We present simulation results from a version of the Regional Ocean Modeling System modified for ice shelf/ocean interaction, including the parameterisation of basal melting by molecular diffusion alone. Simulations investigate the differences in melting for an idealised ice shelf experiencing a range of cold to hot ocean cavity conditions. Both the pattern of melt and the location of maximum melt shift due to changes in the buoyancy-driven circulation, in a different way to previous studies. Tidal forcing increases both the circulation strength and melting, with the strongest impact on the cold cavity case. Our results highlight the importance of including a complete melt parameterisation and tidal forcing. In response to the 2.4°C ocean warming initially applied to a cold cavity ice shelf, we find that melting will increase by about an order of magnitude (24 × with tides and 41 × without tides).

We have compiled and analysed available records and data on the shrinkage of Satopanth (SPG) and Bhagirath Kharak (BKG) Glaciers, Uttarakhand, India, during the period 1936–2013. We estimate the mean retreat rates of the snouts of SPG and BKG for this period at 9.7±0.8m a–1 and 7.0±0.6m a–1 respectively. We have also revised the estimates of the area vacated during the period 1956–2013 to be 0.27 ± 0.05 km2 and 0.17 ± 0.04 km2 for SPG and BKG respectively, corresponding to front-averaged retreat rates of 5.7±0.6m a–1 and 6.0±0.9m a–1. The study revealed an average thinning of glacial ice in the lower ablation zone of SPG of 9 ± 11 m in the past 51 years. We observed that while the fronts of SPG and BKG depicted in the Survey of India topographic map published in 1962 are inconsistent with other available records, the elevation contours are consistent with them.

Virkisjökull is a rapidly retreating outlet glacier draining the western flanks of Öræfajökull in SE Iceland. Since 2011 there have been continuous measurements of flow in the proglacial meltwater channel and regular campaigns to sample stable isotopes δ2H and δ18O from the river, ice, moraine springs and groundwater. The stable isotopes provide reliable end members for glacial ice and shallow groundwater. Analysis of data from 2011 to 2014 indicates that although ice and snowmelt dominate summer riverflow (mean 5.3–7.9 m3 s−1), significant flow is also observed in winter (mean 1.6–2.4 m3 s−1) due primarily to ongoing glacier icemelt. The stable isotope data demonstrate that the influence of groundwater discharge from moraines and the sandur aquifer increases during winter and forms a small (15–20%) consistent source of baseflow to the river. The similarity of hydrological response across seasons reflects a highly efficient glacial drainage system, which makes use of a series of permanent englacial channels within active and buried ice throughout the year. The study has shown that the development of an efficient year round drainage network within the lower part of the glacier has been coincident with the stagnation and subsequent rapid retreat of the glacier.

Using the Moderate Resolution Imaging Spectroradiometer (MODIS) Level 1 radiance Swath Data (MOD02QKM) with a spatial resolution of 250 m, we derive snowlines during July–September 2001–12 for several mountain ranges distributed across the Tibetan Plateau (TP). Radiance bands 1 and 2 are projected to the study area and processed automatically. The discrimination between snow and ice is done using a k-mean cluster analysis and the snowlines are delineated based on a fixed percentile of the snow-cover altitude. The highest transient snowline altitude is then taken as a proxy for the equilibrium-line altitude (ELA). In the absence of measured glaciological, meteorological or hydrological data, our ELA time series enable better understanding of atmosphere-cryosphere couplings on the TP. Interannual ELA variability is linked to local and remote climate indices using a correlation analysis. Southerly flow and higher temperatures are linked with a higher ELA in most regions. Eastern and Trans-Himalayan sites show positive correlations between winter temperatures and ELA. As winter temperatures are substantially below zero, this suggests an enhancement of winter sublimation as opposed to a reduction in accumulation. It appears that large-scale atmospheric forcing has varying and sometimes opposite influences on the annual ELA in different regions on the TP.

Understanding the hydrology of glacierized catchments is an important step in assessing the vulnerability of water resources to a changing climate. While there have been increased efforts recently to understand the dynamics of Asia's cryosphere, glacier melt dynamics and hydrograph separation of river discharge are open questions. A multi-year, multi-seasonal dataset of water chemistry from the Langtang Valley, Nepal, is used to explore water sources and flow paths that contribute to Langtang River discharge. Differences in hydrochemistry of samples from debris-free Khimsung Glacier and debris-covered Lirung Glacier demonstrate the effect of debris cover on glacier outflow. Additional data show seasonal transitions in the composition of Langtang River discharge. End-member mixing analysis (EMMA) using geochemical and isotopic tracers suggests that reacted meltwater contributes the majority of flow during most of the year, with the exception of the summer when unreacted meltwater and precipitation dominate streamflow. We hypothesize our dataset is missing characteristic monsoon water and utilize a Late May river sample as a proxy for precipitation-influenced groundwater in the EMMA. Results offer insight into the plausibility of flow sources and pathways in the basin.

Despite being a key location for paleoglaciological research in north-central Asia, with the largest number of modern and Pleistocene glaciers, and in the transition zone between the humid Russian Altai and dry Gobi Altai, little is known about the precise extent and timing of Holocene and late Pleistocene glaciations in western Mongolia. Here we present detailed information on the distribution of modern and late Holocene glaciers, and new results addressing the geomorphological differentiation and numerical dating (by optically stimulated luminescence, OSL) of Pleistocene glacial sequences in these areas. For the Mongolian Altai, geochronological results suggest large ice advances correlative to marine isotope stages (MIS) 4 and 2. This is in contrast to results from the Khangai mountains, central Mongolia, showing that significant ice advances additionally occurred during MIS3. During the Pleistocene, glacial equilibrium-line altitudes (ELAs) were ~500 to >1000m lower in the more humid portion of the Russian and western Mongolian Altai, compared to 300-600 m in the drier ranges of the eastern Mongolian Altai. Pleistocene ELAs in the Khangai mountains were depressed by 700-1000 m, suggesting more humid conditions at times of major glaciation than in the eastern Mongolian Altai. This paleo-ELA pattern reveals that the precipitation gradient from the drier to the more humid regions was more pronounced during glacial times than at present.

A long-standing problem in avalanche dynamics is to model the flow of a mixed flowing/powder avalanche. Here we use the thermodynamic concept of configurational energy to describe the blow-out of air from the avalanche core. Configurational energy is the mean potential energy associated with the location of snow and ice particles in the avalanche core. As such, configurational energy determines the avalanche flow density. Expansion of the particle ensemble reduces the flow density and leads to the intake of air. Compression of the particle ensemble causes the blow-out of the intaken air, now laden with ice dust. Once formed, the cloud moves independently of the flowing avalanche with the initial momentum acquired in the core. Configurational energy changes in the avalanche core are therefore intimately related to the formation of the powder suspension cloud. In this paper we use the concept of configurational energy to predict the mass of air taken into and blown out of the core. This requires calculating the dispersive pressure arising from random particle movements and configuration changes related to the expansion and collapse of the flowing particle ensemble. The ice avalanche that struck the Everest base camp on 25 April 2015 is simulated using the proposed concept.

A temperature reconstruction in the glacierized Himalaya over the past centuries using glacial length fluctuation records is challenging due to the abundance of debris-covered glaciers and a scarcity of glacial length fluctuation data. Using idealized flowline model simulations, we show that supraglacial debris cover significantly alters the length fluctuations only when the debris cover is very thick. An expanded database of length fluctuation records for 43 glaciers in the Himalaya and Karakoram is compiled and a standard linear inversion procedure is applied to a subset of 34 glaciers in this database. The reconstructed temperature anomaly during 1860-2010 indicates a continued warming of the region with a total temperature change of ~1.6 K. A close resemblance of the regional temperature anomaly to global trends is seen.

Ice cliffs might be partly responsible for the high mass losses of debris-covered glaciers in the Hindu Kush-Karakoram-Himalaya region. The few existing models of cliff backwasting are point-scale models applied at few locations or assume cliffs to be planes with constant slope and aspect, a major simplification given the complex surfaces of most cliffs. We develop the first grid-based model of cliff backwasting for two cliffs on debris-covered Lirung Glacier, Nepal. The model includes an improved representation of shortwave and longwave radiation, and their interplay with the glacier topography. Shortwave radiation varies considerably across the two cliffs, mostly due to direct radiation. Diffuse radiation is the major shortwave component, as the direct component is strongly reduced by the cliffs’ aspect and slope through self-shading. Incoming longwave radiation is higher than the total incoming shortwave flux, due to radiation emitted by the surrounding terrain, which is 25% of the incoming flux. Melt is highly variable in space, suggesting that simple models provide inaccurate estimates of total melt volumes. Although only representing 0.09% of the glacier tongue area, the total melt at the two cliffs over the measurement period is 2313 and 8282 m3, 1.23% of the total melt simulated by a glacio-hydrological model for the glacier’s tongue.

Air temperature is a key control of processes affecting snow and glaciers in high-elevation catchments, including melt, snowfall and sublimation. It is therefore a key input variable to models of land–surface–atmosphere interaction. Despite this importance, its spatial variability is poorly understood and simple assumptions are made to extrapolate it from point observations to the catchment scale. We use a dataset of 2.75 years of air temperature measurements (from May 2012 to November 2014) at a network of up to 27 locations in the Langtang River, Nepal, catchment to investigate air temperature seasonality and consistency between years. We use observations from high elevations and from the easternmost section of the basin to corroborate previous findings of shallow lapse rates. Seasonal variability is strong, with shallowest lapse rates during the monsoon season. Diurnal variability is also strong and should be taken into account since processes such as melt have a pronounced diurnal variability. Use of seasonal lapse rates seems crucial for glacio-hydrological modelling, but seasonal lapse rates seem stable over the 2–3 years investigated. Lateral variability at transects across valley is high and dominated by aspect, with south-facing sites being warmer than north-facing sites and deviations from the fitted lapse rates of up to several degrees. Local factors (e.g. topographic shading) can reduce or enhance this effect. The interplay of radiation, aspect and elevation should be further investigated with high-elevation transects.

We estimate all the individual glacier area and volume changes in High Mountain Asia (HMA) by 2050 based on Randolph Glacier Inventory (RGI) version 4.0, using different methods of assessing sensitivity to summer temperatures driven by a regional climate model and the IPCC A1B radiative forcing scenario. A large range of sea-level rise variation comes from varying equilibrium-line altitude (ELA) sensitivity to summer temperatures. This sensitivity and also the glacier mass-balance gradients with elevation have the largest coefficients of variability (amounting to ~50%) among factors examined. Prescribing ELA sensitivities from energy-balance models produces the highest sea-level rise (9.2 mm, or 0.76% of glacier volume a–1), while the ELA sensitivities estimated from summer temperatures at Chinese meteorological stations and also from 1°x1° gridded temperatures in the Berkeley Earth database produce 3.6 and 3.8 mm, respectively. Different choices of the initial ELA or summer precipitation lead to 15% uncertainties in modelled glacier volume loss. RGI version 4.0 produces 20% lower sea-level rise than version 2.0. More surface mass-balance observations, meteorological data from the glaciated areas, and detailed satellite altimetry data can provide better estimates of sea-level rise in the future.

Gravitational mass flows may generate tsunamis as they hit water bodies such as oceans, reservoirs or mountain lakes. Upon impact, they can generate tremendous particle-laden or debris flows and floods. Rapidly cascading waves down mountain slopes can trigger debris flows or floods, potentially causing huge damage to civil structures and endangering life. Here we apply a general two-phase mass flow model (Pudasaini, 2012), and present three-dimensional (3-D), high-resolution simulations for a real two-phase debris impacting a fluid reservoir. An innovative formulation provides an opportunity, within a single framework, to simulate simultaneously the sliding two-phase debris/landslide, reservoir, debris impact at reservoir, water-wave generation, propagation and mixing, and separation between solid and fluid phases. The results demonstrate formation and propagation of very special solid and fluid structures in the reservoir, propagation of submarine debris, turbidity currents, and complex interactions between the subaerial debris, surface tsunami and submarine debris waves. Our results reveal that the submerge timescaling for a deformable two-phase debris deviates substantially from the same for a non-deformable solid. These results substantially increase our understanding of 3-D complex multiphase systems/flows. This allows for the proper modeling of landslide/debris-induced mountain tsunami, dynamics of turbidity currents and highly concentrated sediment transports in Himalayan and Alpine slopes and channels, with associated applications to engineering, environmental and hazard-mitigation plans.

This study explores the link between area increase of Imja Tsho (Lake) and changes of Imja Glacier (area ~25km2) under the influence of climate change using multitemporal satellite imagery and local climate data. Between 1962 and 2013, Imja Lake expanded from 0.03±0.01 to 1.35±0.05 km2 at a rate of 0.026±0.001 km2 a-1. The mean glacier-wide flow velocity was 37±30ma-1 during 1992–93 and 23±15ma-1 during 2013–14, indicating a decreasing velocity. A mean elevation change of –1.29±0.71ma-1 was observed over the lower part of the glacier in the period 2001–14, with a rate of –1.06±0.63ma-1 in 2001–08 and –1.56±0.80ma-1 in 2008–14. We conclude that the decrease in flow velocity is mainly associated with reduced accumulation due to a decrease in precipitation during the last few decades. Furthermore, glacier ablation has increased due to increasing maximum temperatures during the post-monsoon months. Decreased glacier flow velocities and increased mass losses induce the formation and subsequent expansion of glacial lakes under favourable topographic conditions.

An ice core was extracted from the Zangser Kangri (ZK) ice field in the northern Tibetan Plateau (NTP), a location with limited instrumental and proxy records. In this paper, we present a continuous high–resolution dust concentration time series spanning the period AD 1951-2008 to investigate variations in atmospheric dust loading over the NTP. The results show that atmospheric dust loading exhibited significant decadal variations, with two periods of high dust loading (AD 1959–67 and AD 1979–89) and three periods of relatively low loading (AD 1951-58, AD 1968–78 and AD 1990–2008). The variability of atmospheric dust loading was related to wind speed at 500 hPa over the dust source regions. The winter Arctic Oscillation (AO) index showed a significant negative correlation with the annual dust concentration, implying a possible connection between the winter AO and the atmospheric dust loading over the NTP.

Two ice cores drilled to the bottom were recovered from Miaoergou flat-topped glacier (43°03'19“N, 94°19'21“E; 4512 ma.s.l.), eastern Tien Shan, central Asia, in 2005. A high–resolution record of cadmium was established by applying inductively coupled plasma mass spectrometry to one of the ice cores (57.6 m), covering a 228 year period from AD 1776 to 2004. The results showed long-term variations of atmospheric transport and deposition of cadmium at high altitudes. Trend analysis based on the sequential Mann-Kendall test and the analysis of crustal enrichment factors of the cadmium shows that natural contribution, mainly from rock and mineral dust, dominated the atmospheric cycles of cadmium during the period AD 1776–1957, which was confirmed by the significant correlation between the winter North Atlantic Oscillation (NAO) index and annual cadmium concentration. The concentration of cadmium increased sharply from AD 1957 to 2004, suggesting increasing influence from human activities, such as metals production. The ice–core record indicated increasing atmospheric cadmium pollution in response to rapid economic growth after AD 1957 in the region.

Snow cover and glaciers in the Karakoram region are important freshwater resources for many down-river communities as they provide water for irrigation and hydropower. A better understanding of current glacier changes is hence an important informational baseline. We present glacier elevation changes in the central Karakoram region using TanDEM-X and SRTM/X-SAR DEM differences between 2000 and 2012. We calculated elevation differences for glaciers with advancing and stable termini or surge-type glaciers separately using an inventory from a previous study. Glaciers with stable and advancing termini since the 1970s showed nearly balanced elevation changes of -0.09 ±0.12 m a-1 on average or mass budgets of -0.01 ±0.02Gt a-1 (using a density of 850 kg m-3). Our findings are in accordance with previous studies indicating stable or only slightly negative glacier mass balances during recent years in the Karakoram. The high-resolution elevation changes revealed distinct patterns of mass relocation at glacier surfaces during active surge cycles. The formation of kinematic waves at quiescent surge-type glaciers could be observed and points towards future active surge behaviour. Our study reveals the potential of the TanDEM-X mission to estimate geodetic glacier mass balances, but also points to still existing uncertainties induced by the geodetic method.