Model set-up

EGU, General Assembly 2011 , Vienna, Austria, 3 – 8 April 2011

MODELLING OF SALINITY AND TEMPERATURE VARIATION IN

THE BALTIC SEA DURING THE LAST TWO DECADES

S. Miladinova and A. Stips


Model set-up

GETM (www.getm.eu)

Topography 1 nm by 1nm (www.io-

warnemuende.de/topography-of-the-baltic-

sea.html)

Sea level variations at the open boundary

(www.dmi.dk/dmi/tr07-09; www.ioc-

sealevelmonitoring.org)

Runoff from land (different sources )

Meteorological forcing (www.ecmwf.int)

Initial and boundary conditions for salinity and

temperature (Janssen et al. (1999);

nest.su.se/bed)


Model domain

Horizontal grid - 628 x 371 (cells of 1 nm by 2 nm);

25 vertical layers of adaptive terrain-following coordinates;

Time step: 25 s for the barotropic and 750 s for the baroclinic mode;

Calculations are distributed to 48 processes;

The run is carried out on 4 clusters with 12 CPUs;

About 20 CPUs minutes for a month;

25 year run (1986–2010).


Difference between observed and modeled daily mean sea levels at Landsort


Model verification at Anholt station (1986 – 2010)

Correlation coefficient = 0.92RMSD = 2.8Standard deviation = 1.2

Correlation coefficient = 0.95RMSD = 1.5˚CStandard deviation = 1


Model verification at Bornholm station




Model verification at LL7 station




Major Baltic inflow in 1993


Salinity simulation of the major inflow


A minor Baltic inflow in the autumn of 2001


Temperature in the case of minor inflow (2001)


Recent inflow events (2006 – 2008)

Drogden Sill

Darss Sill

Short Info for the inflow events http://www.io-warnemuende.de

barotropic inflow

baroclinic inflow


Bottom and surface salinity at Bornholm during the last 5 years


Mean surface/bottom temperature in comparison to the mean values of the last 25 years

At the surface

At the bottom


Conclusions

The model is capable to reproduce reasonably the Baltic inflow events;

Better calculation of the near bottom temperature in the deep regions is crucial;

Higher inflow activity is detected;

Frequent occurrence of moderate/minor barotropic and baroclinic inflow events ventilate “continuously” the Borholm Deep and the Gdansk Deep;


ACKNOWLEDGEMENTS:

We are grateful to the Baltic Nest Institute, Stockholm University for making available the hydrographic data trough the Baltic Environmental Database.

Special thanks are given to the GETM developers for providing and maintaining the model, and in particular to Richard Hofmeister for developing and implementing the adaptive vertical coordinates.

Info:The monthly mean hydrodynamical model results will be uploaded on the Environmental Marine Information

System (http://emis.jrc.ec.europa.eu)

Documents

Model set-up