STUDY OF SEICHE IN LAKE BIWA-KO (III) : SOME RESULTS OF A NUMERICAL EXPERIMENTS BY NONLINEAR TWO-DIMENSIONAL MODEL

Abstract

The possible periods of the seiche in Lake Biwa-ko are given as 255.5, 79.8, 69.1, 51.1, 38.7, 31.9 minutes and so on from the numerical experiments by nonlinear two-dimensional model described in a former paper of the same title (Imasato [1971]). In this paper, some characteristics of the seiches with the period 51.1, 38.7 and 31.9 minutes are discussed. It is found that the seiche with the period 31.9 minutes consists of the four different component oscillations. These periods from the numerical experiments agree well with the observed periods. The amplitude variations of each seiche with the wind direction are discussed, too. From a numerical experiment by using the model with a distribution of wind direction, it is found that the st"iche with the period 255.5 minutes is controled by the wind field over the south basin, the seiches with the period 69.1, 51.1 and 31.9 minutes by the wind field over the north basin, and the seiches with the period 79.8 and 38.7 minutes by the wind field over both basins.