Lc. Lundhansen et al., MODES OF STRATIFICATION IN A SEMIENCLOSED BAY AT THE NORTH SEA-BALTICSEA TRANSITION, Estuarine, coastal and shelf science, 42(1), 1996, pp. 45-54
Conductivity, temperature and depth (CTD) measurements were recorded w
eekly at a fixed position in the shallow water of Arhus Bay over a per
iod of 1 year. Variations in stratification and salinity are described
in this study. Outflow of low salinity water from the Baltic Sea, and
an estuarine return flow of high salinity bottom waters originating i
n the North Sea were observed. Strong stratification occurs during spr
ing, summer and late autumn, whereas stratification is weak or absent
during winter. A stratification model in terms of the potential energy
of the water column (phi) has been applied including wind, solar inso
lation, estuarine circulation and current terms. Observations of strat
ification are very well described by this model, although considerable
differences were found to occur during a period of very strong strati
fication. The interface is placed at a water depth of about 8 m during
spring and early summer, and at a depth of about 12 m during autumn.
A comparison of frequently used stratification parameters shows a high
ly positive correlation between phi and the density difference between
surface and bottom water. A positive correlation between phi and Brun
t-Vaisala frequency was also found in periods of stable oceanographic
and meteorological conditions, whereas no correlation was found in per
iods of unstable conditions. (C) 1996 Academic Press Limited