Highlight articles

Results of the third Marine Ice Sheet Model Intercomparison Project (MISMIP+)

We present the results of the third Marine Ice Sheet Intercomparison Project (MISMIP+). MISMIP+ is one in a series of exercises that test numerical models of ice sheet flow in simple situations. This particular exercise concentrates on the response of ice sheet models to the thinning of their floating ice shelves, which is of interest because numerical models are currently used to model the response to contemporary and near-future thinning in Antarctic ice shelves.

The MOSAiC ice floe: sediment-laden survivor from the Siberian shelf

In October 2019 the research vessel Polarstern was moored to an ice floe in order to travel with it on the 1-year-long MOSAiC journey through the Arctic. Here we provide historical context of the floe’s evolution and initial state for upcoming studies. We show that the ice encountered on site was exceptionally thin and was formed on the shallow Siberian shelf. The analyses presented provide the initial state for the analysis and interpretation of upcoming biogeochemical and ecological studies.

Landfast sea ice material properties derived from ice bridge simulations using the Maxwell elasto-brittle rheology

We study the formation of ice arches between two islands using a model that resolves crack initiation and propagation. This model uses a damage parameter to parameterize the presence or absence of cracks in the ice. We find that the damage parameter allows for cracks to propagate in the ice but in a different orientation than predicted by theory. The results call for improvement in how stress relaxation associated with this damage is parameterized.

Towards an objective assessment of climate multi-model ensembles – a casestudy: the Senegalo-Mauritanian upwelling region

The most robust representation of climate is usually obtained by averaging a large number of simulations, thereby cancelling individual model errors. Here, we work towards an objective way of selecting the least biased models over a certain region, based on physical parameters. This statistical method based on a neural classifier and multi-correspondence analysis is illustrated here for the Senegalo-Mauritanian region, but it could potentially be developed for any other region or process.

Changes of the Arctic marginal ice zone during the satellite era

It is well known that the Arctic sea ice extent is declining, and it is often assumed that the marginal ice zone (MIZ), the area of partial sea ice cover, is consequently increasing. However, we find no trend in the MIZ extent during the last 40 years from observations that is consistent with a widening of the MIZ as it moves northward. Differences of MIZ extent between different satellite retrievals are too large to provide a robust basis to verify model simulations of MIZ extent.

RainNet v1.0: a convolutional neural network for radar-based precipitation nowcasting

In this study, we present RainNet, a deep convolutional neural network for radar-based precipitation nowcasting, which was trained to predict continuous precipitation intensities at a lead time of 5 min. RainNet significantly outperformed the benchmark models at all lead times up to 60 min. Yet, an undesirable property of RainNet predictions is the level of spatial smoothing. Obviously, RainNet learned an optimal level of smoothing to produce a nowcast at 5 min lead time.

New observations of the distribution, morphology and dissolution dynamics of cryogenic gypsum in the Arctic Ocean

Based on an observed omnipresence of gypsum crystals, we concluded that their release from melting sea ice is a general feature in the Arctic Ocean. Individual gypsum crystals sank at more than 7000 m d ⁻¹ , suggesting that they are an important ballast mineral. Previous observations found gypsum inside phytoplankton aggregates at 2000 m depth, supporting gypsum as an important driver for pelagic-benthic coupling in the ice-covered Arctic Ocean.

The catastrophic thermokarst lake drainage events of 2018 in northwestern Alaska: Fast-forward into the future

Northwestern Alaska has been highly affected by changing climatic patterns with new temperature and precipitation maxima over the recent years. In particular, the Baldwin and northern Seward peninsulas are characterized by an abundance of thermokarst lakes that are highly dynamic and prone to lake drainage, like many other regions at the southern margins of continuous permafrost. We used Sentinel-1 synthetic aperture radar (SAR) and Planet CubeSat optical remote sensing data to analyze recently observed widespread lake drainage.

Quantification of seasonal and diurnal dynamics of subglacial channels using seismic observations on an Alpine glacier

Our study addresses key questions on the subglacial drainage system physics through a novel observational approach that overcomes traditional limitations. We conducted, over 2 years, measurements of the subglacial water-flow-induced seismic noise and of glacier basal sliding speeds. We then inverted for the subglacial channel’s hydraulic pressure gradient and hydraulic radius and investigated the links between the equilibrium state of subglacial channels and glacier basal sliding.

Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter

Marine-based sectors of the Antarctic Ice Sheet are increasingly contributing to sea-level rise. The basal conditions exert an important control on the ice dynamics. For obvious reasons of inaccessibility, they are an important source of uncertainties in numerical ice flow models used for sea-level projections. Here we assess the performance of an ensemble Kalman filter for the assimilation of transient observations of surface elevation and velocities in a marine ice sheet model.

CR Cryospheric Sciences Highlight articles

Highlight articles

Results of the third Marine Ice Sheet Model Intercomparison Project (MISMIP+)

The MOSAiC ice floe: sediment-laden survivor from the Siberian shelf

Landfast sea ice material properties derived from ice bridge simulations using the Maxwell elasto-brittle rheology

Towards an objective assessment of climate multi-model ensembles – a casestudy: the Senegalo-Mauritanian upwelling region

Changes of the Arctic marginal ice zone during the satellite era

RainNet v1.0: a convolutional neural network for radar-based precipitation nowcasting

New observations of the distribution, morphology and dissolution dynamics of cryogenic gypsum in the Arctic Ocean

The catastrophic thermokarst lake drainage events of 2018 in northwestern Alaska: Fast-forward into the future

Quantification of seasonal and diurnal dynamics of subglacial channels using seismic observations on an Alpine glacier

Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter

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