Highlight articles

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.

TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI):motivations and protocol version 1.0

Atmospheric characterization of rocky exoplanets orbiting within the habitable zone of nearby M dwarf stars is around the corner with the James Webb Space Telescope (JWST), expected to be launch in 2021.
Global climate models (GCMs) are powerful tools to model exoplanet atmospheres and to predict their habitability. However, intrinsic differences between the models can lead to various predictions. This paper presents an experiment protocol to evaluate these differences.

Cryoconite: an efficient accumulator of radioactive fallout in glacialenvironments

The Cryosphere
DOI 10.5194/tc-14-657-2020
25 February 2020

Cryoconite is the sediment found on the surface of glaciers. The paper presents cryoconite as an environmental matrix able to accumulate natural and artificial radioactivity with unprecedented efficiency. Only samples from sites where nuclear accidents and explosions occurred present a stronger radioactive contamination. The peculiarities of glacial environments are responsible for this extreme feature, making cryoconite a useful tool tool for the monitoring of environmental radioactivity.

An urban ecohydrological model to quantify the effect of vegetation on urban climate and hydrology (UT&C v1.0)

We developed a novel urban ecohydrological model (UT&C v1.0) that is able to account for the effects of different plant types on the urban climate and hydrology, as well as the effects of the urban environment on plant well-being and performance. UT&C performs well when compared against energy flux measurements in three cities in different climates (Singapore, Melbourne, Phoenix) and can be used to assess urban climate mitigation strategies that aim at increasing or changing urban green cover.

A decade of variability on Jakobshavn Isbræ: ocean temperatures pace speedthrough influence on mélange rigidity

Jakobshavn Isbræ, considered to be Greenland’s fastest glacier, has varied its speed and thinned dramatically since the 1990s. Here we examine the glacier’s behaviour over the last decade to better understand this behaviour. We find that when the floating ice (mélange) in front of the glacier freezes in place during the winter, it can control the glacier’s speed and thinning rate. A recently colder ocean has strengthened this mélange, allowing the glacier to recoup some of its previous losses.

Understanding snow bedform formation by adding sintering to a cellular automata model

Snow surfaces, under the action of wind, form beautiful shapes such as waves and dunes. This study is the first ever study to simulate these shapes using a state-of-the-art numerical modelling tool. While these beautiful and ephemeral shapes on snow surfaces are fascinating from a purely aesthetic point of view, they are also critical in regulating the transfer of heat and mass between the atmosphere and snowpacks, thus being of huge importance to the Earth system.

A comparative assessment of the uncertainties of global surface ocean CO2 estimates using a machine-learning ensemble (CSIR-ML6 version 2019a) – have we hit the wall?

The ocean plays a vital role in mitigating climate change by taking up atmospheric carbon dioxide (CO₂). Historically sparse ship-based measurements of surface ocean CO₂make direct estimates of CO₂exchange changes unreliable. We introduce a machine-learning ensemble approach to fill these observational gaps. Our method performs incrementally better relative to past methods, leading to our hypothesis that we are perhaps reaching the limitation of machine-learning algorithms’ capability.

New Last Glacial Maximum ice thickness constraints for the Weddell Sea Embayment, Antarctica

We studied the history of ice masses at three locations in the Weddell Sea Embayment, Antarctica. We measured rare isotopes in material sourced from mountains overlooking the Slessor Glacier, Foundation Ice Stream, and smaller glaciers on the Lassiter Coast. We show that ice masses were between 385 and 800 m thicker during the last glacial cycle than they are at present. The ice masses were both hundreds of metres thicker and remained thicker closer to the present than was previously thought.

Melt at grounding line controls observed and future retreat of Smith, Pope, and Kohler glaciers

We used a number of computer simulations to understand the recent retreat of a rapidly changing group of glaciers in West Antarctica. We found that significant melt underneath the floating extensions of the glaciers, driven by relatively warm ocean water at depth, was likely needed to cause the large retreat that has been observed. If melt continues around current rates, retreat is likely to continue through the coming century and extend beyond the present-day drainage area of these glaciers.

Calving cycle of the Brunt Ice Shelf, Antarctica, driven by changes in ice shelf geometry

Two large icebergs are about to break off from the Brunt Ice Shelf in Antarctica. Rifting started several years ago and is now approaching its final phase. Satellite data and computer simulations show that over the past 2 decades, growth of the ice shelf has caused a build-up of forces within the ice, which culminated in its fracture. These natural changes in geometry coincided with large variations in flow speed, a process that is thought to be relevant for all Antarctic ice shelf margins.

CR Cryospheric Sciences Highlight articles

Highlight articles

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

TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI):motivations and protocol version 1.0

Cryoconite: an efficient accumulator of radioactive fallout in glacialenvironments

An urban ecohydrological model to quantify the effect of vegetation on urban climate and hydrology (UT&C v1.0)

A decade of variability on Jakobshavn Isbræ: ocean temperatures pace speedthrough influence on mélange rigidity

Understanding snow bedform formation by adding sintering to a cellular automata model

A comparative assessment of the uncertainties of global surface ocean CO2 estimates using a machine-learning ensemble (CSIR-ML6 version 2019a) – have we hit the wall?

New Last Glacial Maximum ice thickness constraints for the Weddell Sea Embayment, Antarctica

Melt at grounding line controls observed and future retreat of Smith, Pope, and Kohler glaciers

Calving cycle of the Brunt Ice Shelf, Antarctica, driven by changes in ice shelf geometry

Information for

External links