SeaRISE experiment revisited: sources of spread in multi-model projections of the Greenland ice-sheet
Summary: This article, as the title denotes, is a follow-up study of
an ice-sheet intercomparison project SeaRISE, which focuses on the
response of Greenland ice-sheet to future global warming.
The projections of the different SeaRISE participants 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.
Quantifying the resolution level where the GRACE satellites can separate Greenland's glacial mass balance from surface mass balance
Summary: Separating surface mass balance from glacial mass balance over Greenland would provide important climatological information and constraints for models, but due to poor spatial resolution, the GRACE gravity satellites cannot ordinarily accomplish this. We demonstrate a least-squares technique which allows us to do so, in theory. However we also find that the GRACE errors are too large to make it practical for real-world use at this time. About a 9-fold reduction in noise would be needed.
Satellite passive microwave measurements of sea ice concentration: an optimal algorithm and challenges
Summary: An optimal approach is suggested to retrieve sea ice concentration globally for climate monitoring purposes. This is a result of a validation and inter-comparison experiment with thirty satellite passive microwave algorithms (13 shown to demonstrate the findings) where their skills are evaluated over low and high sea ice concentrations, thin ice and areas covered by melt ponds. In addition, atmospheric correction of input brightness temperatures and dynamic tie-points approach are suggested.
N. Ivanova, L. T. Pedersen, R. T. Tonboe, S. Kern, G. Heygster, T. Lavergne, A. Sørensen, R. Saldo, G. Dybkjær, L. Brucker, and M. Shokr The Cryosphere Discuss., 9, 1269-1313, 2015 AbstractDiscussion Paper (PDF, 1406 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for TC
26 Feb 2015
Soot on snow experiments: light-absorbing impurities effect on the natural snowpack
Summary: Soot's (including black carbon and organics) negative effect on a natural snow pack is experimentally addressed in this paper through a series of experiments. Soot concentrations in the snow in the range of 200-200 000 ppb verify the negative effects on the albedo, the physical snow characteristics, as well as increasing the melt rate of the snow pack. Our experimental data generally agrees when compared with the Snow, Ice and Aerosol Radiation model.
J. Svensson, A. Virkkula, O. Meinander, N. Kivekäs, H.-R. Hannula, O. Järvinen, J. I. Peltoniemi, M. Gritsevich, A. Heikkilä, A. Kontu, A.-P. Hyvärinen, K. Neitola, D. Brus, P. Dagsson-Waldhauserova, K. Anttila, T. Hakala, H. Kaartinen, M. Vehkamäki, G. de Leeuw, and H. Lihavainen The Cryosphere Discuss., 9, 1227-1267, 2015 AbstractDiscussion Paper (PDF, 1952 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for TCSpecial Issue
26 Feb 2015
Brief Communication: Future avenues for permafrost science from the perspective of early career researchers
Summary: This is a contribution about the future of permafrost research to the 3rd International Conference on Arctic Research Planning 2015 (ICARP III).
We summarize the top five research questions for the next decade of permafrost science from the perspective of early career researchers (ECR).
We highlight the pathways and structural preconditions to address these research priorities.
This manuscript is an outcome of a community consultation conducted for and by ECR on a global level.
M. Fritz, B. N. Deshpande, F. Bouchard, E. Högtröm, J. Lepage, A. Morgenstern, A. Nieuwendam, M. Oliva, M. Paquette, A. C. A. Rudy, M. B. Siewert, Y. Sjöberg, and S. Weege The Cryosphere Discuss., 9, 1209-1225, 2015 AbstractDiscussion Paper (PDF, 248 KB)Supplement (358 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for TC
25 Feb 2015
Summer snowfall on the Greenland Ice Sheet: a study with the updated regional climate model RACMO2.3
Summary: We compare Greenland ice sheet surface mass balance (SMB) from the updated polar version of the regional climate model RACMO2.3 and the previous version 2.1. RACMO2.3 has an adjusted rainfall-to-snowfall conversion favouring summer snowfall over rainfall. Enhanced summer snowfall reduce melt rates in the ablation zone by covering dark ice with highly reflective fresh snow. This improves the modelled SMB-elevation gradient and surface energy balance compared to observations in west Greenland.
B. Noël, W. J. van de Berg, E. van Meijgaard, P. Kuipers Munneke, R. S. W. van de Wal, and M. R. van den Broeke The Cryosphere Discuss., 9, 1177-1208, 2015 AbstractDiscussion Paper (PDF, 5792 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for TC
24 Feb 2015
The impact of Saharan dust and black carbon on albedo and long-term glacier mass balance
Summary: Light-absorbing impurities in snow and ice increase the absorption of solar radiation and thus enhance melting. We investigated the effect of Saharan dust and black carbon on the mass balance of an Alpine glacier over 1914-2014. Snow impurities increased melt by 15-19% depending on the location on the glacier. From the accumulation area towards the equilibrium line, the effect of impurities increased as more frequent years with negative mass balance led to a re-exposure of dust-enriched layers.
Arctic sea ice area in CMIP3 and CMIP5 climate model ensembles – variability and change
Summary: The shrinking Arctic sea ice cover is probably the clearest manifestation of ongoing climate change. The last generation of climate models from World Climate Research Programme Coupled Model Intercomparison Project (CMIP3 and CMIP5) simulate consistent changes in the Sea Ice Area (SIA) seasonal cycle. On average, the sensitivity of SIA to external forcing is enhanced in the CMIP5 models. The Arctic SIA variability response to anthropogenic forcing is different in CMIP3 and CMIP5.
Microscale variability of snow depth using U.A.S. technology
Summary: We investigate the capabilities of photogrammetry-based surveys with Unmanned Aerial Systems (U.A.S.) to retrieve the snow depth distribution at cm resolution over a small alpine area. Results show that the U.A.S. technique provides an accurate estimation of point snow depth values, and a distributed evaluation of the snow accumulation patterns.
C. De Michele, F. Avanzi, D. Passoni, R. Barzaghi, L. Pinto, P. Dosso, A. Ghezzi, R. Gianatti, and G. Della Vedova The Cryosphere Discuss., 9, 1047-1075, 2015 AbstractDiscussion Paper (PDF, 2595 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for TC
20 Feb 2015
Tomography-based monitoring of isothermal snow metamorphism under advective conditions
Cloud effects on the surface energy and mass balance of Brewster Glacier, New Zealand
Summary: Clouds are shown to force a fundamental change in the surface energy and mass balance of Brewster Glacier, New Zealand. Greater melt during cloudy periods was associated with enhanced emission of longwave radiation by clouds and increased atmospheric vapour pressure, rather than a minimal change in mean air temperature and wind speed. Surface mass balance was more sensitive to changes in air temperature during cloudy periods due to more frequent melt and a strong precipitation – albedo feedback.
Estimation and calibration of the water isotope differential diffusion length in ice core records
Summary: The diffusion of the stable water isotope signal during firnification of snow is a temperature dependent process. Therefore, past local temperatures can be derived from the differential diffusion length. In this paper we develop a new method for determining this quantity and compare it with the existing method. Both methods are applied to a large number of synthetic data sets to assess the precision and accuracy of the reconstruction and to a section of the Antarctic EDML ice core record.
Parameterization of single-scattering properties of snow
Summary: While snow grains are distinctly non-spherical, spheres are often
assumed in radiative transfer calculations. Here, angular scattering
measurements for blowing snow are used to select an optically
equivalent snow grain shape model. Parameterizations are then developed
for the asymmetry parameter, single-scattering co-albedo and phase
function of snow. The parameterizations will help to improve the
treatment of snow in radiative transfer applications, including remote
sensing and climate models.
Brief Communication: Newly developing rift in Larsen C Ice Shelf presents significant risk to stability
Summary: 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.
D. Jansen, A. J. Luckman, A. Cook, S. Bevan, B. Kulessa, B. Hubbard, and P. R. Holland The Cryosphere Discuss., 9, 861-872, 2015 AbstractDiscussion Paper (PDF, 3871 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for TC
11 Feb 2015
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 meters of firn at Summit, Greenland, by following over a four years period isotope-enriched snow that we deposited.
We found that the diffusion process was much less rapid than in the mostly 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.
L. G. van der Wel, H. A. Been, R. S. W. van de Wal, C. J. P. P. Smeets, and H. A. J. Meijer The Cryosphere Discuss., 9, 817-859, 2015 AbstractDiscussion Paper (PDF, 3693 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for TC
11 Feb 2015
User requirements for the snow and land ice services – CryoLand
Summary: The paper provides detailed information on the outcome of a user survey carried out in the EU FP7 project CryoLand. The project focuses on monitoring of seasonal snow, glaciers and lake/river ice. The user survey showed that a European operational snow and land ice service is required and that there exists products that can meet the specific needs. The majority of the users were mainly interested in the snow services, but also the lake/river ice products and the glacier products were desired.
E. Malnes, A. Buanes, T. Nagler, G. Bippus, D. Gustafsson, C. Schiller, S. Metsämäki, J. Pulliainen, K. Luojus, H. E. Larsen, R. Solberg, A. Diamandi, and A. Wiesmann The Cryosphere Discuss., 9, 791-816, 2015 AbstractDiscussion Paper (PDF, 1352 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for TC
06 Feb 2015
A ground temperature map of the North Atlantic permafrost region based on remote sensing and reanalysis data
Summary: We 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 N Atlantic. A comparison with ground temperatures in boreholes suggests a modeling accuracy of 2 to 2.5 °C.
Recent changes in north-west Greenland climate documented by NEEM shallow ice core data and simulations, and implications for past temperature reconstructions
Summary: The deep NEEM ice core provides the oldest Greenland ice core record,motivating improved understanding of the response of ice core records to local climate. Here, we focus on shallow ice cores providing a stack record of accumulation and water stable isotopes spanning the past centuries. For the first time, we document the ongoing warming in a Greenland ice core. By combining our data with other Greenland ice cores and model results, we characterize the spatio-temporal patterns of variability.
V. Masson-Delmotte, H. C. Steen-Larsen, P. Ortega, D. Swingedouw, T. Popp, B. M. Vinther, H. Oerter, A. E. Sveinbjornsdottir, H. Gudlaugsdottir, J. E. Box, S. Falourd, X. Fettweis, H. Gallée, E. Garnier, J. Jouzel, A. Landais, B. Minster, N. Paradis, A. Orsi, C. Risi, M. Werner, and J. W. C. White The Cryosphere Discuss., 9, 655-717, 2015 AbstractDiscussion Paper (PDF, 6129 KB)Supplement (608 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for TC
29 Jan 2015
Modeling of crack propagation in weak snowpack layers using the discrete element method
Summary: We proposed a new approach to characterize the dynamic phase of crack propagation in weak snowpack layers as well as fracture arrest propensity by means of numerical "Propagation Saw Test" simulations based on the discrete element method. Crack propagation speed and distance before fracture arrest were derived from the simulations for different snowpack configurations and mechanical properties. Numerical and experimental results were compared and the mechanical processes at play were discussed.
Can we retrieve a clear paleoclimatic signal from the deeper part of the EPICA Dome C ice core?
Summary: The oldest paleoclimatic information is buried within the lowermost layers of deep ice cores. It is therefore essential to judge how deep these records remain unaltered. We study the bottom 60 meters of the EPICA Dome C ice core from central Antarctica to show that the paleoclimatic signal is only affected at the small scale (decimeters) in terms of some of the global ice properties. However our data suggest that the time scale has been considerably distorted by mechanical stretching.
J.-L. Tison, M. de Angelis, G. Littot, E. Wolff, H. Fischer, M. Hansson, M. Bigler, R. Udisti, A. Wegner, J. Jouzel, B. Stenni, S. Johnsen, V. Masson-Delmotte, A. Landais, V. Lipenkov, L. Loulergue, J.-M. Barnola, J.-R. Petit, B. Delmonte, G. Dreyfus, D. Dahl-Jensen, G. Durand, B. Bereiter, A. Schilt, R. Spahni, K. Pol, R. Lorrain, R. Souchez, and D. Samyn The Cryosphere Discuss., 9, 567-608, 2015 AbstractDiscussion Paper (PDF, 2759 KB)Supplement (107 KB)Interactive Discussion (Open, 3 Comments)Manuscript under review for TC
28 Jan 2015
Changes in the firn structure of the Greenland Ice Sheet caused by recent warming
Summary: This paper presents an assessment of changes in the near-surface structure of the accumulation zone of the Greenland Ice Sheet caused by an increase of melt at higher elevations in the last decade, especially during the unusually warm years of 2010 and 2012. The increase in melt and firn densification complicate the interpretation of changes in the ice volume, and the observed increase in firn ice content may reduce the important meltwater buffering capacity of the Greenland Ice Sheet.
S. de la Peña, I. M. Howat, P. W. Nienow, M. R. van den Broeke, E. Mosley-Thompson, S. F. Price, D. Mair, B. Noël, and A. J. Sole The Cryosphere Discuss., 9, 541-565, 2015 AbstractDiscussion Paper (PDF, 4644 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for TC
27 Jan 2015
Numerical simulation of extreme snow melt 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 site SIGMA-A was low-level clouds accompanied by a significant temperature increase, which induced surface heating via cloud radiative forcing in the polar region.
M. Niwano, T. Aoki, S. Matoba, S. Yamaguchi, T. Tanikawa, K. Kuchiki, and H. Motoyama The Cryosphere Discuss., 9, 495-539, 2015 AbstractDiscussion Paper (PDF, 1981 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for TC
20 Jan 2015
Snowfall in the Himalayas: an uncertain future from a little-known past
Summary: 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.
Decapitation of high-altitude glaciers on the Tibetan Plateau revealed by ice core tritium and mercury records
S. C. Kang, F. Y. Wang, U. Morgenstern, Y. L. Zhang, B. Grigholm, S. Kaspari, M. Schwikowski, J. W. Ren, T. D. Yao, D. H. Qin, and P. A. Mayewski The Cryosphere Discuss., 9, 417-440, 2015 AbstractDiscussion Paper (PDF, 5028 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for TC
16 Jan 2015
Modelling annual mass balances of eight Scandinavian glaciers using statistical models
Summary: We employ statistical models to model annual glacier mass balances of 8 Scandinavian glaciers as function of ablation-season temperature and accumulation-season precipitation
Relative importances of accumulation-season precipitation and ablation-season temperature vary in time
Relative importance is influenced by AMO and NAO
Climate sensitivities are comparable to degree day models but lower than energy balance models
For the future (2050, 2100) all average annual mass balances are negative
Mapping snow-depth from manned-aircraft on landscape scales at centimeter resolution using Structure-from-Motion photogrammetry
Summary: 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.
A 3-D simulation of drifting snow in the turbulent boundary layer
Summary: Drifting snow is a frequent occurrence natural phenomenon at high latitudes, which has a non-ignorable contribution to the mass balance of ice sheets as well as hydrological balance. The snow drifting process in the turbulent boundary layer is performed and the snow streamers are reproduced. In addition, the particles' velocities along spanwise direction is one order of magnitude smaller than streamwise direction and the diameter distribution along height shows a stratification structure.
Atmospheric and oceanic forcing of Larsen C Ice Shelf thinning
Summary: Many ice shelves on the Antarctic Peninsula 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 data from 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. It is possible that this ice shelf will collapse within decades if its ice front is destabilised.
P. R. Holland, A. Brisbourne, H. F. J. Corr, D. McGrath, K. Purdon, J. Paden, H. A. Fricker, F. S. Paolo, and A. H. Fleming The Cryosphere Discuss., 9, 251-299, 2015 AbstractDiscussion Paper (PDF, 6747 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for TC
13 Jan 2015
A sensitivity study of fast outlet glaciers to short timescale cyclical perturbations
Analysis of long-term precipitation pattern over Antarctica derived from satellite-borne radar
Summary: The aim of this work is to show that the CloudSat Cloud Profiling Radar (CPR) can be a valuable source of snowfall rate data in Antarctica that can be used at different temporal scales. Two years of CloudSat data over Antarctica are analyzed and two different approaches for precipitation estimates are considered. The results show that CPR can provide valuable support to the sparse network of ground-based instruments both for numerical model validation and climatological studies.
L. Milani, F. Porcù, D. Casella, S. Dietrich, G. Panegrossi, M. Petracca, and P. Sanò The Cryosphere Discuss., 9, 141-182, 2015 AbstractDiscussion Paper (PDF, 2886 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for TC
08 Jan 2015
Future projections of the climate and surface mass balance of Svalbard with the regional climate model MAR
Dissolved organic carbon (DOC) in Arctic ground ice
Summary: will be provided later
M. Fritz, T. Opel, G. Tanski, U. Herzschuh, H. Meyer, A. Eulenburg, and H. Lantuit The Cryosphere Discuss., 9, 77-114, 2015 AbstractDiscussion Paper (PDF, 3625 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for TC
07 Jan 2015
Winter observations of CO2 exchange between sea-ice and the atmosphere in a coastal fjord environment
Theoretical framework for estimating snow distribution through point measurements
Summary: In this article, we present a methodology for the objective evaluation of the error in capturing mean snow depths from point measurements. We show using LIDAR snow depths how the model can be used for assisting the design of survey strategies such that the error is minimized or an estimation threshold is achieved. Furthermore, the model can be extended to other spatially distributed snow variables (e.g., SWE) whose statistical properties are comparable to those of snow depth.