Correlations between a 1000 year record of the major ions in a 108.83 m ice core from East Rongbuk Glacier (28°01’N, 86°58’E; 6518ma.s.l.) on the northeast slope of Qomolangma (Mount Everest) and the Southern Oscillation Index (SOI) were examined to investigate possible links between the ice-core records of the southern Tibetan Plateau (TP) and El Niño Southern Oscillation (ENSO). The results show that years with the highest crustal ion concentrations and lowest marine ion concentrations corresponded with a low SOI, and vice versa. Cross wavelet and wavelet coherence analysis between major ion time series and the SOI indicated that there were significant sections with high common power between the major ion time series and the SOI, suggesting a correlation between the ion records of the Qomolangma ice core and ENSO. Further investigation indicated that the higher SOI years corresponded with weaker continental air masses and stronger south Asian monsoons over the southern TP, leading to increased marine ions and decreased continental ions transported to the southern TP. The in-phase surface pressure anomalies of the southern TP and Darwin, Australia, link ENSO and ion transport over the southern TP, and thus suggest a link between aerosol transport over the southern TP and ENSO.

This study presents the first decadal mass-balance record of a small debris-free glacier in the Bhutan Himalaya, where few in situ measurements have been reported to date. Since 2003 we have measured the mass balance of Gangju La glacier, which covers an area of 0.3km2 and extends from 4900 to 5200ma.s.l., using both differential GPS surveys (geodetic method) and stake measurements (direct method). The observed mass balance ranged from –1.12 to –2.04mw.e. a–1 between 2003 and 2014. The glacier exhibited much greater mass loss than neighbouring glaciers in the eastern Himalaya and southeastern Tibet, which are expected to be sensitive to climate change due to the monsooninfluenced humid climate. Observed mass-balance profiles suggest that the equilibrium-line altitude has been higher than Gangju La glacier since 2003, implying that the entire glacier has experienced net ablation for at least the past decade.

Estimates of melt from debris-covered glaciers require distributed estimates of meteorological variables and air temperature in particular. Meteorological data are scarce for this environment, and spatial variability of temperature over debris is poorly understood. Based on multiple measurements of air and surface temperature from three ablation seasons (2012–14) we investigate the variability of temperature over Lirung Glacier, Nepal, in order to reveal how air temperature is affected by the debris cover and improve ways to extrapolate it. We investigate how much on-glacier temperature deviates from that predicted from a valley lapse rate (LR), analyse on-glacier LRs and test regression models of air temperature and surface temperature. Air temperature over the debris-covered glacier tongue is much higher than what a valley LR would prescribe, so an extrapolation from off-glacier stations is not applicable. An on-glacier LR is clearly defined at night, with strong correlation, but not during the day, when the warming debris disrupts the elevation control. An alternative to derive daytime air temperature is to use a relationship between air and surface temperature, as previously suggested. We find strong variability during daytime that should be accounted for if these regressions are used for temperature extrapolation.

Glacier responses to future climate change will affect hydrology at sub-basin scales. The main goal of this study is to assess glaciological and hydrological sensitivities of sub-basins throughout the Hindu Kush-Himalaya region. We use a simple geometrical analysis based on a full glacier inventory and digital elevation model to estimate sub-basin equilibrium-line altitudes (ELAs) from assumptions of steady-state accumulation area ratios. The ELA response to an increase in temperature is expressed as a function of mean annual precipitation, derived from a range of high-altitude studies. Changes in glacier contributions to streamflow in response to increased temperatures are examined for scenarios of both static and adjusted glacier geometries. On average, glacier contributions to streamflow increase by ~50% for a +1 K warming based on a static geometry. Large decreases (-60% on average) occur in all basins when glacier geometries are instantaneously adjusted to reflect the new ELA. Finally, we provide estimates of sub-basin glacier response times that suggest a majority of basins will experience declining glacier contributions by 2100.

Radio-echo sounding techniques are very useful for fast profiling of seasonal snowpack. Ground-penetrating radar (GPR) is used widely for various cryospheric applications, such as snow/glacier depth estimation, snow layer identification and snow water equivalent assessment. The dielectric constant of snow is an important input parameter for the acquisition and interpretation of GPR data from the snowpack. In this study, snow dielectric constant was measured along with physical properties of snow using a snow fork operating at 1 GHz frequency. Experiments were conducted at field observatories of the Snow and Avalanche Study Establishment located in different Himalayan ranges: Patseo (Greater Himalayan range), Dhundhi and Solang (Pir Panjal range). Interseasonal spatial and temporal variations in snow dielectric constant and associated snowpack properties were analysed for five winter seasons (2010-14). The mean seasonal snow dielectric constant is higher at Dhundhi (1.82 ±0.02) than at Patseo (1.69 ±0.02). The measured snow dielectric constant was used to derive snow density and liquid-water content (LWC). A better correlation between snow dielectric constant and LWC is observed for high-density snow (>300kgm-3; R2 = 0.95) than for low-density snow (<200kgm-3; R2 = 0.73). Snow-fork-derived snow density was in good agreement with manually measured values. The snow dielectric constant database generated during this study can be used as a reference for various field applications of GPR in snow-related studies.

We present the updated glaciological mass balance (MB) of Chhota Shigri Glacier, the longest continuous annual MB record in the Hindu-Kush Karakoram Himalaya (HKH) region. Additionally, 4 years of seasonal MBs are presented and analyzed using the data acquired at an automatic weather station (AWS-M) installed in 2009 on a lateral moraine (4863ma.s.l.). The glaciological MB series since 2002 is first recalculated using an updated glacier hypsometry and then validated against geodetic MB derived from satellite stereo-imagery between 2005 (SPOT5) and 2014 (Pléiades). Chhota Shigri Glacier lost mass between 2002 and 2014 with a cumulative glaciological MB of –6.72mw.e. corresponding to a mean annual glacier-wide MB (Ba) of –0.56mw.e. a–1. Equilibrium-line altitude (ELA0) for the steady-state condition is calculated as ~4950ma.s.l., corresponding to an accumulation–area ratio (AAR0) of ~61%. Analysis of seasonal MBs between 2009 and 2013 with air temperature from AWS-M and precipitation from the nearest meteorological station at Bhuntar (1050ma.s.l.) suggests that the summer monsoon is the key season driving the interannual variability of Ba for this glacier. The intensity of summer snowfall events controls the Ba evolution via controlling summer glacier-wide MB (Bs).

Water stored as ice and snow at high elevations is a resource that plays an important role in the hydrologic cycle, particularly in the timing and volume of downstream discharge. Here we use geochemical and isotopic values of water samples to evaluate relative contributions of melting glacier ice and groundwater to discharge in Bhutan. River water samples were collected between 3100 and 4500 m in the Chamkar Chhu (river) watershed of central Bhutan's Himalaya. Glacier ice and snow were sampled in the ablation zone of Thanagang glacier. Groundwater was parameterized from spring water at elevations of 3100 and 3600 m. Synoptic sampling was carried out in separate expeditions in July, August and late September 2014, to characterize monsoon and post-monsoon conditions. Results from a two-component hydrologic mixing model using isotopic and geochemical (sulphate) values show that the glacier outflow contributions decrease from ∼76% at 4500 m to 31% at 3100 m. A four-component hydrologic mixing model using end-member mixing analysis shows glacier ice melt increasing as a proportion of discharge over the 3 month sampling period, and consistently decreasing with distance downstream of Thanagang glacier terminus. These results indicate that isotopic and geochemical tracers can provide a quantitative evaluation of the source water contributions to streamflow in Bhutan.

To simulate a glacial lake outburst flood, we employ a comprehensive physically based general two-phase mass flow model (Pudasaini, 2012). This model accounts for a strong interaction between the solid and fluid phases and incorporates buoyancy and other dominant physical aspects of the mass flows such as enhanced non-Newtonian viscous stress, virtual mass force and generalized drag. Our real two-phase mass flow simulation describes explicit evolution of the solid and fluid phases and the debris bulk as a whole, akin to torrential debris flows or debris floods during glacial lake outburst floods (GLOFs). The emptying of a lake following rapid collapse of a restraining dam, the consequent downslope motion of a mixed solid–fluid mass, and the tendency of the mass to form extruding plumes are analyzed in detail for different flow configurations, volumes, conduit geometries and boundary conditions. The solid and fluid phases evolve completely differently and reveal fundamentally different dynamical behaviours. During the flow, the relatively long fluid tail follows the solid-rich dense frontal surge head. The bulk debris develops into a frontal and side levee as derived from the initial frontal moraine dam. Results show that our high-resolution, unified simulation strategies and the advanced model equations can be applied to study the flow dynamics of a wide range of geophysical mass flows such as snow and rock–ice avalanches, debris flows and flash floods as well as GLOFs. This may help substantially in forming a basis for appropriate mitigation measures against potential natural hazards in high mountain slopes and valleys.

We use numerical modelling of glacier mass balance combined with recent and past glacier extents to obtain information on Little Ice Age (LIA) climate in southeastern Tibet. We choose two glaciers that have been analysed in a previous study of equilibrium-line altitudes (ELA) and LIA glacier advances with remote-sensing approaches. We apply a physically based surface energy- and mass-balance model that is forced by dynamically downscaled global analysis data. The model is applied to two glacier stages mapped from satellite imagery, modern (1999) and LIA. Precipitation scaling factors (PSF) and air temperature offsets (ATO) are applied to reproduce recent ELA and glacier mass balance (MB) during the LIA. A sensitivity analysis is performed by applying seasonally varying gradients of precipitation and air temperature. The calculated glacier-wide MB estimate for the period 2000–12 is negative for both glaciers (–992±366 kgm–2 a–1 and –1053±258 kgm–2 a–1). Relating recent and LIA PSF/ATO sets suggests a LIA climate with ~8–25% increased precipitation and ~1–2.5°C lower mean air temperature than in the period 2000–12. The results only provide an order of magnitude because deviations in other input parameters are not considered.

Photogrammetric measurements of powder-cloud surfaces from large avalanches enable the observation of cloud evolution and dispersion as well as quantification of cloud velocities and powder volumes. Since 2002, a total of six large powder avalanches have been recorded at the test site, Vallée de la Sionne, Switzerland. The high-spatial-resolution photographs, acquired from two different observation angles, allow us to measure the velocity and height of plume-and-cleft structures on the powder-cloud surface. The photogrammetric measurements are supplemented by airborne laser scans of release, entrainment and deposition zones before and after the artificial avalanche release. Even though the precision of the photogrammetric measurements is limited, they are the best data available to test models of powder snow avalanche dynamics. The laser scan data capture initial and boundary conditions while time series of photogrammetric measurements provide insight into mechanisms driving blow-out formation and inertial propagation of the cloud. In this paper we present the experimental measurements and make direct comparisons with model simulations.

We describe changes in glaciers of the Balkhash-Alakol basin, central Asia, and analyse unified glacier inventories of the Zailiyskiy-Kungei and Jungar glacier systems and the Chinese part of the Ili river basin, as well as mass-balance monitoring data from Tsentralniy Tuyuksu glacier for the period 1957-2014. In spite of significant inter-basin differences, glaciation of the three glacial systems in the Ili river basin within Kazakhstan as well as within Chinese territory is changing simultaneously and similarly. Differences in the rates of glacier degradation are small and are affected primarily by the orientation of the flanks of the mountain ridges. Since the mid-1950s, glaciation of the region has remained degraded and, on average over the period examined, glaciers shrank at a rate of about 0.8% a-1 in area and about 1 % a-1 in ice volume. Glacial systems in large basins such as Balkhash-Alakol change simultaneously, linearly and at similar rates. The average rates of glacier reduction of the Zailiyskiy-Kungei, Jungar and upper Ili glacier systems for the period 1955/56-2008 amounted to 0.76%, 0.75% and 0.73% a-1 respectively.