Large Amplitude Nonlinear Internal Surge in Lake Biwa

Abstract

An international program, the Biwako Transportation Experiment (BITEX'93), was executed in the summer of 1993. A current meter chain and a thermistor chain were then moored in the BITEX area. This permitted observations of the vertical dynamic and thermal structure of long internal waves and preceding internal fronts. After a strong typhoon, a marked depression of the thermocline appeared with an amplitude of 40 m which reached the lake bottom and induced a hypolimnion jet couple with a maximum velocity greater than 60 cm⋅sec^-1. The correspondence between current speed and turbidity in the hypolimnion shows the possibility that sediment resuspension was generated by the event. Analyses indicated that this kind of V-shaped surge is due to the nonlinear long wave effect.