ALBERT

Description: From numerical model simulations, fluxes of volume, heat and salt have been calculated for different hydrographical sections in areas which are important for the deep water exchange in the Baltic Sea. The calculated deep water flow in the Arkona basin is in accordance with independent estimations obtained from profile data. Model results reveal strong seasonal and inter-annual variability in the calculated fluxes. The variability is governed by the prevailing atmospheric conditions. It is found that the strength of the upper layer low saline flow in the Arkona Basin which on average is directed to the west, opposite to the mean wind direction, is compensated by a high saline flow in deeper layers. The upper layer flow is a combination of a flow forced by the fresh water surplus directed to the west, and a wind-driven part. In dependence on the prevailing wind conditions the resulting flow is either increased or decreased. Furthermore, increasing upper layer flow results in an increased lower layer flow in opposite direction. The annual mean flow is weakly correlated with the annual mean runoff to the Baltic Sea. In accordance with the mean circulation, the flow through the Bornholm Channel is on average directed to the east, and south of Bornholm to the west indicating an import of heat and salt to the Bornholm Basin through the Bornholm Channel and an export south of Bornholm. Flux characteristics change further downstream in the Stolpe Channel. The volume flow in the upper layer shows a strong seasonal signal. During autumn to spring the flow is mainly directed to the east, in summer, the flow direction is reversed. Flow in westerly directions is related to increased lower layer flow in easterly directions. On average, the net flow through the Stolpe channel is directed to the east which is in accordance with the mean circulation. Calculated fluxes show high intra- and inter-annual variability with no obvious trend during the simulation period. The variability of the deep water stratification in the deep basins of the Baltic Sea is directly controlled by the changing flux characteristics.

Description: The study aims at the identification of areas in the Baltic Sea from where potential pollution is transported to vulnerable regions. Generally, there is higher risk of ship accidents along the shipping routes and along the approaching routes to the harbors. The spreading of harmful substances is mainly controlled by prevailing atmospheric conditions and wind-induced local sea surface currents. Especially, spawning, nursery and tourist areas are considered high-vulnerable areas. With sophisticated high resolution numerical models, the complex current system of the Baltic Sea has been simulated, and with subsequent drift modeling areas of reduced risk or high-risk areas for environmental pollution could be identified. In a further step, optimum fairways of reduced risk could be obtained by following probability minima of coastal hits or maxima for the time it takes to reach the coast. The results could be useful for environmental management for the maritime industry to minimize the risk of environmental pollution in case of ship accidents.