Turnover times for the water above sill level in Gullmar Fjord

Daily hydrographic measurements between 1954 and 1986, monthly environmental monitoring data from the last decades, and high-resolution data from 2001 are combined to obtain statistics on the exchange of the water above sill level in Gullmar Fjord, Sweden. The analyses show: (i) that the average turnover time is 16–26 days for the water above the halocline (S<28), and 40 days for the intermediate water below the halocline, (ii) that the exchange is dominated by baroclinic currents caused by vertical fluctuations of the halocline outside the fjord, and (iii) that the statistics for the turnover times are relatively independent of year and season. One implication of these results is that a coupling between climate variations and water quality in Gullmar Fjord, cannot be explained in terms of variations in the water exchange.