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Current Research Programmes


Sea Ice and Polar Oceans

Modelling

Group leader: Danny Feltham

The sea ice and polar oceanography modelling group focuses on the development of improved understanding and theoretical representation of physical processes that play a pivotal role in the balances of heat, mass, and momentum in the polar seas. The approach is to use small-scale and/or highly idealised process studies, calibrated and tested with a wide range of observations, to generate understanding of the controlling processes. Typically this work involves both paper-and-pen fundamental studies and numerical modelling. Example processes are the role of melt ponds in controlling the summer melt of Arctic sea ice, the role of anisotropy in controlling the momentum and mass budgets of sea ice, and the role of frazil ice in controlling the mass balance of sea ice and ice shelves. These process studies allow us to develop simplified representations, known as parameterisations, of the relevant processes that can be incorporated into the sea ice component of climate models. We use a stand-alone (forced) climate sea ice model to allow us to investigate the impact of newly-developed physics on regional and pan-Arctic simulations of the sea ice cover.


Programme list:

Anisotropic sea ice mechanics

Alexander Wilchinsky, Danny Feltham
Sea ice is a layer of frozen sea water covering vast areas of the polar oceans.  Sea ice affects the climate due to its impacts on the heat, mass, and momentum budgets of the atmosphere and ocean. In order to simulate sea ice properties such as its thickness and concentration, it is necessary to model how sea ice moves and deforms in response to stresses exerted by the wind and ocean. This project focuses on incorporating existing knowledge of the way sea ice fractures, slides, breaks up, and piles up under different failure modes, into one model describing the response of sea ice to different stress conditions. This involves modelling the impact of leads, which are long, narrow weakness in the ice cover formed during previous deformation events, on the mechanical properties of the ice cover.  Read more... 

Impact of a new anisotropic rheology on the Arctic sea ice

Michel Tsamados, Danny Feltham
The Arctic sea ice cover is a vast frozen layer of water covering a surface larger than Europe in the winter. In the last three decades the summer ice extent has been dramatically shrinking at an average rate of 12% per decade, reaching its lowest recorded extent in the summer of 2007.  In addition, the ice is thinning at an even faster rate. Climate change experiments using Global Circulation Models (GCMs) have been shown to underestimate these trends. Uncertainty in sea ice mechanics could account for a substantial fraction of the discrepancy between GCM predictions and observations. We have developed new theory accounting for the impact of observed, oriented failure zones in the sea ice cover on sea ice mechanics. This project has implemented an anisotropic model of sea ice mechanics into the sea ice component of a climate model and examined its impact on sea ice simulations. Read more  

Implementation of melt ponds into the CICE sea ice model

Daniela Flocco, David Schroeder, Danny Feltham
Sea ice, frozen sea water, covers large areas of the Arctic and Southern Oceans and plays an important role in regional and global climate. Changes in sea ice represent one of the largest uncertainties in the prediction of future temperature increase. Studies show that the observed discrepancy between sea ice model predictions and observations is at least partly due to limitations in the existing model physics. In current climate models melt ponds are not explicitly represented. Melt ponds form on sea ice during the summer due to melting of snow and/or the upper layer of sea ice. Because the albedo of melt ponds is lower than the surrounding ice, they preferentially absorb solar radiation leading to further melt. We have incorporated a physically based melt pond scheme into the CICE sea ice model, which simulates the formation, evolution, and refreezing of melt ponds. Our simulations demonstrate the impact of melt ponds on sea ice thickness and extent. Read more  

The mixed layer over the Antarctic continental shelf

Alek Petty (PhD student), Danny Feltham, Paul Holland (CASE supervisor)
The main aim of this project is to understand the cause of the variability of continental shelf water properties (temperature and salinity) at the sea bed around Antarctica. The Weddell shelf sea is believed to be composed of cold salty water in winter, leading to the production of Antarctic bottom water (which plays an important role in the global ocean circulation). The Amundsen shelf sea however appears to allow warm ocean currents to flood onto the shelf, potentially leading to ice shelf thinning, ice shelf collapse and thus the potential for sea level rise. To try and understand the cause of this regional difference, we have developed a continental shelf, mixed layer model coupled to a simple sea ice model. We are using this model to study the importance of atmospheric conditions (e.g. air temperature, wind speed etc) in determining the regional variation of shelf water properties. Read more  

Jet formation at the sea ice edge

Harold Heorton (PhD student), Danny Feltham, Ann Keen (CASE supervisor
at UK Meteorological Office)
This is a PhD project in collaboration with the UK Meteorological Office. Atmospheric jets are known to form over coastlines. This formation is due to changes experienced by winds blowing from the open ocean to land. Similar changes are experienced over the sea ice edge, and also by the ocean underneath the ice. We are mathematically modelling these jets to improve the understanding of ice dynamics at the sea ice edge. The sea ice edge is currently not represented in large sea ice models. Read more  

Incorporation of frazil ice into a sea ice/ocean model

Nikhil Radia (PhD student), Danny Feltham, Miguel Angel Morales Maqueda
(CASE supervisor oat the National Oceanography Centre)
This is a PhD project joint with the National Oceanography Centre. The aim of this project is to develop a new model of how frazil ice (millimeter-sized crystals of sea water) are formed in regions known as leads and polynyas, which are open water regions in the sea ice cover. Creation, examination and testing of this model has led to improved understanding of the processes controlling new sea ice growth and the ocean mixed layer. Read more  

 

 

Observation

Group leaders: Seymour Laxon and Katharine Giles

Programme list:

Determining sea ice thickness from space-borne radar altimetry

Seymour Laxon, Katharine Giles and Andy Ridout
Knowledge of sea ice thickness and volume are critical to understanding past, present and future changes in the polar ice cover. CPOM has led efforts to determine sea ice thickness from space-borne radar altimeters including ESA’s ERS, Envisat and CryoSat missions.  Read more  

Arctic Ocean circulation from radar altimetry

Katharine Giles, Seymour Laxon and Andy Ridout
As the Arctic ice cover retreats the Arctic Ocean circulation may also change, which could speed up the reduction of the sea ice cover and alter the storage and distribution of freshwater. This, in turn, could affect the large-scale ocean circulation and cool the climate of Northern Europe. CPOM uses satellite data to monitor changes to the sea surface height, which can provide information about the Arctic Ocean surface circulation.  Read more 





Previous Research Programmes


Ice Sheet and Glacier Dynamics

Leader: Prof. A.J. Payne

Programme Background


A suite of models for studying the dynamics of ice sheets, ice caps and glaciers

Project Manager: Prof. Antony Payne, Bristol  

Morphology and dynamics of the Antarctic and Greenland ice sheets

Project Manager: Prof. Jonathan Bamber, Bristol  

Large ice caps dynamics and mass balance

Project Manager: Prof. Julian Dowdeswell, Cambridge  


Earth's Ice Mass Fluxes

Leader: Prof. D.J. Wingham

Programme Background


Antarctic Ice Mass Fluxes

Project Manager: Prof. Duncan Wingham, UCL  

Arctic Ice Mass Fluxes

Project Manager: Dr. Seymour Laxon, UCL


Other


CryoSat Data Processing

Project Manager: Steve Baker, UCL