物理海洋学名词-B 49

Glossary of Physical Oceanography and Related Disciplines

Steven K. Baum Department of Oceanography Texas A&M University

May 26, 2004

 

BALTEX Acronym for the Baltic Sea Experiment, a GEWEX project to study coupled hydrological processes between complicated terrain, sea and ice and the atmospheric circulation to determine the energy and water budgets of the Baltic Sea and related river basins. The scientific objectives are:
• to explore and model the various mechanisms determining the space and time variability of energy and water budgets of the BALTEX area and its interactions with surrounding regions;
• to relate these mechanisms to the large–scale circulation systems in the atmosphere and oceans;and
• to develop transportable methodologies to contribute to research in other regions.
[http://w3.gkss.de/baltex/baltex home.html]
Baltic Current  See Kattegat.
Baltic Operational Oceanographic System (BOOS) A cooperative endeavor among national government agencies in the countries surrounding the Baltic Sea responsible for the collection of observations, model operations and production of forecasts, services and information for the marine industry, and public and other end users. BOOS is a regional Task Team under EuroGOOS.
BOOS will be implemented from 1999–2003 by the accomplishment of nine projects:
• optimizing the existing operational observing network;
• use of remote sensted radar and satellite data;
• an operational mesoscale analysis system called PRODAS;
• optimization of existing models and coupled models;
• ecological modeling;
• study of harmful algae blooms via HABWARN;
• development of an anthropogenic load model;
• an assessment of the current state of the Baltic environment; and
• development of Info–BOOS.
[http://www.boos.org/]
Baltic Sea A dilution basin type of mediterranean sea that is connected to and experiences limited, intermittent water exchange with the North Sea. It comprises several parts separately known as the Gulf of Bothnia, the Aland Sea, the Gulf of Finland, the Gulf of Riga, Kattegat and Skagerrak. It has a mean depth is about 57 m, an area of about 370,000 km2, and a volume of about 20,000 km3, and is one of the largest brackish water bodies in the world. About 17% of its area is shallower than 10 m. The Baltic Sea depression is essentially a long fjord in the north–south direction (1500 km) with an average width of 230 km. The topography divides it into a series of relatively deep basins, with maximum depths ranging from 105-459 m.The Baltic has a positive freshwater balance with an annual river runoff of 440–480 km3, or about 2.2% of the volume. The runoff is usually maximum in May and minimum in January or February. A permanent salinity stratification results in a transition layer at 65–75 m. The residence time is on the order of several decades. The difference between precipitation (640 mm) and evaporation (500 mm)
adds another 60 km3 per year.The circulation in the Baltic Sea is mainly driven by three forces:
• wind stress;
• horizontal density differences due to freshwater inflow from rivers and saline water inflow via the Danish Straits; and
• sea level inclination from the Danish Straits towards the interior.
On average, sea level rises about 25 cm from the Danish Straits towards the Gulf of Bothnia due to the river runoff.
If not interrupted by wind–driven currents, a continuous inflow of saline water from the Skagerrak forms the deep water of the Baltic. It is estimated that 740 km3 of saline water enters the Baltic per year. The inflow enters through the Great Belt (65%), the Sound (25%) and the Little Belt (10%).

After passing through these, the saline water passes over the shallow Darss Sill (18 m), crosses the Arkona basin,flows through Bornholm Strait into the Bornholm Basin, and finally flows through Stolpe Channel into the Gotland Basin. The value of σt increases from less than 5.0 in the Gulf of Finland to more than 25.0 in the Skagerrak. See Segerstrale [1957], Zenkevitch [1963], Rodhe [1998] and Stigebrandt [1999] 

 

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