MARNET Stations

The measured barotropic velocity projected onto the channel axis at the Darss Sill MARNET station reveals a rather Gaussian distribution, while the distributions of both the sea level difference between Viken and Skanoer and the transport derived according to Equation 2.14 differ significantly from the Gaussian distribution. However, the minimum of the wave-controlled and the frictional-controlled transports depicts a quite reasonable Gaussian distribution. 

FIGURE 3.1 Monitoring station network of the IfM in 1980 and of the lOW in 2005, the first IfM buoy station in 1964, and the MARNET stations. Lower right comer bathymetric map of the central Eastern Gotland Basin with positions of the central BMP station (271) and moored subsurface strings between 1993 and 2005 used abbreviations and further details are compiled in Table 3.3. 

At the eastern flank of the relatively shallow and topographically even Darss SiU is the MARNET station Darss Sill (DS, see Chapter 3), where operational ADCP current measurements have been carried out since 2004. This is the region from where the most important proportion of saline and oxygenated water masses from the Kattegat occasionally spreads within the near-bottom layer down the slope into the deep of the Arkona Sea. Table 6.8 shows the annual and monthly means of the year 2005. 

For the MARNET Station Arkona (13°51.72 E, 54°52.98 N), the effective fetch was calculated (see Fig. 7.7). For this purpose, 18 half-lines at a distance of 10° up to the coastline were drawn in a sector of +/-90° around the half-line pointing in westerly direction,... 

FIGURE 7.14 Wave Height Comparison of model data (Deutscher Wetterdienst) and measured data at the Arkona MARNET station. 

Sea state forecasts from the DWD have been available since 1991. The WAM model has been used since 2000 on a 11 km raster. It is driven by the wind at a height of 10 m from the meteorological local model (7 km) and calculates forecasts up to 3 days in advance. Model quality can be obtained from Fig. 7.14. Wave heights from the first 12 h of successive forecast calculations are compared with measurements from the Arkona MARNET station. Although the average difference between the model and measuring value (bias) is small, the model overestimates high sea state by approximately 10% at this position... 

Longer series of measurements of the sea state in the Baltic Sea are available only for a few stations (see Section 7.1.2). For the Arkona MARNET station, a 4-year series of measurements has been analyzed and prepared to the following wind and sea state statistics ... 

TABLE 7.12 Wind and Sea State Statistics for the Arkona MARNET Station (January-... 

In the western Baltic Sea, the cyclone reached its maximum wind force in the evening of January 8, 2005, when the center of the depression was located over Sweden. The wind direction (WSW) was parallel to a line between the Lubeck Bay and the Arkona MARNET Station, that is, in an optimum direction for a fetch of maximum length in this sea area. Wind and sea state measurements are available from the Darss SiU and ArkonaBasin stations (see also Fig. 7.25). Wind speed measured at a height of 10 m was approximately identical at both stations and was about 20 m/s (39 kn) for almost 24 h. The maximum value was approx. 24 m/s (47 kn) and remained at this level at Arkona for 6 h with only slight changes in wind direction. 

For comparison, the wave parameters calculated with the routine forecast model of the DWD and the measurements at Arkona MARNET station are shown together in... 

FIGURE 7.25 Wind and wave conditions during cyclone Gudrun/Erwin Measurements (solid line) Model data (dashed line) (a) Darss Sill Station (54°42 N, 12 42 E) (b) Arkona MARNET Station (54°53 N. 13°52 E). 

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