The overall objective is to understand the role played by the sea ice in the energetics of the Greenland Sea system as a whole, and in the specific ice-ocean interactions involved in the process of deep convection in the winter Greenland Sea with its attendant sequestration of carbon dioxide.
To accomplish the overall objective it is necessary to investigate the Greenland Sea on two scales: Basin-wide studies, to determine the large-scale role of the ice cover, and Mesoscale studies in the region of the Odden ice tongue, Boreas Basin and centre of Greenland Gyre, to determine the mechanisms by which sea ice is involved in deep convection in winter, and to estimate CO2 uptake through cooling, convection and biological fixation.
On the basin-wide scale the programme will study:
* the seasonal extent and variability of sea ice;
* the dynamics of the ice;
* its mass flux;
* the exchanges of fresh water and heat between the ice and the upper ocean;
* large-scale air-sea energy interactions in the region; (vi) carbon chemistry; and
* spring bloom dynamics.
This will be done using:
* satellite remote sensing techniques to monitor ice extent, concentration, tupes and velocity;
* the physics of deep convection and its relationship to air-sea-ice interaction mechanisms;
* CO2 uptake during convection events and surface cooling; (iv) the air-sea fluxes of momentum, moisture and heat;
* aerosol concentration and composition; and
* the dynamics of the spring plankton bloom and its impact on CO2 sequestration.
This will be done using:
* direct shipborne measurements by acoustic and oceanographic sensors of the nature and structure of convective plumes and/or chimneys;
* shipborne measurements of the carbon system and carbon dioxide absorption in the convection region;
* airborne and satellite remote sensing of young ice variability in the convection region;
* bringing together of experimental and modelling results in a synthesis of the convection process and its climatic role.
The approach on two scales enables the two ways in which sea ice contributes to the energetics of the Greenland Sea to be assessed in an integrated programme. On the large scale, most of the sea ice in the Greenland Sea enters from the Arctic Basin via Fram Strait, and contributes a fresh water flux at a range of latitudes to the surface waters. It also affects ocean-atmosphere energy exchanges. The large scale programme will map the flux of ice into the greenland Sea, its rate of melt, and energy exchanges in the ice-covered zone, using satellite remote sensing for extent and type; moored and mobile sonars for thickness; shipborne cruises for energy exchanges; and an extensive modelling programme to integrate the results into large scale ocean-atmosphere models.
Some sea ice in winter also forms within the Greenland Sea itself, and the salt flux associated with rapid ice growth is thought to be a critical factor in the onset of deep convection, which is a vitally important process from a climatic point of view since it leads to carbon dioxide transport into the deep ocean and to renewal of the deep waters themselves. The region where this interaction occurs has been identified as the Odden ice tongue in the mid-latitude Greenland Sea. This will be studied by an intensive shipborn programme throughout the winter and spring period, using acoustic and float techniques to locate and measure the plumes themselves, hydrographic surveys to measure the impact of the convection on ocean structure, biological sampling to estimate carbon fluxes, and finer resolution remote sensing to examine the sea ice changes which occur concurrently with the convection process.
Funding SchemeCSC - Cost-sharing contracts
CB3 9EW Cambridge