding of meltwater. Energy dissipation associated with ice sliding over a region with high basal traction constitutes a water source supplying a lake, and ice-thickness perturbations induced by ice flow over variable traction create local minima in hydraulic potential. Variations in thermodynamic processes caused by such ice flow could be responsible for limiting the horizontal extent of the subglacial lakes.

SeaRISE (Sea-level Response to Ice Sheet Evolution) is a US-led multi-model community effort to predict the likely range of the contribution of the Greenland and Antarctic ice sheets to sea-level rise over the next few hundred years under global warming conditions. The Japanese ice-sheet modelling community is contributing to SeaRISE with two large-scale, dynamic/thermodynamic models: SICOPOLIS and IcIES. Here we discuss results for the Greenland ice sheet, obtained using both models under the forcings (surface temperature and precipitation scenarios) defined by the SeaRISE effort. A crucial point for meaningful simulations into the future is to obtain initial conditions that are close to the observed state of the present-day ice sheet. This is achieved by proper tuning during model spin-up from the last glacial/interglacial cycle to today. Experiments over 500 years indicate that both models are more sensitive (exhibit a larger rate of ice-sheet mass loss) to future climate warming (based on the A1B emission scenario) than to a doubling in the basal sliding speed. Ice-sheet mass loss varies between the two models by a factor of ~2 for sliding experiments and a factor of ~3 for climate-warming experiments, highlighting the importance of improved constraints on the parameterization of basal sliding and surface mass balance in ice-sheet models.

To investigate the impact of proglacial lake formation on the dynamics and evolution of glaciers, we measured the ice motion of the terminal part of Rhonegletscher, Switzerland, where a lake formed in 2005. In 2009, the flow velocity near the terminus was >20 m a−1. One of the survey stakes tripled its velocity between 2006 and 2007. Since the lake water pressure was consistently close to the ice overburden pressure, it is likely that the high subglacial water pressure enhanced the basal ice motion. The estimated flow velocity due to ice shearing was negligibly small; almost 100% of the horizontal velocity near the terminus was caused by basal sliding. The longitudinal strain rate was large, 0.064 a–1, indicating that much of the glacier thinning was due to ice dynamics. The region of ice flotation adjacent to the lake expanded between 2008 and 2009 as a result of glacier thinning. Accordingly, a huge uplift of the surface was observed in 2009. It is clear from the vertical ice motion as well as visual observations that the marginal part of the glacier began to float. The ice-thinning rate in the studied area from 2008 to 2009 was 3.4 ma–1, larger than previous estimates.

Estimating soil-water flow during ground freezing is important for understanding factors affecting spring farming, soil microbial activity below the frozen soil, and permafrost thawing behavior. In this study, we performed a column freezing experiment using three different unsaturated soils (sand, loam and silt loam) to obtain a detailed dataset of temperature, water-content and pressure-head change under freezing conditions. The liquid water content and pressure head in the three soils decreased with decreasing temperature. Three soil temperature stages were found: unfrozen, stagnating near 0˚C and frozen. The temperature and duration of the stagnation stage differed among the soil types. The changes in liquid water content and pressure head during the freezing process were highly dependent on the soil-water retention curve. Water flowed through the frozen area in silt loam and sand, but no water flux was observed in the frozen loam. The freezing soil columns tended to contain more liquid water than estimated from retention curves measured at room temperature, especially at the early stage of freezing.

The Sea of Okhotsk is the southernmost area in the Northern Hemisphere where seasonal sea ice is produced every year. The formation of sea ice drives thermohaline circulation in the Sea of Okhotsk, and this circulation supports the high productivity in the region. However, recent reports have indicated that sea-ice production in the Sea of Okhotsk is decreasing, raising concern that the decreased sea ice will affect not only circulation but also biological productivity in the sea. To reconstruct climatic changes in the Sea of Okhotsk region, we analyzed an ice core obtained from Ichinskaya Sopka (Mount Ichinsky), Kamchatka. We assumed that the remarkable negative peaks of δD in the ice core were caused by expansion of sea ice in the Sea of Okhotsk. Melt feature percentage (MFP), which indicates summer snowmelt, showed high values in the 1950–60s and the mid-1990s–2000s. The high MFP in the 1950–60s was assumed to be caused by an increase in cyclone activity reaching Kamchatka during a negative period of the Pacific Decadal Oscillation index, and that in the 1990–2000s may reflect the increase in solar irradiation during a positive period of the summer Arctic Oscillation index.

Calving from the floating termini of outlet glaciers and ice shelves is just the beginning of an interesting chain of events that can subsequently have important impacts on human life and property. Immediately after calving, many icebergs capsize (roll over by 90°) due to the instability of their initial geometry. As icebergs melt and respond to the cumulative effects of ocean swell, they can also reorient their mass distribution by further capsize and fragmentation. These processes release gravitational potential energy and can produce impulsive large-amplitude surface-gravity waves known as tsunamis (a term derived from the Japanese language). Iceberg-capsize tsunamis in Greenland fjords can be of sufficient amplitude to threaten human life and cause destruction of property in settlements. Iceberg-capsize tsunamis may also have a role in determining why some ice shelves along the Antarctic Peninsula disintegrate ‘explosively’ in response to general environmental warming. To quantify iceberg tsunami hazards we investigate iceberg-capsize energetics, and develop a rule relating tsunami height to iceberg thickness. This rule suggests that the open-water tsunami height (located far from the iceberg and from shorelines where the height can be amplified) has an upper limit of 0.01H where H is the initial vertical dimension of the iceberg.

Here we apply a two-phase flow model to simulate snow avalanche motion. Flowing snow is modeled as a Bingham fluid. Small-scale laboratory experiments were conducted using a rotating viscometer to validate the constitutive model. Experimental scale model test-runs were also performed, and run-out distances and impact pressures obtained in the model tests were reproduced using the two-phase flow model. Comparisons revealed that the simulated results were strongly dependent on the basal friction angle and calculation mesh size. Although the method reproduced the laboratory model results quite well, constitutive aspects of the basal surface remained unsolved. Future research will need to incorporate a numerical technique to handle the basal boundary, such as a boundary-fitted coordinate technique.

The Advanced Land Observing Satellite (ALOS) is relatively new. Its optical sensors are capable of making high-resolution digital surface models (DSMs). For the first time, the task of constructing a regional-scale inventory of glacial lakes based on ALOS data has been undertaken. This study presents the data-processing methods and the results of validation and analysis on the ALOS-based glacial lake inventory of Bhutan in the Himalaya. The analysis based on GPS measurements taken at Metatshota lake in the Mangde Chu sub-basin, one of the glacial lakes assessed as presenting a potential flood danger, shows a validation estimate of 9.5 m for the location of the ALOS-based polygon, with a root mean square of 11.7 m. A comparison with digitized data from the International Centre for Integrated Mountain Development (ICIMOD) shows that positioning and evaluation of terrain changes can be significantly improved using ALOS data. Preliminary analysis of the glacial lakes in four sub-basins, Mo Chu, Pho Chu, Mangde Chu and Dangme Chu, reveals that the frequency distribution of lake sizes biases towards smaller lakes. Glacial lakes 0.01–0.05km2 in area account for ~55% of the total number and occupy 13% of the total area. Together our results demonstrate the usefulness of high-resolution ALOS data with accurate DSMs for studying glacial lakes. High priority must be given to continuously improving and updating the glacial lake inventory with high-resolution satellite data.

Digital elevation models (DEMs), represent the three-dimensional terrain and are the basic input for numerical snow avalanche dynamics simulations. DEMs can be acquired using topographic maps or remote-sensing technologies, such as photogrammetry or lidar. Depending on the acquisition technique, different spatial resolutions and qualities are achieved. However, there is a lack of studies that investigate the sensitivity of snow avalanche simulation algorithms to the quality and resolution of DEMs. Here, we perform calculations using the numerical avalance dynamics model RAMMS, varying the quality and spatial resolution of the underlying DEMs, while holding the simulation parameters constant. We study both channelized and open-terrain avalanche tracks with variable roughness. To quantify the variance of these simulations, we use well-documented large-scale avalanche events from Davos, Switzerland (winter 2007/08), and from our large-scale avalanche test site, Vallée de la Sionne (winter 2005/06).We find that the DEM resolution and quality is critical for modeled flow paths, run-out distances, deposits, velocities and impact pressures. Although a spatial resolution of ∼25m is sufficient for large-scale avalanche modeling, the DEM datasets must be checked carefully for anomalies and artifacts before using them for dynamics calculations.

We used atmospheric air-temperature data from the Chinese radiosonde network to analyze changes in freezing-level heights (FLHs) during the past 48 years and studied their impacts on the cryosphere. We examined radiosonde time-series data from 92 selected Chinese radiosonde network stations. Generally, FLH exhibited a latitudinal zone, declining from the south. The FLH trend during 1958–2005 showed spatial inhomogeneity, most uniform distributions during autumn, and significant upward trends. Temporal variability of FLH in eastern China was briefly associated with El Niño Southern Oscillation events, but the causes of FLH changes in western China require further investigation. FLH in western and northern China has mostly increased since 1958, and might be considered a possible indicator of cryospheric change during the second half of the 20th century. There were significant correlations between FLH and changes in snow cover, glaciers and permafrost.

This study illustrates the relevance of cryospheric changes for, and their impact on, ski tourism in Austria. The results of several case studies on snow reliability, snow production and mass balance in glacier ski resorts in the Ötz and Stubai valleys are summarized. Climate data from Obergurgl (1936ma.s.l.) in the Ötz valley are analyzed with respect to the amount and duration of natural snow cover and the possibility of snow production. A case study on Mittelbergferner focuses on the impacts of glacial recession on a ski resort and possible adaptation measures. From long-term glacier inventory and short-term mass-balance data, the effect of operating ski resorts on glaciers is investigated. At Obergurgl, the probability of both snow cover and snow production is >80% from December to March and decreases significantly in the months before and after this peak season. The interannual variability of snow cover and production is low during the main season and higher in other months. Year-to-year differences are larger than any long-term trend. Glacier ski resorts must adapt to shrinking glacial area and falling glacier surface. Covering the glacier with textiles reduces ablation by 60% and results in significantly less volume loss than on uncovered parts of the glacier. Neither the mass-balance comparison between groomed and ungroomed areas nor the comparison of long-term volume changes between 10 ski resort glaciers and 100 surrounding glaciers showed evidence for an impact of the operation of ski resorts on the glaciers.

To understand the formation of hard snow in the field and its relationship to the physical parameters of snow surfaces, we carried out snowpack observations at a flat and snow-covered field in Barrow, Alaska. These observations were performed in the middle of winter and included two drifting snow events. After the end of each drifting snow event, the minimum snow surface density increased slightly with time and there was a rapid increase in the minimum snow surface hardness. There was no rain during our observations. Therefore, the strong bonds among the snow surface particles were not due to melting and refreezing; they formed because of hardening during water-vapor transport under a temperature gradient and also by exposure of the inner snow layer through erosion. As a consequence, the snow formed a hard surface following the drifting snow events.

Measurements of the chemical composition of the snow pits at Murododaira (2450m a.s.l.), Mount Tateyama, near the coast of the Japan Sea in central Japan, were performed each spring from 2005 through 2008. The mean concentrations of nssSO42– and NO3– are higher than those in snowpack in the 1990s. The pH and nssCa2+ were usually high in the upper parts of 2–3m of snow deposited in the spring, when Asian dust (Kosa) particles are frequently transported. High concentrations of nssSO42– were detected in both the spring and winter layers. The high-nssCa2+ layers usually contained high concentrations of nssSO42–. The results show that not only Kosa particles but also air pollutants might have been transported long-range from the continent of Asia. The concentrations of peroxides were high in the new snow (precipitation particles) and granular snow (coarse grain, melt forms) layers. The peroxide concentrations in the snow layers were negatively correlated with the nssCa2+ concentrations. High peroxide concentrations may be preserved in granular snow layers having low concentrations of nssCa2+.

Changes in the shear strength of faceted crystals were measured and parameterized under equi-temperature conditions in the laboratory. The air temperature and bottom temperature of the snow layer were controlled to create a large temperature gradient for 8.8 days to make faceted crystals. Subsequently, the temperature gradient was eliminated and the snow was kept under equi-temperature conditions (–5°C and –10°C) for 55 days. During the experiments, the snow density and shear strength were measured six times. The measured shear strength was compared with two empirical relationships based on density. One of these relationships addresses the strength of round grains, whereas the other refers to faceted grains. The measured shear strength approached the calculated value for faceted crystals when the temperature gradient was large, whereas it approached that for rounded grains after the temperature gradient was removed. The dry snow metamorphism factor (DSM factor), which expresses the developmental stage of faceted crystals, was used to model the shear strength increase under equi-temperature conditions. The DSM factor indicates shear strength using an empirical equation based on rounded grains or faceted crystals. It is approximately 0 for rounded grains and 1 for faceted crystals. It decreased from 1.04 to 0.84 and 0.79 at –10°C and –5°C, respectively, in 55 days. These results were incorporated into the numerical snowpack model SNOWPACK, which successfully reproduced the experimentally observed increase in shear strength under equi-temperature conditions.

Accurate measurements of snow avalanche flows in forests are rare. To understand how forests can stop avalanches, we study a mixed flowing avalanche that stopped in a cedar (Cryptomeria japonica) forest in Japan. The large-scale dry slab avalanche occurred in the Makunosawa valley in Myoko on 17 February 2008 and damaged many trees. The site contains a geophone and other devices to detect avalanche activity. A nearby meteorological station provides weather information. Post-event observations were made of the scale of the avalanche and tree damage. These showed that the avalanche released from the east-southeast-facing slope at 1700 ma.s.l. Snow debris reached ~770ma.s.l; the horizontal runout distance was ~3000 m. The area of the runout zone was ~10 ha, and the snow water equivalent of debris was 400–1500 mm. The mass of the avalanche was roughly estimated at 5–10×107 kg (1–2×105m3). We used snowpack simulation models to estimate the height of the fracture zone. The simulations revealed that a faceted snow layer formed at 2 m and the stability index was 0.5 (poor) at the time of the avalanche release, due to heavy snowfall. We estimated the avalanche velocity from the bending stress of the broken cedar trees, in order to verify the effect of forests in reducing avalanche velocity. The avalanche was estimated to flow into the forest at a velocity of >26–31ms–1, with a 17 m high powder snow layer and a dense-flow layer <2m in height. It appears to have slowed down and stopped at ~130m after penetrating the upper edge of the forest.

The Kodar mountains in eastern Siberia accommodate 30 small, cold-based glaciers with a combined surface area previously estimated at ~19 km2. Very little is known about these glaciers, which were first surveyed in the late 1950s. In this paper, we use terrestrial photogrammetry to calculate changes in the surface area, elevation, volume and geodetic mass balance of Azarova glacier between 1979 and 2007 and relate these to meteorological data from nearby Chara weather station (1938–2007). The glacier surface area declined by 20±6.9% and the surface lowered by an average of 20±1.8m (mean thinning 0.71 ma–1), resulting in a strongly negative cumulative and average mass balance of –18±1.6mw.e. and –640±60mm w.e. a–1, respectively. The July–August air temperature increased at a rate of 0.036˚Ca–1 between 1979 and 2007, and the 1980–2007 period was on average ~1˚C warmer than 1938–79. In comparison to the 1961–90 period, regional climate projections for the A2 and B2 CO2 emission scenarios developed using the PRECIS regional climate model indicate that summer temperatures will increase by 2.6–4.7˚C and 4.9–6.2˚C, respectively, during the 2071–2100 period. The annual total of solid precipitation will increase by 20% under the B2 scenario but is projected to decline by 3% under the A2 scenario. Azarova glacier exhibits high sensitivity to climatic warming due to its low elevation and exposure to comparatively high summer temperatures. Further summer warming and a decline in solid precipitation projected under the A2 scenario will force Azarova glacier to retreat further, but the impact of an increase in solid precipitation projected under the B2 scenario is more uncertain and requires further investigation before a more conclusive prediction can be made.

As part of a deep ice-core drilling project, GPS and ice-radar measurements were made in the vicinity of Aurora Peak, Alaska, USA. Surface and bed elevation maps were obtained over an area of 400 m×700 m, which includes the drilling site. Surface flow velocity was measured at 18 locations in the same area. The results showed that the drilling site was situated on a gentle north–south ridge with saddle-shaped surface geometry. The horizontal ice-flow velocity at the drilling site was <0.5ma–1 and the ice generally flowed eastward and westward along the surface slope. The glacier bed slopes to the east and has more complex topography than the ice surface. The drilling site was situated above a bedrock dip, with an ice thickness of 252±10 m. These data constitute important information for estimating the effect of ice flow to the ice core retrieved from the depth of up to 180.17 m.

A one-dimensional evolution equation for the slope-normal velocity profile of a streamwise uniform avalanche over an entrainable bed is derived. The boundary conditions are no slip at the bed, a stress-free surface and constant bed shear stress equal to the shear strength of the snow cover. The resulting equation is solved numerically by means of finite differences on a regular grid with a superposed fine grid near the erosion front that is adjusted at each time-step. The first exploratory simulations yield realistic entrainment rates and show that the entrainment rate tends towards a constant value while the flow depth and the velocity increase linearly with time for all investigated rheologies. It is shown that there indeed exists a rheology-independent asymptotic solution to the equation of motion of an entraining slab if the bottom friction is equal to the bed shear strength; the asymptotic acceleration is found to be half the downslope gravitational acceleration. The model can easily be extended to general path profiles, non-uniform flows and variable snow properties.