On the Mechanism of Cyclonic Circulation in Lake Kinneret in Summer

Abstract

In summer, the circulation of water in Lake Kinneret stratified in the vertical direction is characterized by the presence of a quasistationary jet coastal cyclonic current [S. Serruya, Ver. Int. Verein. Limnol., 19, 73 (1975) and S. Serruya (ed.), Lake Kinneret, Junk, Hague (1978)]. This circulation cannot be described by a fairly complete three-dimensional baroclinic model [V. A. Ivanov, S. P. Lyubartseva, et al., Morsk. Gidrofiz. Zh., No. 6, 26 (2001)] if the motion is induced by the action of monthly average external factors. Within the framework of a two-layer model of round lake with parabolic bottom, it was shown [H. W. Ou and J. R. Bennett, J. Phys. Oceanogr., No. 6, 1112 (1979)] that cyclonic currents may appear under the action of daily variations of spatially homogeneous winds caused by the influence of nonlinearity and friction on the forced Kelvin internal waves. Daily variations of the wind in the investigated region are connected with the consecutive transformations of the local land breeze (i.e., a relatively weak wind blowing from the land to the lake and characterized by the presence of wind convergence) into the large-scale sea breeze (i.e., a practically uniform strong wind blowing from the Mediterranean Sea) and vice versa. However, the numerical experiments performed by using the three-dimensional model of Lake Kinneret [V. A. Ivanov, S. P. Lyubartseva, et al., Morsk. Gidrofiz. Zh., No. 6, 26 (2001)] show that, for the correct description of the circulation of waters in the lake, it is necessary to take into account not only the time variability of the wind [see H. W. Ou and J. R. Bennett, J. Phys. Oceanogr., No. 6, 1112 (1979)] but also its horizontal inhomogeneity, i.e., the cyclonic vorticity of the wind, predominant in its daily variation. The indicated cyclonic vorticity is formed during the period of land breeze as a result of the wind convergence caused by the rotation of the Earth.