Task Leaders: Lars Henrik Smedsrud (BCCR), Frank Nilsen (UNIS)

The work in this task consists of two distinct parts: (i) co-located investigations of the atmosphere, sea ice and ocean using innovative instrumentation and (ii) turbulence-resolving boundary layer modelling. The experiments will be carried out from open ocean conditions over warm Atlantic Water in Whalers Bay through the marginal ice zone and into the central Arctic ice pack in April 2007 and 2008. The atmospheric boundary layer will be observed by use of small unmanned meteorological drones for repeated profiling coupled with direct turbulent flux measurements. Turbulence in the ocean boundary layer will be observed with modern high resolution profiling instruments. Coupled atmosphere-iceocean modelling on turbulence scales will be performed with an advanced Large Eddy Simulation code LESNIC (NERSC, Bergen), which is an implementation of a novel dynamic large-eddy simulationtechnique with essential microphysics and ice dynamics. The modelling will address interactions between the turbulent processes and thermally heterogeneous surface with dynamic ice formation. Problems in focus are the role of boundary-layer coupling, turbulence self-organization, turbulencebreeze interactions, salt release, cloudiness, short surface waves. The model data will serve to optimize measurements, to create a three-dimensional view of the ongoing processes, and to aggregate fluxes for large-scale modelling.

WP 3.2 Arctic ice cover and ocean changes. (Frank Nilsen)

Spatial surveys will be performed from Whalers Bay into the ice pack over the deep Arctic Ocean towards the North Pole in parallell with the process studies in WP3.1. Ice thickness data will be collected using EM-bird from helicopter. Observations of snow cover, ice thickness, snow and ice density, temperature and salinity will be taken at the CTD stations, which will allow analyses of ice freeze and melt, the halocline and spreading of Atlantic Water. This activity will contribute to the international circumpolar IPY survey of the Arctic Ocean similar to the Soviet SEVER airborne programme in the 1970s. The data analysis will be tightly integrated with surveys performed by international collaborators in other areas and seasons.  The plan assumes availability of KV Svalbard 14 days ex Longyear in winter/spring 2007 and 2008. This will be decided in 2006 upon separate application to "Samarbeidsutvalget for havforskning" organized by the Norwegian Research Council. All logistics except shiptime are included in the budget based on realistic estimates including helicopter time. The WP can therefore be executed as planned independent of any other funding agencies. However, the development of international and national planning and coordination under IPY and funding of project proposals of collaborators, e.g. for placement of helicopter fuel depots on the ice by TwinOtter, may open new opportunities for improved data recovery.

The field work performed as part of the Norwegian contribution will cover a geographical area that complements the investigations of international collaborators. Our access via Whalers Bay in wintertime gives unique opportunities for studying extreme conditions ranging from open water (such as may occur over larger parts of the Arctic in this century) to interior ice, and mechanisms for spreading of Atlantic Water into the central Arctic. The sea ice and ocean survey is conducted in wintertime in an area which is expected to have good coverage from icebreakers in summertime during IPY thus allowing detailed studies of the seasonal evolution of sea ice freezing and melting processes and vertical distribution of freshwater. There is tight international coordination of this survey extending beyond CARE to already funded activities in DAMOCLES and NPEO and several internationally approved IPY proposals and national programs.