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.
Comparison of aeolian snow transport events and snow mass fluxes between observations and simulations made by the regional climate model MAR in Adélie Land, East Antarctica
A. Trouvilliez, H. Gallée, F. Naaim-Bouvet, C. Genthon, C. Amory, V. Favier, C. Agosta, L. Piard, and H. Bellot The Cryosphere Discuss., 8, 6007-6032, 2014 AbstractDiscussion Paper (PDF, 1504 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for TC
05 Dec 2014
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.
Weak precipitation, warm winters and springs impact glaciers of south slopes of Mt. Everest (central Himalaya) in the last two decades (1994–2013)
Summary: Climate trends in Himalaya are completely absent at high elevation. We explore the south slopes of Mt Everest though time series reconstructed from 7 stations (2660-5600 m) during 1994-2013. The main increase in temp is concentrated outside of the monsoon, minimum temp increased far more than maximum, while we note a substantial prec weakening. We contribute to change the perspective on which climatic driver (temperature vs. precipitation) led mainly the glacier responses in the last 20 yr
F. Salerno, N. Guyennon, S. Thakuri, G. Viviano, E. Romano, E. Vuillermoz, P. Cristofanelli, P. Stocchi, G. Agrillo, Y. Ma, and G. Tartari The Cryosphere Discuss., 8, 5911-5959, 2014 AbstractDiscussion Paper (PDF, 4918 KB)Supplement (1003 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for TC
01 Dec 2014
Spatiotemporal variations in the surface velocities of Antarctic Peninsula glaciers
Brief Communication: Contending estimates of early 21st century glacier mass balance over the Pamir-Karakoram-Himalaya
Summary: Based on satellite laser altimetry over the Pamir-Karakoram-Himalaya we detect strongest elevation losses over East Nyainqentanglha Shan and Jammu Kashmir, but slight elevation gains over West Kunlun Shan rather than over the Karakoram anomaly. The current sea level contribution of Pamir-Karakoram-Himalaya glaciers is about 10% of the total global contribution of glaciers outside the ice sheets. We also improve estimates of glacier imbalance contribution to river discharge in the Himalayas.
Summary: - Infrared radiation thermography (IRT) was used to assess the surface temperature of avalanches with high spatial resolution.
- Thermal energy increase due to friction was mainly depending on the elevation drop of the avalanche.
- Warming due to entrainment was very specific to the individual avalanche and depends on the temperature of the snow along the path and the erosion depth.
- The warmest temperatures were located in the deposits of the dense core.
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 28.3 km³/winter, this polynya system is of particular interest regarding its potential contribution to deep water formation.
Verification of forecasted winter precipitation in complex terrain
Summary: Numerical Weather Prediction (NWP) models are rarely verified for mountainous regions during the winter season, although avalanche forecasters and other decision makers frequently rely on NWP models. We verified two NWP models (GEM-LAM and GEM15) and a precipitation analysis system (CaPA) at approximately 100 stations in the mountains of western Canadian and northwestern US. Ultrasonic snow depth sensors and snow pillows were used to observe daily precipitation amounts.
Factors controlling Slope Environmental Lapse Rate (SELR) of temperature in the monsoon and cold-arid glacio-hydrological regimes of the Himalaya
Summary: Slope environmental lapse rate of temperature in the monsoon and cold-arid regimes of the higher Himalaya is found to be varying between 9.0 to 1.9oC/km and 17.0 to 2.8oC/km respectively highlighting strong regional variability. Moisture availability/absence is found to be the key factor forcing the lapse rate variability. Present study also provided a modelling solution for estimating the lapse rate.Study suggests that the arbitrary use of lapse rate in the Himalaya is is extremely untenable
Snow mass decrease in the Northern Hemisphere (1979/80–2010/11)
Summary: In this manuscript, we verified the snow water equivalent (SWE) products with large amounts of ground stations and generated an optimized SWE product covering (1979/80-2010/11). Using the optimized product it was found that the SWE is significantly decreasing in the past 32 years, and the decreasing is closely related to temperature rising.
Strategy of valid 14C dates choice in syngenetic permafrost
Summary: The strategy of valid 14С dates choice in syngenetic permafrost includes several points such as:
• Re-deposition of organic matter in the permafrost is common. Syngenetic sediments contain allochthonous organic deposit that originated at a distance from its present position. There needs to be a careful cull of the manifestly more ancient 14C dates.
• The youngest 14C date from the data set in the particular horizon is closest to the actual time of accumulation and freezing of the yedoma
Simulating the Antarctic ice sheet in the Late-Pliocene warm period: PLISMIP-ANT, an ice-sheet model intercomparison project
B. de Boer, A. M. Dolan, J. Bernales, E. Gasson, H. Goelzer, N. R. Golledge, J. Sutter, P. Huybrechts, G. Lohmann, I. Rogozhina, A. Abe-Ouchi, F. Saito, and R. S. W. van de Wal The Cryosphere Discuss., 8, 5539-5588, 2014 AbstractDiscussion Paper (PDF, 4338 KB)Supplement (551 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for TC
05 Nov 2014
Model calibration for ice sheets and glaciers dynamics: a general theory of inverse problems in glaciology
Summary: Inverse problems (IPs) are fundamental to calibrate numerical models, but are not yet widely diffused in glaciology, even if some theroretical developments and excellent applications were published.
This paper provides a conceptual framework for IP in cryospheric sciences, which permits to clearly define and discuss the properties of IP.
The examined topics include: the role of data and parameters: the link of ill-posedness with ill-conditioning and identifiability; sensitivity analysis.
Quantifying meltwater refreezing along a transect of sites on the Greenland Icesheet
Summary: On the Greenland Ice Sheet, a significant quantity of surface melt water refreezes after infiltrating into the cold underlying firn. This paper presents a new method for estimating the amount of water refreezing using temperature measurements. The method is applied to temperature data from a transect of 11 sites and the results provide some of the first measurement based estimates of refreezing quantities which can be used to improve modeling and better understand the refreezing process.
Improving semi-automated glacial mapping with a multi-method approach: areal changes in Central Asia
Summary: We describe and employ a newly developed glacial mapping algorithm which uses spectral, topographic, velocity, and spatial data to quickly and accurately map glacial extents over a wide area. We test this algorithm on glaciers in Central Asia, and show a gradient in glacier area loss rates where those closer to the west (Pamir) are shrinking slower than those towards the east (Tien Shan). We explain this pattern with a noticeable precipitation and storm intensity gradient in the region.
Modelling glacier change in the Everest region, Nepal Himalaya
Summary: Using a glacier mass balance and redistribution model tuned to historical data, we develop scenarios of future glacier change in the Everest region of Nepal. Glaciers in the region are concentrated at elevations between 5000 and 6000 m, and we expect them to be highly sensitive to increased temperatures. Using a range of climate models and emission scenarios, our model indicates potential glacier volume decreases of between -73% and -96% by the year 2100.
The melt pond fraction and spectral sea ice albedo retrieval from MERIS data: validation and trends of sea ice albedo and melt pond fraction in the Arctic for years 2002–2011
L. Istomina, G. Heygster, M. Huntemann, P. Schwarz, G. Birnbaum, R. Scharien, C. Polashenski, D. Perovich, E. Zege, A. Malinka, A. Prikhach, and I. Katsev The Cryosphere Discuss., 8, 5227-5292, 2014 AbstractDiscussion Paper (PDF, 11870 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for TC
15 Oct 2014
Site-level model intercomparison of high latitude and high altitude soil thermal dynamics in tundra and barren landscapes
A. Ekici, S. Chadburn, N. Chaudhary, L. H. Hajdu, A. Marmy, S. Peng, J. Boike, E. Burke, A. D. Friend, C. Hauck, G. Krinner, M. Langer, P. A. Miller, and C. Beer The Cryosphere Discuss., 8, 4959-5013, 2014 AbstractDiscussion Paper (PDF, 11047 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for TC
18 Sep 2014
Modelled present and future thaw lake area expansion/contraction trends throughout the continuous permafrost zone