海洋学および海洋研究ジャーナル
オープンアクセス

概要

Tracer Transport and Exchange Processes in the Baltic Sea 2000-2009

Dargahi B, Cvetkovic V

In this work we study the exchange processes in the Baltic Sea during a 10-year period (2000-2009). The study is based on numerical simulations of the hydrodynamics that are verified by salinity and temperature data. A particle tracking approach is used for characterising transport and exchange processes. Inert particles are released at different rates ranging from 100 to 5000 particles at durations ranging from 10 days to 10 years with the purpose of quantifying the inter-exchange processes between the Baltic Sea sub-basins and to estimate arrival times and pathways of particles released from the major rivers. The Gotland basins are the major contributors to the baroclinic exchange process in the Baltic Sea. There is evidence in support of notable mixing of the deeper waters of the Western Gotland Basin with the sub-surface waters of the Gulf of Finland. The transport processes in the Bornholm and Arkona basins are both advective and diffusive driven by the interacting flows of the northern basins of the Baltic Sea and the North Sea. The various sills and channels play a significant role in controlling the exchanging processes of the sub basins of the Baltic Sea. Two relative measures (indicators) are introduced for quantifying internal exchange between major basins and internal distribution between basins of tracers discharged by eleven major rivers. The Sea of Bothnia is found to be the major collector basin and the Bornholm Basin the major diffusor basin of the Baltic Sea. The surface waters of the rivers mix internally with the mixing and pycnocline layers. The Gulfs of Finland and Riga, and the islands of the Archipelago Sea are probably the most vulnerable regions from an ecological point of view. The worst scenario for river-borne pollutants is a combination of short travel time and maximum travelled path; rivers of Vistula and Oder fall into this category.