小川原湖に発生する傾斜プルームの音響探査観測

抄録

An inclined plume, generated by saline water, is visualized with an echo sounder. The output signal is stored as digital data so that the picture of reflection distribution can be reproduced with any intensity scale and size by post-processing. The pictures are compared with the data of salinity and temperature profiles obtained from STD measurement. The location of horizontal streaks in the picture of echo image corresponds to the depth of density jumps although the intensity of streaks does not correspond to the intensity of density jumps. The densimetric interface of the inclined plume can be identified as the lowest streak along the bottom.
Richardson number of the plume(Ri) is estimated from the amplitude of stationary wave on the undulations of the bed topography based on an assumption of the local conservation of specific energy. The estimated Ri and the entrainment coefficient(E) calculated from the data of STD measurement show that E decreases rapidly when Ri approaches to 1.0. This fact means that the frequently used relationship of power law does not hold well.