Drogden Sill

The monthly means, however, suggest occasional inflow events, especially in November 

The site (DrS), which is also operated and maintained by RDANH, is located at the southern end of the shallow ( 10 m deep) Drogden Sill at the eastern entrance of the Sound. Table 6.9 shows annual and monthly average values. The technical details are the same as for W26 in the Great Belt, but here we selected the year 2005 because of having additional data from the Arkona Sea in 2005 (see Section 6.3.3). 

The mean magnitudes at Drogden Sill in 2005 are about 50% higher than that at Darss Sill in the same year. The strongest monthly speeds occurred in February 2005 toward the northeast. During several months, the mean speeds at the lower level distinctively exceed 

TABLE 6.9 Annual and Monthly Current Statistics for 2005 at Drogden Sill (DrS) 

3 m differs by almost 80°. In September, outflow toward 36° as usual prevails, on average, at about 3 m depth, whereas only 2.5 m below inflow toward 181° is dominating. In November, the mean values indicate inflow at both levels with a speed of 17 cm/s at 5.3 m depth, which is four times stronger than the near-surface speed at 2.8 m. (4 cm/s). 

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In this section, current measurements from the western Arkona Sea and the Drogden Sill are presented. Table 6.7 gives a summary of the sampling positions and intervals. The sampling locations are shown in Fig. 6.1 with their mooring identifiers. 

Different estimations of the strength of the January 1993 event (cf. Section 10.4.3) led to the reassessment of the intensity. Instead of the mean salinity, Fischer and Matthaus (1996) used the amount of salt q (in Gt = IO kg), entering the Baltic Sea over both the Darss Sill (DS) and the Drogden Sill (DR), as the criterion for the intensity of MBls. On this basis, they recalculated the intensity of 90 events that took place between 1897 and 1976. The new method permitted the quantitative estimation of the strength of MBls using the total salt transport into the Baltic Sea. 

In addition to the criteria GR 1 and GR 2 used for identifying MBls at the Darss Sill, Fischer and Matthaus (1996) developed the following criteria to ascertain inflow days at the Drogden Sill belonging to each identified event ... 

Fischer, H., Matthaus, W., 1996. The importance of the Drogden Sill in the Sound for major Baltic inflows. Journal of Marine Systems, 9, 137-157. 

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