MONITORING OF TRANSPORTS OF THE OCEAN CURRENT USING BY INVERTED ECHOSOUNDERS

摘要

Current velocity can be determined by measuring the difference of reciprocal sound wave traveling times between two points, which is well known as time difference method. We developed inverted echo sounder in order to apply this method to monitoring of transports of the ocean current. Measurement of mean current velocity can be made with difference of reciprocal travel times of sound wave along two sides of a triangle in a vertical plane, which is constructed by a base side between two inverted echosounders moored about 10 km apart on the sea bottom and two sides of a traveling path of a sound wave reflected by the sea surface from one inverted echosounder to other. At the same time, depth-integrated heat contents can be obtained by using vertical round trip time of sound wave emitted from each inverted echosounder. In 1996, six sets of inverted echosounders were deployed over the Izu Ridge at the depth of about 1100 m, where the Kuroshio flows eastward. In this paper, we present how to estimate transport of the ocean current from acoustical observation data.