密度流におけるコリオリ効果に関する研究

Abstract

To parameterize Coriolis effect on density current, governing equations are nondimensionalizedby selecting the velocity and the buoyancy scales which are usual in the non-rotating system.Among the dimensionless parameters, Ro=A1/3L-4/3f-1 and Ev=νvf-1H2 are considered to bemost important in a natural basin, where A is the total buoyancy flux into the basin, L width ofthe basin, f Coriolis parameter, νv vertical eddy viscosity coefficient, H water depth. The de-pendence of phenomenon on these two parameters is exermined experimentally and numericallyunder a simplified condition.Longitudinal convection is deflected from the basic one without rotation as Rv decreases, andthe direction of convection and that of equi-picnal lines crosses with a small angle prescribed by asmall value of Ev. By the effect of rotation, the longitudinal dispersion of buoyancy is weakened, resulting in a horizontal large gradient of buoyancy.The density current in southern part of Lake Biwa was also simulated. The Coriolis effect on itis found to be a restricting factor for that current.