The snow layer on top of the Greenland Ice Sheet is changing: it is thickening in the high and cold interior due to increased snowfall, while it is thinning around the margins. The marginal thinning is caused by compaction, and by more melt. This knowledge is important: there are satellites that measure volume change of the ice sheet. It can be caused by increased ice discharge, or by compaction of the snow layer. Here, we quantify the latter, so that we can translate volume to mass change.

We established a 13-year-long MODIS-derived thin-ice thickness data set from which we derived information about polynya dynamics in the southern Weddell Sea. In contrast to other studies, we do not focus on a single region but instead discuss polynya dynamics for the complete coastal area. The higher spatial resolution of MODIS compared to passive-microwave sensors enables us to resolve even very narrow coastal polynyas that would remain otherwise undetected.

Projections of Antarctic dynamics and contribution to sea-level rise are evaluated in the light of intercomparison exercises dedicated to evaluate models' ability of representing coastal changes. Uncertainties in projections can be substantially decreased if a selection of models is made and models that are unqualified for the representation of coastal dynamics are excluded.

Our work quantifies the effect of snow/ice cover on Earth's top-of-atmosphere solar energy budget. We used higher resolution MODIS data, combined with microwave retrievals of snow presence and radiative kernels produced from 4 different models for Cryosphere Radiative Effect (CrRE) estimation. We have estimated a global land-based CrRE of about -2.6Wm-2 during 2001-2013, with about 59% of the effect originating from Antarctica. We were also be able to resolve contribution from mountain glaciers.

Investigations of glacier mass-balance and area changes at Muztagh Ata (eastern Pamir) are based on Hexagon KH-9 (1973), ALOS-PRISM (2009), Pléiades (2013) and Landsat 7 ETM+/SRTM-3 (2000). Surface velocities of Kekesayi Glacier are derived by TerraSAR-X (2011) amplitude tracking. Glacier variations differ spatially and temporally, but on average not significantly for the entire massif. Stagnant Kekesayi and other debris-covered glaciers indicate no visual length changes, but clear down-wasting.

The extent and distribution of permafrost in the mountainous parts of the Hindu Kush Himalayan (HKH) region are largely unknown. This article provides a first-order assessment of the two available permafrost maps in the HKH region based on the mapping of rock glaciers in Google Earth. The Circum-Arctic Map of Permafrost and Ground Ice Conditions does not reproduce mapped conditions in the HKH region adequately, whereas the Global Permafrost Zonation Index does so with more success.

The paper establishes a theoretical link between two widely used microwave models for snow. The scattering formulations from both models are unified by reformulating their microstructure models in a common framework. The results show that the scattering formulations can be considered equivalent, if exactly the same microstructure model is used. The paper also provides a method to measure a hitherto unknown input parameter for the microwave models from tomography images of snow.

Sea-ice cover is composed of floes of different sizes and thicknesses, whose distribution varies in space and time, and may affect the interaction between sea ice and the ocean and atmosphere, yet is not represented in climate models. We develop and demonstrate a model for the evolution of the joint distribution of floe sizes and thicknesses, subject to melting and freezing, mechanical interactions between floes, and the fracture of floes by waves, forced by atmospheric and ocean forcing fields.

Kurowski suggested in 1891 that ELA is equal to the mean altitude of the glacier when the glacier is in balance. I compare mean altitude with balanced-budget ELA for 103 modern glaciers. Kurowski’s mean altitude is significantly higher (at 95% level) than balanced-budget ELA for 19 outlet and 42 valley glaciers, but not significantly higher for 34 mountain glaciers. The error in Kurowski mean altitude as a predictor of balanced budget might be due to non-linearity in balance gradients.

We modeled snow (based on weather variables) to simulate microwave response. The simulated snowpack, and the simulated microwave backscatter response, was compared to observed physical snow and ice properties and the observed microwave response. There was better agreement between the simulated and observed microwave signatures when we applied observed salinity profiles to the simulated snow pack. Without correction for observed salinity, there was less agreement.

This paper details a new algorithm for performing computational experiments of subglacial granular deformation. The numerical approach allows detailed studies of internal sediment and pore-water dynamics under shear. Feedbacks between sediment grains and pore water can cause rate-dependent strengthening, which additionally contributes to the plastic shear strength of the granular material. Hardening can stabilise patches of the subglacial beds with implications for landform development.

This study uses animations of freely available Landsat images (acquired over 25 years) to reveal glacier flow and surge dynamics in the central Karakoram. The animations provide a holistic view on the timing and variability of glacier dynamics that is hard to obtain by other more quantitative methods. Among others, the study reveals that most surging glaciers are comparably small, steep and debris-free, with a wide range of advance rates and durations, overlapping with non-surge-type glaciers.

During the last centuries hundreds of glaciers in Greenland have been mapped and named. Here we present the official database of all Greenlandic glacier names - consisting of 733 glacier names that have been approved by the Greenlandic authorities. This data set will help researchers working with Greenlandic glaciers in naming the glaciers properly in order to avoid future misunderstandings and will help the researcher who is looking for older glacier names found in the historic literature.

Terrestrial radar interferometry measurements allow us to capture the entire velocity field of several alpine glaciers at Mount Rainier, WA, and investigate glacier dynamics. We analyze spatial patterns and compare repeat measurements to investigate diurnal and seasonal glacier changes. We find no significant diurnal variability but a very large seasonal slowdown (25 to 50%) from July to November likely due to changes in subglacial water storage. Modeling suggests 91-99% of motion is sliding.

Projections of Arctic sea ice thickness (SIT) have the potential to inform stakeholders about accessibility to the region, but are currently rather uncertain. We present a new method to constrain global climate model simulations of SIT to narrow projection uncertainty via a statistical bias-correction technique.

For the first time an ice core unaffected by melting was recovered from the western Elbrus plateau in the Caucasus. The preserved chemical and isotopic data are considered a source of paleo-climate information for southern/eastern Europe. Considerable snow accumulation (about 1500mm w.e.) and high sampling resolution allowed seasonal variability to be obtained in climate signals, covering a time period of about 200 years. Ice flow models suggest that the basal ice age can be more than 600 years.

A verification of the physics based SNOWPACK model with field observations showed that typical snowpack properties like density and temperature are adequately simulated. Also two water transport schemes were verified, showing that although Richards equation improves snowpack runoff and several aspects of the internal snowpack structure, the bucket scheme appeared to have a higher agreement with the snow microstructure. The choice of water transport scheme may depend on the intended application.

A debris-covered glacier energy balance was used to model debris temperatures and sub-debris ablation rates on Imja-Lhotse Shar Glacier during the 2014 melt season. Field measurements were used to assess model performance. A novel method was also developed using Structure from Motion to estimate the surface roughness. Lastly, the effects of temporal resolution, i.e., 6h and daily time steps, and various methods for estimating the latent heat flux were also investigated.

Estimates of the Antarctic surface mass balance with regional climate models (RCMs) require proper fields for forcing; hence we evaluate 41 CMIP5 climate models over Antarctica and include six reanalyses. Most of the models are biased compared to ERA-Interim, ACCESS1-3 being the best choice for forcing RCMs. Climate change is less sensitive to global warming than it is to the present-day simulated sea ice and to the feedback between sea-ice decrease and temperature increase around Antarctica.

Light-absorbing impurities change the reflectance of snow in different ways. Some particles are heated by the Sun and they sink out of sight. During the process, snow may look darker than pure snow when observed by nadir, but at larger view zenith angles the snow may look as white as clean snow. Thus an observer on the ground may overestimate the albedo, while a satellite underestimates the albedo. Climate studies need to examine how the contaminants behave in snow, not only their total amounts.

Kronebreen and Kongsbreen are among the fastest flowing glaciers on Svalbard, and surface speeds reached up to 3.2m d-1 at Kronebreen in summer 2013 and 2.7m d-1 at Kongsbreen in late autumn 2012 as retrieved from SAR satellite data. Both glaciers retreated significantly during the observation period, Kongsbreen up to 1800m or 2.5km2 and Kronebreen up to 850m or 2.8km2. Both glaciers are important contributors to the total dynamic mass loss from the Svalbard archipelago.

We illustrate a method to measure the size distribution of a snow particle metric from macro photos of snow particles. This snow particle metric corresponds well to the optically equivalent effective radius. Our results evidence the impact of grain shape on albedo, indicate that more than just one particle metric distribution is needed to characterize the snow scattering properties at all optical wavelengths, and suggest an impact of surface roughness on the shortwave infrared albedo.

The albedo and surface energy budget of the Antarctic Plateau are largely determined by snow specific surface area. The latter experiences substantial daily-to-seasonal variations in response to meteorological conditions. In particular, it decreases by a factor three in summer, causing a drop in albedo. These variations are monitored from in situ and remote sensing observations at Dome C. For the first time, they are also simulated with a snowpack evolution model adapted to Antarctic conditions.

We show that estimates of global glacier mass change during the 20th century, obtained from glacier-length-based reconstructions and from a glacier model driven by gridded climate observations are now consistent with each other and also with an estimate for the years 2003-2009 that is mostly based on remotely sensed data. This consistency is found throughout the entire common periods of the respective data sets. Inconsistencies of reconstructions and observations persist on regional scales.

Recent trends in ocean circulation, sea ice and climate over the Southern Ocean and Antarctica are highly complex. Here we report a new snow core from the South Pole alongside reanalysis of 20th century global atmospheric circulation. We demonstrate for the first time that atmospheric pressure anomalies in the mid-latitudes act as "gatekeepers" to meridional exchange over continental Antarctica, modulated by the tropical Pacific, with potentially significant impacts on surface mass balance.

The bias corrections show significant errors in the gauge precipitation measurements over the northern regions. Monthly precipitation is closely correlated between the stations across the Alaska--Yukon border, particularly for the warm months. Double mass curves indicate changes in the cumulative precipitation due to bias corrections over the study period. Overall the bias corrections lead to a smaller and inverted precipitation gradient across the border, especially for snowfall.

We calibrate a time-dependent ice model through optimal fit to transient observations of surface elevation and velocity, a novel procedure in glaciology and in particular for an ice stream with a dynamic grounding line. We show this procedure gives a level of confidence in model projections that cannot be achieved through more commonly used glaciological data assimilation methods. We show that Smith Glacier is in a state of retreat regardless of climatic forcing for the next several decades.