On the resonance-wave mechanism of major Baltic inflows

Abstract

The features of the spatiotemporal variability of the sea level in the North and Baltic seas during the periods of formation of major Baltic inflows are investigated using the analysis of satellite altimetry data. It is demonstrated that dramatic drops in the sea level between the Baltic and North seas are observed during a few weeks before major inflows. A process of intensive inflows of the North Sea water to the Baltic Sea is accompanied not only by horizontal motions but also by vertical ones manifested in the increase in convergent flows in the North Sea and divergent flows in the Baltic Sea. A pronounced feature of the low-frequency dynamics of water of the North and Baltic seas is its wave structure. In both seas, low-frequency waves with the periods of 14–36 days propagate with the eastern component of the phase velocity along the isobaths and are identified as barotropic topographic Rossby waves. Phase velocities and lengths of low-frequency waves in the Baltic Sea are smaller by several times than those in the North Sea. Using the data of the analysis of meteorological information, a resonance-wave mechanism of generation of major Baltic inflows is studied.