Report from Bergen Polar Ice Group Workshop Tuesday, 30. January 2007;

This was the first gathering in what we hope will be 'The Bergen Polar Ice Group' that has been initiated from the Geophysical Institute, but will also be integrated with the Bjerknes Centre activities. Ice people are in many camps, so this is, and was, on Tuesday 30. January, a good way to meet. We were about 20-25 people during the day. There are no current plans for a new workshop, but if our proposal is funded we will gather every 6 months or so to reflect recent activity. The next workshop will be fully coordinated with Research Group 3 'Ocean-ice-atmosphere processes' at the BCCR, but everybody will be welcome.

The discussion ended up with some 'real' things to work on;

a) Radiation in general, as NCEP and ERA40 results are off by as much as 70 W/m2 in places. Check how these compare with data from Hopen and Bjørnøya in the Barents Sea. In this comaprison satelite data are also very relevant.

b) For BCM we, or Mats, suggest splitting the radiation balance in the grids into land, open water, and sea-ice components, as this is will likely give more realistsic treatment. Other than that there are no 'special' wishes for variables to be measured in future sea-ice field campaigns.

c) Heat fluxes in leads are likely highest (per m^2) in 1-3 km leads. This will require a fully coupled model (air/sea/ice) with a very high resolution to be treated properly, but ways to get around this are planned in the POCAHONTAS project. Preferred sampling stategy for upcoming IPY BIAC/CARE cruise was discussed, and agreed. Simulations should be give an effective turbulent heat flux coefficient in dependence on effective lead width, and thereby be applicable in large scale models once they resolve lead width.

d) Ocean boundary layer data are available from 1 m level ice (Van Mijenfjorden) and drift ice (Whalers Bay) that could be used to validate ROMS sub sea ice boundary layers. Nobody has looked into this yet. More data will be gathered. There is almost no drag data in the vicinity of ridged floes. It is critical to observe oceanic and atmospheric drag at the same place, as their ratio (Cda/Cdw) determines the ice drift.

e) For ROMS model runs underway; all fluxes (heat, salt, mass) should be saved so that validation can take place.

f) Field plans for upcoming season were discussed, suggestion to measure light below ice as this is a parameter that is of great impoartance for biology and climate change effect studies. This might be difficult and could be computed from ice salinity and temperature based on lab experiments however.

Improvements of sea ice model dynamics/thermodynamics was discussed. At present, "bad" forcing (radiation budgets) is believed to be a bigger source of model error, and should be adressed first. Validation of even a 'simple' model is difficult as usually sea ice concentration is the only avaible data. Ice thickness distribution measurements, and ice drift data are sparse, but some exist from Storfjorden last season. In Storfjorden also SAR images from the period 1997-2005 may be used to evaluate drift. A study of recent RADARSAT products would be very useful. Ice strength and drag equations might improve models in future. Some theoretical approaches exist, but likely have to be properly worked out for different scales. Also here are ice thickness observations urgently required. Validation from the Amundsen Sea indicates that forcing and ice dynamics also limits results in Antarctica.


Bergen Polar Ice Group Workshop
Geophysical Institute, University of Bergen Workshop intention We will have short presentations (15 minutes + 15 minutes discussion) on aspects of the geophysics of sea ice on different scales, in order to Exchange knowledge about atmosphere-ice-ocean interaction processes. Outline modelling and observational problems and focal points of research. Discuss future challenges, capabilities, plans

09:00-10:30 Sea ice in large scale models I
09:00-09:30 Overview of sea ice processes from the micro- to the geophysical scale (S�nke Maus)
09:30-10:00 Sea ice in the Bergen Climate model (Mats Bentsen)
10:00-10:30 Sea ice in ROMS (Enrique Curchitser/ Paul Budgell)