Constraints on the δ2H diffusion rate in firn from field measurements at Summit, Greenland
Summary: We performed 2H isotope diffusion measurements in the upper 3 metres of firn at Summit, Greenland, by following over a 4-year period isotope-enriched snow that we deposited. We found that the diffusion process was much less rapid than in the most commonly used model. We discuss several aspects of the diffusion process that are still poorly constrained and might lead to this discrepancy. Quantitative knowledge of diffusion is necessary for use of the diffusion process itself as a climate proxy.
The Cryosphere, 9, 1089-1103, doi:10.5194/tc-9-1089-2015, 2015
Unlocking annual firn layer water equivalents from ground-penetrating radar data on an Alpine glacier
Summary: This study presents a method for estimating annual accumulation rates on a temperate Alpine glacier based on the interpretation of internal reflection horizons in helicopter-borne ground-penetrating radar (GPR) data. In combination with a simple model for firn densification and refreezing of meltwater, GPR can be used not only to complement existing mass balance monitoring programmes but also to retrospectively extend newly initiated time series.
The Cryosphere, 9, 1075-1087, doi:10.5194/tc-9-1075-2015, 2015
Thin-ice dynamics and ice production in the Storfjorden polynya for winter seasons 2002/2003–2013/2014 using MODIS thermal infrared imagery
Summary: The Storfjorden polynya (Svalbard) forms regularly under the influence of strong north-easterly winds. In this study, spatial and temporal characteristics for the period 2002/03-2013/14 were inferred from daily calculated thin-ice thickness distributions, based on MODIS ice surface temperatures and ERA-interim reanalysis. With an estimated average ice production of 28.3km³/winter, this polynya system is of particular interest regarding its potential contribution to deep water formation.
The Cryosphere, 9, 1063-1073, doi:10.5194/tc-9-1063-2015, 2015
Ice-dynamic projections of the Greenland ice sheet in response to atmospheric and oceanic warming
The Cryosphere, 9, 1039-1062, doi:10.5194/tc-9-1039-2015, 2015
The influence of surface characteristics, topography and continentality on mountain permafrost in British Columbia
Summary: In this paper we describe surface and thermal offsets derived from distributed measurements at seven field sites in British Columbia. Key findings are i) a small variation of the surface offsets between surface types; ii) small thermal offsets at all sites; iii) a clear influence of the micro-topography due to snow cover effects; iv) a north--south difference of the surface offset of 4°C in vertical bedrock and of 1.5–-3°C on open gentle slopes; v) only small macroclimatic differences.
The Cryosphere, 9, 1025-1038, doi:10.5194/tc-9-1025-2015, 2015
Oceanic and atmospheric forcing of Larsen C Ice-Shelf thinning
Summary: Antarctic Peninsula ice shelves have collapsed in recent decades. The surface of Larsen C Ice Shelf is lowering, but the cause of this has not been understood. This study uses eight radar surveys to show that the lowering is caused by both ice loss and a loss of air from the ice shelf's snowpack. At least two different processes are causing the lowering. The stability of Larsen C may be at risk from an ungrounding of Bawden Ice Rise or ice-front retreat past a 'compressive arch' in strain rates.
The Cryosphere, 9, 1005-1024, doi:10.5194/tc-9-1005-2015, 2015
Modelling the impact of submarine frontal melting and ice mélange on glacier dynamics
The Cryosphere, 9, 989-1003, doi:10.5194/tc-9-989-2015, 2015
Numerical simulation of extreme snowmelt observed at the SIGMA-A site, northwest Greenland, during summer 2012
Summary: A physical snowpack model SMAP and in situ meteorological and snow data obtained at site SIGMA-A on the northwest Greenland ice sheet are used to assess surface energy balance during the extreme near-surface snowmelt event around 12 July 2012. We determined that the main factor for the melt event observed at the SIGMA-A site was low-level clouds accompanied by a significant temperature increase, which induced surface heating via cloud radiative forcing in the polar region.
The Cryosphere, 9, 971-988, doi:10.5194/tc-9-971-2015, 2015
Evolution of surface velocities and ice discharge of Larsen B outlet glaciers from 1995 to 2013
Summary: We present new analysis of satellite data showing the variability of glacier velocities in the Larsen B area, Antarctic Peninsula, back to 1995. Velocity data and estimates of ice thickness are used to derive ice discharge at different epochs. Velocities of the glaciers remain to date well above the velocities of the pre-collapse period. The response of individual glaciers differs, and velocities show significant temporal fluctuations, implying major variations in ice discharge and mass balance.
The Cryosphere, 9, 957-969, doi:10.5194/tc-9-957-2015, 2015
Future climate and surface mass balance of Svalbard glaciers in an RCP8.5 climate scenario: a study with the regional climate model MAR forced by MIROC5
Summary: We simulated the 21st century Svalbard SMB with the regional model MAR (RCP8.5 scenario). Melt is projected to increase gently up to 2050 and then dramatically increase, with a larger increase in the south of the archipelago. This difference is due to larger ice albedo decrease in the south causing larger increase of absorbed solar radiation. The ablation area is projected to disappear over the entire Svalbard by 2085. The SMB decrease compared to present is projected to contribute 7mm to SLR.
The Cryosphere, 9, 945-956, doi:10.5194/tc-9-945-2015, 2015
Climatic signals from 76 shallow firn cores in Dronning Maud Land, East Antarctica
Summary: The first comprehensive study of a set of 76 firn cores in Dronning Maud Land was carried out. The δ18O of both the plateau and the ice shelf cores exhibit a slight positive trend over the second half of the 20th century. The SMB has a negative trend in the ice shelf cores, but increases on the plateau. Comparison with meteorological data revealed that for the ice shelf regions, atmospheric dynamic effects are more important, while on the plateau, thermodynamic effects predominate.
The Cryosphere, 9, 925-944, doi:10.5194/tc-9-925-2015, 2015
Multi-modal albedo distributions in the ablation area of the southwestern Greenland Ice Sheet
The Cryosphere, 9, 905-923, doi:10.5194/tc-9-905-2015, 2015
Simulating the Antarctic ice sheet in the late-Pliocene warm period: PLISMIP-ANT, an ice-sheet model intercomparison project
Summary: We present results from simulations of the Antarctic ice sheet by means of an intercomparison project with six ice-sheet models. Our results demonstrate the difficulty of all models used here to simulate a significant retreat or re-advance of the East Antarctic ice grounding line. Improved grounding-line physics could be essential for a correct representation of the migration of the grounding line of the Antarctic ice sheet during the Pliocene.
The Cryosphere, 9, 881-903, doi:10.5194/tc-9-881-2015, 2015
Climate regime of Asian glaciers revealed by GAMDAM glacier inventory
Summary: Among meteorological elements, precipitation has a large spatial variability and less observation, particularly in high-mountain Asia, although precipitation in mountains is an important parameter for hydrological circulation. Based on the GAMDAM glacier inventory, we estimated precipitation contributing to glacier mass at the median elevation of glaciers, which is presumed to be at equilibrium-line altitude, by tuning adjustment parameters of precipitation.
The Cryosphere, 9, 865-880, doi:10.5194/tc-9-865-2015, 2015
The GAMDAM glacier inventory: a quality-controlled inventory of Asian glaciers
Summary: We present a new glacier inventory for high-mountain Asia named “Glacier Area Mapping for Discharge from the Asian Mountains” (GAMDAM). Glacier outlines were delineated manually using 356 Landsat ETM+ scenes in 226 path-row sets from the period 1999–2003, in conjunction with a digital elevation model and high-resolution Google EarthTM imagery. Our GAMDAM Glacier Inventory includes 87,084 glaciers covering a total area of 91,263 ± 13,689 km2 throughout high-mountain Asia.
The Cryosphere, 9, 849-864, doi:10.5194/tc-9-849-2015, 2015
A process-based approach to estimate point snow instability
Summary: We present a novel approach to estimate point snow instability based on snow mechanical properties from snow micro-penetrometer measurements. This is the first approach that takes into account the essential processes involved in dry-snow slab avalanche release: failure initiation and crack propagation. Comparison with field observations confirms that the two-step calculation of a stability criterion and a critical crack length is suited to describe point snow instability.
The Cryosphere, 9, 837-847, doi:10.5194/tc-9-837-2015, 2015
How do icebergs affect the Greenland ice sheet under pre-industrial conditions? – a model study with a fully coupled ice-sheet–climate model
The Cryosphere, 9, 821-835, doi:10.5194/tc-9-821-2015, 2015
Simultaneous solution for mass trends on the West Antarctic Ice Sheet
Summary: This paper provides a proof of concept approach for combining multiple observations and inferences to provide rigorous, error-bounded estimates of mass trends and surface processes for the Antarctic ice sheet. Here we apply the method to West Antarctica, using a time-invariant solution by way of proof of concept. Subsequent work will utilise a time evolving approach to the whole ice sheet.
The Cryosphere, 9, 805-819, doi:10.5194/tc-9-805-2015, 2015
Influence of weak layer heterogeneity and slab properties on slab tensile failure propensity and avalanche release area
Summary: Slab tensile failure propensity is examined using a mechanical--statistical model of the slab–-weak layer (WL) system based on the finite element method. This model accounts for WL heterogeneity, stress redistribution by elasticity of the slab and the slab possible tensile failure. For realistic values of the parameters, the tensile failure propensity is mainly driven by slab properties. Hard and thick snow slabs are more prone to wide–scale crack propagation and thus lead to larger avalanches.
The Cryosphere, 9, 795-804, doi:10.5194/tc-9-795-2015, 2015
Sensitivity of airborne geophysical data to sublacustrine and near-surface permafrost thaw
The Cryosphere, 9, 781-794, doi:10.5194/tc-9-781-2015, 2015