Istanbul 5th March 2010Efficient downscaling to coastal sea using the

unstructured finite volume model MIKE 3 – applications in the Ligurian Sea and for Danish Belts

Jacob V Tornfeldt Sørensen, DHI

MedGOOS Half-day Seminar 2010

Step I :

• Bathing water analysis

• Scenario modelling (LIP)

Step II :

• Operational forecasting

Ligurian coastal sea 3D model (in colaboration with INGV)

Recent Experiences

User : Agenzia Regionale per la Protezione dell'Ambiente Ligure (ARPAL)

Model forcing :

• MFS boundaries of T, S, u, v and surface elevation

• Tides and inverse barometer effect imposed at the open boundaries

• Atmospheric forcing from BOLAM

Ligurian coastal sea 3D model

Recent Experiences

500 km

Fehmarnbelt Fixed Link

Recent Experiences

• The largest fixed link in Europe

• 20 km• Bridge or tunnel• 4.4 - 5.1 billion EUR• Danish-German agreement

September 2008• Excepted opening in 2018

Denmark

Germany

Recent Experiences

Recent Experiences

Blocking Blocking • Water Exchange of the Water Exchange of the Baltic SeaBaltic Sea• Ecology of the Baltic Ecology of the Baltic sensitive to salinitysensitive to salinity• Cod FisheryCod Fishery

Darss Bothnian Bay

Stolpe

Channel

Gotland Deep

Bothnian Sea

Baltic

Sea

Environmental Concern, (Permanent Effects)

Dredging SpillDredging Spill• Shading of Macro AlgaeShading of Macro Algae• Impact on MusselsImpact on Mussels• Fish MigrationFish Migration• BirdsBirds• Marine MammalsMarine Mammals

Environmental Concern, (Temporary Effects)

Key Issues

• Boundary conditions

• Internal Downscaling

• Consistancy calibration of coarse model data

Downscaling

Key Issues• Boundary conditions

– Regional basin and mesoscale circulation– Tidal elevation and inverse barometer effects– Numerical implementation (e.g. Flather, interpolation

constraint)

Downscaling

MIKE 21 model setup

Mercator Oceanmesoscale model

DHI Gulf of Mexico model

Downscaling

Key Issues• Internal Downscaling

– Numerical method allowing gradual increase in resolution (e.g. flexible mesh finite volume)

– Resolution and bathymetry prererably consistent to coarse model at and near open boundary

– Include model features of importance for local scale modelling (e.g. mass conserving F/D, structures, wave current interaction and process modules)

Downscaling

Ligurian coastal sea 3D model

Downscaling

Resolusion ~ 500m~ 500m

MIKE 3 HD FM

• Bathymetry consistency

• Consistent resolution

• Smooth downscaling

Downscaling

Increased flow resistance and increased mixing

DownscalingCombination of:

- Field measurements- Physical model experiments- Detailed CFD analysis

CFD will supplement and extend the data from the physical model experiments

Parameterisation of flow resistance and mixing

Local high resolution oceanographic MIKE 3 FM model

Downscaling additions

Downscaling additions

• Skillful regional scale models exists• Basic downscaling technology and

methodology exist• Every case still needs careful analysis and

hard work

• Streamline approach via user interface• Advance local scale data assimilation• Further improvement of boundary condition

formulation• Improved computational performance

• Conclusion and next steps

Thank you for your attention

Further information:

jts@dhigroup.com