Hydrodynamics and variability of hydrological parameters Hydrodynamics and variability of hydrological parameters in the Baltic Sea
- modelling and numerical simulations 1

A fully three dimensional s - level model based on the Princeton Ocean Model code (Mellor, 1993) was applied to study wind- and density-driven water movements in the Baltic Sea. The model domain comprises the whole Baltic with its main basins: the Gulf of Bothnia, the Gulf of Finland, the Gulf of Riga, the Belt Sea, Kattegat and Skagerrak. Bottom topography of the Baltic Sea used in the model is based on data from Seifert and Kayser (1995). (Figure 1). At the open boundary in Skagerrak the simplified, radiation type, boundary conditions were applied. Model, with two versions of horizontal resolutions of ~ 5 km and ~ 10 km and with 24 s - levels in vertical, allows to reproduce main features of currents and thermohaline fields. (Figure 2).

An application of the s - level model to simulate circulation and stratification as an response of of stratified sea waters to atmospheric forcing in the shallow sea basin with the complicated bottom topography as it is in the case of the Baltic Sea, may be interesting also for comparison with results of z - level models (based on Bryan-Cox-Semtner model (cf. Killworth et al., 1991) ), commonly used in other investigations (e.g. cf.: Krauss and Brügge, 1991; Lehmann, 1995; Elken, 1996; Meier et al., 1999; Lehmann and Hinrichsen, 2000).

To demonstrate the utility of the POM code for the Baltic Sea conditions, model was applied to simulate wind - induced variability of hydrological parameters in the coastal area at the Polish Baltic coast The calculations shown that the model yields results share many features in common with a coastal upwelling, a phenomenon, frequently observed in coastal regions of the Baltic Sea (cf. Bychkova and Victorov, 1987; Bychkova et al, 1988; Urbański, 1995; Krężel, 1997). Some results are reported in the enclosed file in pdf format (File in PDF format). In the next enclosed file in pdf format (File in PDF format 2) the preliminary results of an application of the POM code to hindcast modelling of real upwelling situation at the Polish Baltic coast (cf. Malicki and Miętus, 1994) were presented.

References
Bychkova I.A., and S.V. Viktorov, 1987, Elucidation and systematization of upwelling zones in the Baltic Sea based on satellite data., Okieanologiya, XXVII, 218-223 (in Russian).
Bychkova I.A., S.V. Viktorov, and D.A. Shumakher, 1988, A relationship between the large - scale atmospheric circulation and the origin of coastal upwelling in the Baltic Sea Meteorologiya i gidrologiya, 10, 91-98 (in Russian).
Elken, J., 1996, Deep water overflow, circulation and vertical exchange in the Baltic Proper, Estonian Marine Institute Report Series, No. 6, Tallinn, 91 pp.
Killworth P., D. Stainforth, D.J. Webbs, and S.M. Peterson, 1991, The development of a free-surface Bryan-Cox-Semtner ocean model., J. Phys. Oceanogr., 11, 415-433.
Krauss W., and B. Brügge, 1991, Wind-produced water exchange between the deep basins of the Baltic Sea, J. Phys. Oceanogr., 21, 373-384.
Krężel, A., 1997, Recognition of mesoscale hydrophysical anomalies in a shallow sea using broadband satellite teledetection methods, Wydawnictwo Uniwersytetu Gdańskiego, Gdańsk, 173 pp. (in Polish).
Lehmann A., 1995, A three-dimensional baroclinic eddy-resolving model of the Baltic Sea, Tellus, 47A, 1013-1031.
Lehmann A., and H.-H. Hinrichsen, 2000, On the wind driven and thermohaline circulation of the Baltic Sea, Phys. Chem. Earth (B), 25, No. 2, 183-189.
Malicki J., and M. Miętus, 1994, Climate, [in:] The Baltic Sea Atlas, A. Majewski and Z. Lauer (Eds.), IMGW, Warsaw, 60-69, (in Polish)
Meier H.E.M, R. Döscher, A. C. Coward, J. Nycander and K. Döös, 1999, RCO - Rossby Centre regional Ocean climate model: model description (version 1.0) and first results from the hindcast period 1992/93, SMHI, Reports Oceanography, No. 26, 102 pp.
Mellor, G. L., 1993, User's guide for a three-dimensional, primitive equation, numerical ocean model, Atmospheric and Oceanic Sciences Program, Princeton University, 35 pp.
Seifert, T., and B. Kayser, 1995, A high resolution spherical grid topography of the Baltic Sea, Meereswissenschaftliche Berichte, No. 9, Institut für Ostseeforschung, Warnemünde, 72-88.
Urbański J., 1995, Upwellings along the Polish coast of the Baltic Sea, Przegląd Geofizyczny, XL, 141 - 153 (in Polish).

Footnotes:

1 This research was supported by project No. 6 PO4E 020 15 from the Polish State Commitee for Scientific Research untitled: Model of dynamics of coastal waters in vicinity of the Polish Baltic coast. Role of vertical movements (up- and downwelling) in water exchange. Project coordinator and chief performer: Andrzej Jankowski, Institute of Oceanology of PAS, Sopot, Poland; E-mail: jankowsk@iopan.gda.pl

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On 07 Dec 2000, 15:25.