Diagnostic Analysis of Water Circulations in Lake Biwa
Shuichi ENDOH
Journal of the Oceanographical Society of Japan, Vol, 34, pp. 250 to 260, 1978
@A diagnostic model is developed for the study of steady water circulations during summer in Lake Biwa. The most characteristic feature of the present model is to include the vertical friction terms in the basic equations, so that it is not necessary to assume a level of no-motion. Under no-wind condition, the velocity field is calculated from the density field obtained by successive observations of water temperature using a bathythermograph. The comparisons of the present calculation with a dynamical calculation and direct current measurements indicate that the present model surpasses a dynamical calculation in the respects that 1) vertical circulation can be estimated and 2) the flow pattern in the deep layers can be obtained more reliably. One of important results of the present calculation is that a large vertical circulation has been found accompanied by the large counterclockwise gyre in the north basin. Preliminary results of direct current measurements by cross-board drogues also seem to suggest the existence of the circulation.

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