This paper introduce a moving-point approach to model the flow of ice sheets. This particular moving-grid numerical approach is based on the conservation of local masses. This allows the ice sheet margins to be tracked explicitly. A finite-difference moving-point scheme is derived and applied in a simplified context (1-D). The conservation method is also suitable for 2-D scenarios. This paper is a first step towards applications of the conservation method to realistic 2-D cases.

Liquid water stored on the surface of ice sheets and glaciers, such as that in surface (supraglacial) lakes, plays a key role in the glacial hydrological system. Multispectral remote sensing can be used to detect lakes and estimate their depth. Here, we use in situ data to assess lake depth retrieval using the recently launched Landsat 8. We validate Landsat 8-derived depths and provide suggestions for future applications. We apply our method to a case study are in Greenland for summer 2014.

We present an algorithm for continuous ice drift estimation based on coastal and ship radar data. The ice dynamics are estimated based on automatically selected ice targets (virtual buoys, VBs) and an optical flow algorithm. VBs are added when necessary. We show some examples of the tracking and quantities derived from the VB motion.

This article, as the title denotes, is a follow-up study of an ice-sheet intercomparison project SeaRISE, which focuses on the response of the Greenland ice sheet to future global warming. The projections of the different SeaRISE prticipants show diversion, which has not been examined in detail to date. This study detects the main sources of the diversion by a number of sensitivity experiments and shows the importance of initialization methods as well as climate forcing methods.

Digital glacier inventories are invaluable data sets for revealing the characteristics of glacier distribution. However, quantitative comparison of present inventories was not performed. Here, we present a new inventory manually delineated from Advanced Land Observing Satellite (ALOS) imagery and compare it with existing inventories for the Bhutan Himalaya. Quantification of overlapping among available glacier outlines suggests consistency and recent improvement of their delineation quality.

Ice loss from calving and surface melt is estimated at lake-terminating Bridge Glacier, British Columbia, Canada, from 1984 to 2013. Since the glacier's terminus began to float in 1991, calving has accounted for 10-25% of the glacier's total ice loss below the ELA. Overall, calving is a relatively small component of ice loss and is expected to decrease in importance in the future as the glacier retreats onto dry land. Hence, projections of future retreat remain dependent on climatic conditions.

An ensemble batch smoother was used to assess the feasibility of generating a reanalysis estimate of the Greenland ice sheet (GrIS) surface mass fluxes (SMF) via integrating measured ice surface temperatures with a regional climate model estimate. The results showed that assimilation of IST were able to overcome uncertainties in meteorological forcings that drive the GrIS surface processes. We showed that the proposed methodology is able to generate posterior reanalysis estimates of the SMF.

This paper demonstrates the use of the CryoSat-2 SAR altimeter in operational ice charting. We take CryoSat-2 data and compare them to ice charts over the sea-ice-covered regions in the Barents and Kara seas. We also present an automatic classification method for CryoSat-2 measurements that could be used to support navigation. We conclude that SAR altimeter measurements can be valuable to operational ice charting if other data sources are unavailable.

Lewis Glacier has lost > 80 % of its extent since the late 19th century. A sensitivity study using a process-based model assigns this shrinking to decreased atmospheric moisture without increasing air temperatures required. The glacier retreat implies a distinctly different coupling between the glacier's surface-air layer and its surrounding boundary layer, underlining the difficulty of deriving palaeoclimates for larger glacier extents on the basis of modern measurements of small glaciers.

Sea ice conditions in two fjords of Spitsbergen (Isfjorden, Hornsund) have been investigated between 2000-2014 using manual interpretation of 16555 satellite images. The result is two time series dividing the fjord area into "fast ice", "drift ice", and "open water". A significant reduction of fast ice coverage has been found comparing the time periods 2000-2005 and 2006-2014. A new concept, called "days of fast ice coverage" (DFI), is introduced for quantification of fast ice cover.

We demonstrate the opportunities given by high resolution digital elevation models (DEMs) to improve procedures for obtaining mass balance records from archives of aerial photographs. We also describe a geostatistical approach to estimate uncertainty of elevation changes derived by differencing DEMs. This method is more statistically robust than other described in the literature. Our study highlights a common tendency of overestimating this uncertainty, downgrading geodetic mass balance records.

Soil temperature change is a key indicator of the dynamics of permafrost. Using nine process-based ecosystem models with permafrost processes, a large spread of soil temperature trends across the models. Air temperature and longwave downward radiation are the main drivers of soil temperature trends. Based on an emerging observation constraint method, the total boreal near-surface permafrost area decrease comprised between 39 ± 14 × 10³ and 75 ± 14 × 10³ km² yr⁻¹ from 1960 to 2000.

The Antarctic and Greenland ice sheets are drained primarily by fast ice streams that end as ice shelves if they become afloat. Smooth transitions from slow sheet flow to fast stream flow to confined shelf flow are obtained and applied to Byrd Glacier in Antarctica after two upstream subglacial lakes suddenly drained in 2006, and to Jakobshavn Isbrae in Greenland after a confined ice shelf suddenly disintegrated in 2002. Byrd Glacier quickly stabilized, but Jakobshavn Isbrae remains unstable.

We have derived an analytical model for wind-driven free sea ice drift. We allow for partial sea ice cover using the "mixture layer" formulation and explicitly assume an oceanic Ekman layer, separated from the ice by a thin boundary layer. Provided that surface wind field is known, it is easy to calculate sea ice motion using this analytical model. We believe this analytical model is going to be a powerful tool for identifying and quantifying the mechanisms for sea ice variability.

The role of sea ice in the Earth climate system is still under debate, although it is known to influence albedo, ocean circulation, and atmosphere-ocean heat and gas exchange. Here we present a reconstruction of 1950 to 1998 AD sea ice in the Laptev Sea based on the Akademii Nauk ice core (Severnaya Zemlya, Russian Arctic) and halogen measurements. The results suggest a connection between bromine and sea ice, as well as a connection between iodine concentration in snow and summer sea ice.

By analyzing high-resolution lidar products and using statistical methods, we quantified the snow depth dependency on elevation, slope and aspect of the terrain and also the surrounding vegetation in four catchment size sites in the southern Sierra Nevada during snow peak season. The relative importance of topographic and vegetation attributes varies with elevation and canopy, but all these attributes were found significant in affecting snow distribution in mountain basins.

This study presents the first high-resolution (5.5 km) modelled estimate of surface mass balance (SMB) over the period 1979–2014 for the Antarctic Peninsula (AP). Precipitation (snowfall and rain) largely determines the SMB, and is exceptionally high over the western mountain slopes, with annual values > 4 m water equivalent. Snowmelt is widespread over the AP, but only runs off into the ocean at some locations: the Larsen B,C, and Wilkins ice shelves, and along the north-western mountains.

We use a model-ensemble approach for simulating permafrost on the Tibetan Plateau. We identify the uncertainties across models (state-of-the-art land surface models) and across methods (most commonly used methods to define permafrost).

We differentiate between uncertainties stemming from climatic driving data or from physical process parameterization, and show how these uncertainties vary seasonally and inter-annually, and how estimates are subject to the definition of permafrost used.

In this paper it is shown that the sensitivity to the mesh resolution is not improved for a vanishing friction at the grounding line (GL). For a discontinuous friction at the GL, we further show that the results are moreover very sensitive to the way the friction is interpolated in the close vicinity of the GL. In the light of these new insights, new results for the MISMIP3d experiments obtained for higher resolutions than previously published are made available for future comparisons.

Clouds are shown to force fundamental changes in the surface energy and mass balance of Brewster Glacier, New Zealand. Cloudy periods exhibit greater melt due to increased incoming long-wave radiation and higher atmospheric vapour pressure rather than through minimal changes in mean air temperature and wind speed. Surface mass-balance sensitivity to air temperature is enhanced in overcast compared to clear-sky periods due to more frequent melt and a strong precipitation phase to albedo feedback.

We used 60 years of daily meteorological data from 20 stations across the US Northern Great Plains to examine climate trends, focusing on the winter climate. Besides standard climate trends, we computed trends in snowfall amounts, days with precipitation, days with snow, and modelled winter albedo (surface reflectivity). Daily minimum temperatures and days with precipitation increased at most locations, while winter albedo decreased at many stations. There was much spatial variability.

This paper investigates the uncertainty associated with permafrost thaw projections at an intensively monitored site. Permafrost thaw projections are simulated using a thermal hydrology model forced by a worst-case carbon emission scenario. The uncertainties associated with active layer depth, saturation state, thermal regime, and thaw duration are quantified and compared with the effects of climate model uncertainty on permafrost thaw projections.

In this study we present examples of typical small-scale folds observed in the NEEM ice core, North Greenland, and discuss their characteristics. Numerical modelling of viscoplastic deformation and dynamic recrystallisation was used to improve the understanding of the formation of the observed structures under simple shear boundary conditions. We conclude that the folds originate from bands of grains with a tilted lattice relative to the strong lattice preferred orientation below 1500 m depth.

Density is a fundamental property of porous media such as snow. During the MicroSnow Davos 2014 workshop, different approaches (box-, wedge- and cylinder-type density cutters, micro-computed tomography) to measure snow density were applied in a controlled laboratory environment and in the field. In general, results suggest that snow densities measured by different methods agree within 9 %. However, the density profiles resolved by the measurement methods differed considerably.

Small repeating earthquakes occur at the ice-bed interface of the Whillans Ice Stream, West Antarctica. The earthquakes occur as rapidly as 20 earthquakes/s. We conduct numerical simulations of these earthquakes that include elastic and frictional forces as well as seismic wave propagation. We create synthetic seismograms and compare these synthetics to observed seismograms in order to constrain subglacial parameters. We comment on decadal-scale changes in these parameters.

This paper demonstrates how sea ice segmentation using high-resolution multi-polarisation synthetic aperture radar (SAR) can be used to retrieve valuable information about sea ice type during late summer. It adds knowledge to how choice of SAR features influence the information gain and highlights the sea ice segmentation capability of both the C and X band in late summer. The study contributes to an increased understanding of sea ice mapping and monitoring with SAR in the melt season.

Here we pair detailed hydrographic measurements collected with an autonomous underwater vehicle as close as 150 m from the ice–ocean interface of the Saqqarliup sermia–Sarqardleq Fjord system, West Greenland, with modeled and observed subglacial discharge locations and magnitudes. We find evidence of two main types of subsurface glacially modified water localized in space that are consistent with runoff discharged at two locations along the grounding line.

We show that strong electrical self-potential fields are generated in melting in in situ snowpacks at Rhone Glacier and Jungfraujoch Glacier, Switzerland. We conclude that the electrical self-potential method is a promising snow and firn hydrology sensor, owing to its suitability for sensing lateral and vertical liquid water flows directly and minimally invasively, complementing established observational programs and monitoring autonomously at a low cost.

For the first time, this contribution investigates atmospheric decoupling above melting snow in a wind tunnel study. High-resolution vertical profiles of sensible heat fluxes are measured directly over the melting snow patch. The study shows that atmospheric decoupling is strongly increased in topographic sheltering but only for low wind velocities. Then turbulent mixing close to the surface is strongly suppressed, facilitating the formation of cold-air pooling in local depressions.

Regional climate models improve the spatial surface mass balance (SMB) patterns in Antarctica compared to reanalyses, but they deteriorate the representation of interannual variability in SMB. Hence, we implemented additional nudging in our regional climate model RACMO2. Using annual SMB observations of the Twaites drainage basin, Antarctica, we show that this nudging vastly improves the representation of interannual variability without significant deterioration of the modelled mean SMB fields.

To improve the uncertainty in modeling of the permafrost carbon emission associated with the predicted climate warming, it is important to improve the simulation of the current permafrost carbon stock. This work shows how simulation of the frozen carbon in land system models can be improved by better addressing the coupling between plant photosynthesis, soil biogeochemistry, and soil thermodynamics.