Improving Arctic sea ice edge forecasts by assimilating high horizontal resolution sea ice concentration data into the US Navy's ice forecast systems
Summary: This study presents the improvement in the US Navy's operational sea ice forecast systems gained by assimilating high horizontal resolution satellite-derived ice concentration products. A method of blending ice concentration observations from AMSR2 along with a sea ice mask has been developed, resulting in an ice concentration product with high spatial resolution. A significant improvement in the ice edge location has been shown in the operational system assimilating this new product.
The Cryosphere, 9, 1735-1745, doi:10.5194/tc-9-1735-2015, 2015
Exploring the utility of quantitative network design in evaluating Arctic sea ice thickness sampling strategies
Summary: We present a quantitative network design study of the Arctic sea ice-ocean system. For a demonstration, we evaluate two idealised hypothetical flight transects derived from NASA’s Operation IceBridge airborne ice surveys in terms of their potential to improve 10-day to 5-month sea ice forecasts. Our analysis quantifies the benefits of sampling upstream of the target area and of reducing the sampling uncertainty. It further quantifies the complementarity of combining two flight transects.
The Cryosphere, 9, 1721-1733, doi:10.5194/tc-9-1721-2015, 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 (ECRs). 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 ECRs on a global level.
The Cryosphere, 9, 1715-1720, doi:10.5194/tc-9-1715-2015, 2015
Winter observations of CO2 exchange between sea ice and the atmosphere in a coastal fjord environment
The Cryosphere, 9, 1701-1713, doi:10.5194/tc-9-1701-2015, 2015
Black carbon in snow in the upper Himalayan Khumbu Valley, Nepal: observations and modeling of the impact on snow albedo, melting, and radiative forcing
Summary: We detected up to 70 ppb of black carbon (BC) in surface snow in the upper Khumbu Valley, Nepal. With an upgraded snowpack model, including radiative transfer inside the snow, we studied the impact of BC on snow albedo, melting and radiative forcing for the sensitive high altitude regions of the Himalayas. We found that due to BC, the melting of the snow can be shifted by several days up to several weeks depending on meteorological conditions. The impact of BC is larger in dirty snow.
The Cryosphere, 9, 1685-1699, doi:10.5194/tc-9-1685-2015, 2015
ENSO influence on surface energy and mass balance at Shallap Glacier, Cordillera Blanca, Peru
Summary: Using a newly developed open-source tool, we downscale the glacier surface energy and mass balance fluxes at Shallap Glacier. This allows an unprecedented quantification of the ENSO influence on a tropical glacier at climatological time scales (1980-2013). We find a stronger and steadier anti-correlation between Pacific sea-surface temperature (SST) and glacier mass balance than previously reported and provide keys to understand its mechanism.
The Cryosphere, 9, 1663-1683, doi:10.5194/tc-9-1663-2015, 2015
Temporal variations in the flow of a large Antarctic ice stream controlled by tidally induced changes in the subglacial water system
Summary: We use a full-Stokes model to investigate the long period modulation of Rutford Ice Stream flow by the ocean tide. We find that using a nonlinear sliding law cannot fully explain the measurements and an additional mechanism, whereby tidally induced subglacial pressure variations are transmitted upstream from the grounding line, is also required to match the large amplitude and decay length scale of the observations.
The Cryosphere, 9, 1649-1661, doi:10.5194/tc-9-1649-2015, 2015
Retrieving the 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.
The Cryosphere, 9, 1633-1648, doi:10.5194/tc-9-1633-2015, 2015
Impact of debris cover on glacier ablation and atmosphere–glacier feedbacks in the Karakoram
Summary: We investigate the impact of surface debris on glacier energy and mass fluxes and on atmosphere-glacier feedbacks in the Karakoram range, by including debris in an interactively coupled atmosphere-glacier model. The model is run from 1 May to 1 October 2004, with a simple specification of debris thickness. We find an appreciable reduction in ablation that exceeds 5m w.e. on glacier tongues, as well as significant alterations to near-surface air temperatures and boundary layer dynamics.
The Cryosphere, 9, 1617-1632, doi:10.5194/tc-9-1617-2015, 2015
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.
The Cryosphere, 9, 1601-1616, doi:10.5194/tc-9-1601-2015, 2015
Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate
Summary: We used a high-resolution ice sheet model capable of resolving grounding line dynamics (BISICLES) to compute responses of the major West Antarctic ice streams to projections of ocean and atmospheric warming. This is computationally demanding, and although other groups have considered parts of West Antarctica, we think this is the first calculation for the whole region at the sub-kilometer resolution that we show is required.
The Cryosphere, 9, 1579-1600, doi:10.5194/tc-9-1579-2015, 2015
Melt pond fraction and spectral sea ice albedo retrieval from MERIS data – Part 2: Case studies and trends of sea ice albedo and melt ponds in the Arctic for years 2002–2011
The Cryosphere, 9, 1567-1578, doi:10.5194/tc-9-1567-2015, 2015
Melt pond fraction and spectral sea ice albedo retrieval from MERIS data – Part 1: Validation against in situ, aerial, and ship cruise data
The Cryosphere, 9, 1551-1566, doi:10.5194/tc-9-1551-2015, 2015
Area, elevation and mass changes of the two southernmost ice caps of the Canadian Arctic Archipelago between 1952 and 2014
Summary: Located at the far south (~62.5° N) of the Canadian Arctic, Grinnell and Terra Nivea Ice Caps are good climate proxies in this scarce data region. Multiple data sets (in situ, airborne and spaceborne) reveal changes in area, elevation and mass over the past 62 years. Ice wastage sharply accelerated during the last decade for both ice caps, as illustrated by the strongly negative mass balance of Terra Nivea over 2007-2014 (-1.77 ± 0.36 m a-1 w.e.). Possible climatic drivers are also discussed.
The Cryosphere, 9, 1535-1550, doi:10.5194/tc-9-1535-2015, 2015
Meteorological, elevation, and slope effects on surface hoar formation
Summary: We investigate how various meteorological and terrain factors affect surface hoar formation in complex terrain. We modelled the distribution of three surface hoar layers with a coupled NWP - snow cover model, and verified the model with field studies. The layers developed in regions and elevation bands with warm moist air, light winds, and cold snow surfaces. Possible avalanche forecasting applications are discussed.
The Cryosphere, 9, 1523-1533, doi:10.5194/tc-9-1523-2015, 2015
Impact of model developments on present and future simulations of permafrost in a global land-surface model
Summary: 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.
The Cryosphere, 9, 1505-1521, doi:10.5194/tc-9-1505-2015, 2015
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, enabling 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 characterise the spatio-temporal patterns of variability.
The Cryosphere, 9, 1481-1504, doi:10.5194/tc-9-1481-2015, 2015
Response of the large-scale subglacial drainage system of Northeast Greenland to surface elevation changes
The Cryosphere, 9, 1465-1479, doi:10.5194/tc-9-1465-2015, 2015
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.
The Cryosphere, 9, 1445-1463, doi:10.5194/tc-9-1445-2015, 2015
Assimilation of Antarctic velocity observations provides evidence for uncharted pinning points
Summary: We present a comprehensive high-resolution assimilation of Antarctic surface velocities with a flow model. The inferred velocities are in very good agreement with observations, even when compared to recent studies on individual shelves. This quality allows to identify a pattern in the velocity mismatch that points at pinning points not present in the input geometry. We identify seven potential pinning points around Antarctica, for now uncharted, providing prominent resistance to the ice flow.
The Cryosphere, 9, 1427-1443, doi:10.5194/tc-9-1427-2015, 2015