Bornholm Deep

Bornholm Deep 233 Gdansk Deep Gotland Deep F rd Deep Landsort Deep Karlsd Deep... 

TABLE 10.1 Estimated Propagation Speed of the Water Penetrated during Some Important Inflow Events between Both Darss Sill - Bornholm Deep (Distance 240 km) and Darss Sill - Gotland Deep (Distance w640 km) Time is Measured between Inflow Event (MBI) at the Darss Sill and Bottom Water Renewal (BWR)... 

Due to the great success of the IBY, the Baltic oceanographers recommended at the conference in Helsinki in 1970 the voluntary continuation of the IBY programme for the subsequent years. The GDR followed this recommendation. In combination with the national monitoring programme covering the Baltic Sea between Fehmarnbelt and Bornholm Basin, the IfM Warnemunde expanded its seasonal cruises to the Gotland Deep... 

Besides MB Is, baroclinic summer inflows of exceptionally warm and saline water affect the deeper layers of the central Baltic Sea (cf. Section 10.5). Such inflows do not fulfill the criteria for MB Is (cf. Section 10.3) but can effectively influence the deep water below the halocline in the Bornholm, Gdansk, and Eastern Gotland Basins (Feistel et al., 2003c, 2004a). 

The intensity of MBls can be estimated during the inflow events by the salinity conditions at the Baltic entrance sills (cf. Section 10.4). The effects of MBls in the central Baltic deep water depends on the density of the inflowing water, the mixing with the ambient water on its way through the Baltic Sea (cf. Fig. 10.1), and the density of the deep water in the various basins. The pathways of the inflowing water propagating from the sills through the Arkona Basin into the Bornholm Basin have been studied in detail by Lass et al. (2005). 

The first deep basin downstream of the entrance sills is the Bornholm Basin (Fig. 10.1). This basin has a maximum depth of more than 90 m and is separated from the next downstream basin by the Slupsk Sill (sill depth 60 m). The buffering properties of the Bornholm Basin play an essential part for the effectiveness of MBls in other central basins. The thermohaline conditions in the Bornholm Basin are also considerably important for the evolution of stagnation in the central Baltic deepwater. In general, there is a frequent inflow of lower amounts of highly saline water that penetrates across the sills into the ArkonaBasin during each baroclinic or weak barotropic inflow event. This water is trapped into the... 

The salinity of the Bornholm Basin below the permanent halocline is a measure for the estimation of the impact of weak inflows on the central Baltic deep water. During periods of low inflow activity, salinity and thus density decreases in the deep water of the Bornholm Basin. Depending on the volume of saline water and its density, inflows below the MBI magnitude — but sometimes even MBIs — fill up only that basin, and the saline water does not pass to a greater extent the Slupsk Sill downstream through the Slupsk Channel into the Gotland Basin (cf. Fig. 10.2). 

Fonselius (1962) started the detailed description of the effects of MBIs in the central Baltic deep water. He identified MBIs studying long-term variations, mainly of salinity in the Bornholm Basin. Fonselius described the dynamic processes between the Baltic deep basins after MBIs, the importance of the Bornholm Basin as buffer basin, and the overflow of the Eastern Gotland Basin in intermediate depths downstream into the Landsort Deep. 

This event initiated a change of the redox conditions in the deep basins, especially the Bornholm and Gdansk Basins which were provided with a supply of oxygenated water. Even the Gotland Deep was free of hydrogen sulfide for a short time following this saltwater inflow event (HELCOM, 1996). 

Heavy metal, pg/g Arkona Basin Bornholm Basin Gdansk Basin Landsort Deep Gotland Basin... 

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