水温計格子を用いた浅水湖の成層破壊過程の観測

Abstract

Temperature fluctuations due to interfacial waves were measured in a shllow lake using the thermistor grids. The waves as roughness on the deformable density interface were observed between the basic internal wave of the maximum buoyant frequency and the surface wind ripples.On the transition from smooth to rough interface, where frequency spectrum shows an inertial subrange, beyond which the viscous-convective subrange is seen as mixing goes on.The waves are generated from amplified internal wave, and wind waves copy themselves on the interface through the resonance with much slower interfacial ones.Diffusivity takes the peak at the bottom of thermocline, and for such a diffusivity profile, the log+linear law for temperature was deduced.Assuming the system is non-rotating, a profile model considering the wave steepness is shown, which estimates the flux as well as the diffusivity, and the former was compared well with the measured flux.Superimposing the first few modes of the cellular motion, the fluctuation of buoyancy in vertical was found similar with the measured one.