16 
raphic structure of the German Bight. Due to the con- 
stant - more or less strong - influx of heavy North 
Sea water from westerly and northwesterly directions 
and due to the seasonally changing influx of the run- 
off, a mixing zone between these two water masses is 
formed. 
Within the mixing zone a boundary layer is built up 
which, ideally, is inclined from west to east, from the 
surface to the bottom. Goedecke has named this frontal 
zone "German Bight convergence". There is an inter- 
relation between the position and the intensity of the 
convergence and the residual current system, The zone 
of convergence may essentially influence the spreading 
and mixing of nutrient, pollutant and noxious sub- 
stances that are transported by the rivers into the 
German Bight. 
Dietrich (1951), Tomczak and Goedecke (1962, 1964, 1967) 
have described the seasonal changes of the hydrographic 
parameters in the form of mean value atlases using 
observations from the period 1902 - 1954. As to the 
long-term variations of the hydrographic parameters 
the German Bight, a report has been given by Becker 
and Kohnke (1978). 
in 
In contrast to the numerous published hydrographic inves- 
tigations from this area only very few publications 
on the periodic and aperiodic dynamic processes in this 
area are available. Neumann and Meier (1964) have pub- 
lished tidal stream charts. Mandelbaum (1934) has de- 
termined residual currents from the long-term current 
cross observations from the light vessels "Borkumriff" 
and "Amrumbank". Accordingly, residual surface currents 
of about 5 cm. sg 71 can be expected parallel to the coast. 
Koltermann and Lange (1977) showed that the residual