Annu Oikkonen University of Helsinki

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Annu OikkonenUniversity of Helsinki

• Mesoscale dynamic-thermodynamic modelling of sea
  ice

Supervisor Prof. Matti Leppäranta
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Mesoscale dynamic-thermodynamic modelling of sea
ice

• The coupling of dynamics and thermodynamics is
  very important in regional and global climate
  research for ice climatology, air sea fluxes
  and ecology of ice-covered seas, and also in
  short term questions for forecasting of ice
  drift, ice loads, and transport and dispersion of
  pollutants, in particular oil spills.
• The project aims at developing a next generation
  dynamic-thermodynamic mesoscale (100 km) sea ice
  model with established scaling laws from the floe
  size scales to basin scales.
• The problems to be investigated are the
  mechanical behaviour of ice in different scales,
  iceocean interaction, and ice thickness
  redistribution. The key feature in the scaling is
  a proper understanding of the rheology of sea ice
  and its dependence of ice thickness, compactness
  and state of motion. Also downscaling of the ice
  stress into the inside-floe scales will be
  considered

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• The Baltic Sea is the main study region.
• The product of the project will be used for
  basic research in earth and environmental
  sciences, ice engineering applications for
  scaling of the stresses, short-term ice
  forecasting of oil spills, and in regional ice
  climate research. Also the findings of the
  project may be utilised in developing the sea ice
  code in global climate models.
• I concentrate on ice - ocean interaction, that
  is presently oversimplified in mesoscale models
  and a more advanced treatment is needed
• Both field work and modelling

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R.V. Aranda in the Bothnian Bay, 1.-12.3.2009
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• Turbulence measurements of velocity (8 Hz) ,
  salinity and temperature (1 Hz)
• CTD profiles
• ADCP current profiling (0-10 m)
• Ice drift from Aranda GPS

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Ice drift in Station 2 and 3

• In S3 ice drift was very close to free drift
• - Deviating right from the wind direction, drift
  speed 1-2 of wind speed

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• Ice velocity spectrum
• In the Baltic Sea synoptic time scales
  dominating
• Tidal and inertial signals significant in the
  oceans

Aranda drift
Drifting buoys in the Sea of Okhotsk, Japan
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Thank you!