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1
Content available remote Morphologic and hydrodynamic conditions of Hel Peninsula’s abrasion in the Kuźnica region (southern Baltic)
Łęczyński L., Chlebus N., Grusza G., Jędrasik J.
Oceanological and Hydrobiological Studies
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2007
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Vol. 36, No.2
21-37
EN
The purpose of the presented paper is the identification and assessment of causes of intensive abrasion in the open coastline of the Hel Peninsula and the effect of countermeasures. Numerical modeling of nearshore hydrodynamics, topographic analysis and field measurements were carried out. The Baltic Sea hydrodynamic model, a model of wave-induced nearshore circulation and the wave model SWAN were employed. 3D hydrodynamic modeling resulted in the become visible that fields of shear bottom stresses as well as bottom currents depended on atmospheric forcing and depth. A correlation between bottom stresses and topography was obtained. The results of modeling of the nearshore hydrodynamics demonstrated a dominant role for alongshore sediment transport. The magnitude of both cross- and alongshore wave-induced currents strongly depended on wave height gradient, which was significantly greater in storm periods. During storms, sediment transport occurs also in the cross-shore direction.
2
Content available remote Assimilation experiments in the Gdansk Basin (the south-eastern Baltic): How useful are the sea level data from coastal tide gauges for modelling of hydrophysical fields?
Jankowski A., Jędrasik J.
Oceanological and Hydrobiological Studies
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2007
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Vol. 36, No.4
105-128
EN
In the Baltic modelling research, assin.ilation techniques were developed with advance. They were-concerned to model assimilated basic parameters and observed them directly. In present paper, the most important was the assimilation of surface information and its projection deep into temperature and salinity fields. In oceanic investigations altimetry viewed from satellite was the sea level changes projected far inside and predetermined surface-to-subsurface correlations. To obtain improved modelled hydrophysical fields, sea level variations measured at coastal gauges and efficient data assimilation were taken into account. A data assimilation algorithm has been developed and used in conjunction with a three-dimensional baroilinic model of the Baltic Sea. It was based on a time and space weighted nudging technique. The sea level data were inserted continuously by updating the model solution every time step. Several sensitivity experiments with different values of time and spatial weighting scales were performed. In first series of experiments, only sea level data (SL) were assimilated. In the next simulations, seawater temperature (SWT) and seawater salinity (SWS) related directly to SL were assimilated. To evaluate the effectiveness of the assimilation scheme, modelled sea level series and vertical profiles of seawater temperature and salinity in selected coastal gauges in the Gdansk Basin were examined. Evidently low but statistically essential correlation coefficients indicated nonlinear character of vertical mixing and transfer processes. Decreasing errors obtained while comparing the model results to a control case without assimilation confirmed a real transfer of surface information deep and usefulness of such approach in modelling.
3
Content available remote Validation of hydrodynamic part of the ecohydrodynamic model for the southern Baltic
Jędrasik J.
Oceanologia
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2005
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No. 47 (4)
517-541
EN
The first part of the Baltic Sea ecohydrodynamic model, based on the Princeton Ocean Model (POM), was validated by long-term observations of sea level, salinity and water temperature fluctuations. The modelled sea surface temperature (SST) fields were also compared to satellite images - satisfactory correlation coefficients were obtained. The model bias and efficiency coefficients of the modelled variables in relation to the observed values were determined. The quality of model simulations in relation to measured values was estimated with respect to spatial and seasonal variability in shallow and deep coastal waters as well as in the open sea. The results indicated the high quality of simulations by the hydrodynamic model.
4
Content available remote Ecohydrodynamic model of the Baltic Sea. Part 2. Validation of the model
Jędrasik J., Szymelfenig M.
Oceanologia
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2005
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No. 47 (4)
543-566
EN
The ecohydrodynamic model for the Baltic Sea consists of two interacting parts: one describes the hydrodynamics of the water (3HD), the other organic matter production and destruction (ProDeMo). The results of the simulation were validated. The modelled processes were compared with direct observations, which demonstrated the recurrence of cycles, from the spring diatom blooms through the summer depletion of nutrient salts and algal blooms, to autumn blooms of diatoms and the subsequent destruction of organic matter, and intensified mineralisation of detritus in winter. Calibration yielded a set of coefficients complementing the algorithm of equations describing the production and destruction of organic matter in the coastal zone. Verification of the model has demonstrated that in multi-year simulations it is stable and also that it follows the laws of conservation of mass and energy. The third procedural stage of the model investigation was validation, in which statistical measures in the form of bias, correlation coefficients and effectiveness between simulations and observations not used in calibration describe the quality of ecohydrodynamic modelling in southern Baltic Sea waters.
5
Content available remote Ecohydrodynamic model of the Baltic Sea. Part 1. Description of the ProDeMo model
Ołdakowski B., Kowalewski M., Jędrasik J., Szymelfenig M.
Oceanologia
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2005
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No. 47 (4)
477-516
EN
The ProDeMo (Production and Destruction of Organic Matter Model), a 3D coupled hydrodynamic-ecological model, was formulated and applied to the whole Baltic Sea and the subregion of the Gulf of Gdansk. It describes nutrient cycles (phosphorus, nitrogen, silicon) through the food web with 15 state variables, oxygen conditions and the parameterisation of water-sediment interactions. The present version of the model takes two groups of phytoplankton - diatoms and non-diatoms - as well as zooplankton into consideration. It covers the flow of matter and energy in the sea, including river discharges and atmospheric deposition. Numerical applications are embedded on a 1 NM grid for the Gulf of Gdansk and a 5 NM grid for the Baltic Sea. Since the model results largely concur with observations, the model can be regarded as a reliable tool for analysing the behaviour of the Baltic ecosystem. Some examples of the spatial-temporal variability of the most important biological and chemical parameters are presented. The model results are compared with those of other modelling research in the Baltic Sea. Both the ProDeMo model algorithm and its computing procedures need to be further developed. The next version should therefore enable more phytoplankton groups to be defined, for example cyanobacteria, which are able to take up molecular nitrogen from the atmosphere (nitrogen fixation). Additionally, the sediment phase should be divided into active and non-active layers.
6
The water exchange in estuarine lakes of the southern Baltic Sea as on the Gardno Lake example
Jędrasik J., Cyberski J.
Oceanological Studies
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2000
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Vol. 29, No. 3
43-66
EN
The study of the Lake Gardno uses methodology that enables to estimate a magnitude of the sea inflows, their conditioning and timing as well as frequencies of their occurrence in lake estuaries. A three dimensional hydrodynamic model was applied to the linked regions of the Baltic Sea and the Gardno Lake. The quantitative estimates allow verifying the previous calculations of the water balance including long term changes.
7
Content available remote Procesy wymiany wód w jeziorach przybrzeżnych południowego Bałtyku na przykładzie jeziora Gardno
Cyberski J., Jędrasik J.
Inżynieria Morska i Geotechnika
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2000
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nr 6
319-324
PL
Zagadnienie wymiany wód oparte na trójwymiarowym modelu hydrodynamicznym, obejmującym system jeziora przybrzeżnego z przetoką oraz dopływającą rzeką Łupawą i napływ wód morskich. Informacje o częstotliwości wlewów, ich wielkości i czasie wystąpienia, adwekcji soli i ciepła. Skuteczne rozwiązania związku jeziora estuariowego z morzem
EN
Water exchange processes in coastal lakes of south Baltic Sea for Gardno lake. Problems of water exchange in three-dimensional hydrodynamic model including system of coastal lake with channel, inflow of Łupawa river and sea waters. Information including frequency of inflows, its capacity and time of occurrence, salt and heat advection. Effective solution for interaction between astuary lake and the sea.
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