engleski

Various physical processes documented by the Bakar sea-level data

Tide gauge at Bakar has been installed in 1929 and, with a break during the Second World War, has been working ever since. After Trieste, it is second longest operating tide-gauge station in the Adriatic and the records are among longest and most complete in the Mediterranean area. These sea level data have been employed by a number of authors to study different physical processes - from time scales of several minutes, corresponding to free oscillations (seiches) of Bakar Bay, through day to several weeks variability caused by tidal, wind and air pressure forcing, and seasonal variability due to exchange of heat and water between atmosphere and sea, to interannual and still longer, interdecadal variability of mean sea level height resulting from a combined effect of global sea-level rise, regional effects and local tectonic movements. In this paper, a several day record of sea level is chosen in order to illustrate the most prominent of these processes. Thus one can follow the action of tides, sea-level variations in respect to synoptic weather charts, and as the cyclone passes, the generation and decay of Bakar Bay seiches, which are triggered off by abrupt meteorological change. Since time record is a result of various processes which take place at different time scales, they are distinguished in frequency domain by performing spectral analysis; energy peaks at certain (bands of) frequencies are connected to the processes discussed. Each of the processes, depending on the forces which are at work, is governed by different physics, and can in a simplified way be described by a theoretical model. As an illustration, results of a two-dimensional model describing seiches of Bakar Bay are given.

sea level; tides; seiches; atmospheric forcing; Bakar

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