Impact of model developments on present and future simulations of permafrost in a global land-surface model The Cryosphere DOI 10.5194/tc-9-1505-2015 7 August 2015 In this paper we use a global land-surface model to study the dynamics of Arctic permafrost. We examine the impact of new and improved processes in the model, namely soil depth and resolution, organic soils, moss and the representation of snow. These improvements make the simulated soil temperatures and thaw depth significantly more realistic. Simulations under future climate scenarios show that permafrost thaws more slowly in the new model version, but still a large amount is lost by 2100. Read more
Mapping snow depth from manned aircraft on landscape scales at centimeter resolution using structure-from-motion photogrammetry The Cryosphere DOI 10.5194/tc-9-1445-2015 5 August 2015 This paper presents a photogrammetric method for measuring topography from manned aircraft with an accuracy of 30 cm and repeatability of 8 cm, at significantly lower cost than other methods. Here we created difference maps to demonstrate that we could measure snow depth with an accuracy of 10 cm compared to over 6000 snow-probe measurements on the ground, but do so over entire watersheds at 10-20 cm spatial resolution rather than just a few transects. Read more
A ground temperature map of the North Atlantic permafrost region based on remote sensing and reanalysis data The Cryosphere DOI 10.5194/tc-9-1303-2015 23 June 2015 The authors of this paper use remotely sensed land surface temperature and land cover in conjunction with air temperature and snowfall from a reanalysis product as input for a simple permafrost model. The scheme is applied to the permafrost regions bordering the North Atlantic. A comparison with ground temperatures in boreholes suggests a modeling accuracy of 2 to 2.5 °C. Read more
Brief Communication: Newly developing rift in Larsen C Ice Shelf presents significant risk to stability The Cryosphere DOI 10.5194/tc-9-1223-2015 15 June 2015 Within the last year, a large rift in the southern part of the Larsen C Ice Shelf, Antarctic Peninsula, propagated towards the inner part of the ice shelf. In this study we present the development of the rift as derived from remote sensing data and assess the impact of possible calving scenarios on the future stability of the Larsen C Ice Shelf, using a numerical model. We find that the calving front is likely to become unstable after the anticipated calving events. Read more
Snowfall in the Himalayas: an uncertain future from a little-known past The Cryosphere DOI 10.5194/tc-9-1147-2015 2 June 2015 Snow and ice provide large amounts of meltwater to the Indus, Ganges and Brahmaputra rivers. In this study we show that climate change will reduce the amount of snow falling in the Himalayas, Hindu Kush and Karakoram substantially. The limited number of observations in remote upper-level terrain makes it difficult to get a complete overview of the situation today, but our results indicate that by 2071–2100 snowfall may be reduced by 30–70% with the strongest anthropogenic forcing scenario. Read more
Modelling glacier change in the Everest region, Nepal Himalaya The Cryosphere DOI 10.5194/tc-9-1105-2015 27 May 2015 A glacier mass balance and redistribution model that integrates field observations and downscaled climate fields is developed to examine glacier sensitivity to future climate in the Everest region of Nepal. The modelled sensitivity of glaciers to future climate change is high, and glacier mass loss is sustained through the 21st century for both middle- and high-emission scenarios. Projected temperature increases will expose large glacier areas to melt and reduce snow accumulations. Read more
Oceanic and atmospheric forcing of Larsen C Ice-Shelf thinning The Cryosphere DOI 10.5194/tc-9-1005-2015 13 May 2015 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. Read more
The GAMDAM glacier inventory: a quality-controlled inventory of Asian glaciers The Cryosphere DOI 10.5194/tc-9-849-2015 6 May 2015 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. GAMDAM glacier inventory: a quality-controlled inventory of Asian glaciers">Read more
On producing sea ice deformation data sets from SAR-derived sea ice motion The Cryosphere DOI 10.5194/tc-9-663-2015 9 April 2015 We present a new method to compute sea ice deformation fields from satellite-derived motion. The method particularly reduces the artificial noise that arises along discontinuities in the sea ice motion field. We estimate that this artificial noise may cause an overestimation of about 60% of sea ice opening and closing. The constant overestimation of the opening and closing could have led in previous studies to a large overestimation of freezing in leads, salt rejection and sea ice ridging. SAR-derived sea ice motion">Read more
Simulating the Greenland ice sheet under present-day and palaeo constraints including a new discharge parameterization The Cryosphere DOI 10.5194/tc-9-179-2015 5 February 2015 Ice discharge into the ocean from outlet glaciers is an important component of mass loss of the Greenland ice sheet. Here, we present a simple parameterization of ice discharge for coarse resolution ice sheet models, suitable for large ensembles or long-term palaeo simulations. This parameterization reproduces in a good approximation the present-day ice discharge compared with estimates, and the simulation of the present-day ice sheet elevation is considerably improved. Read more
