Acoustic Sounders
Inverted Echo Sounders (IES) measure the temperature of the water column at a single point. The IES is attached to the ocean bottom. It emits a sound pulse aimed toward the surface of the ocean. The sound pulse will reflect off the surface of the ocean and return to the bottom. The IES listens for the return of the sound pulse from the ocean surface. The travel time of the sound is used to calculate the speed of sound through the water. The temperature profile is calculated from the speed of sound through the water. The IES must be calibrated with a measurement of the water column properties. Sometimes a pressure sensor is used with the IES to make the calibration. Additional information available at "http://omp.gso.uri.edu/dosits/people/resrchxp/1.htm" [Summary provided by University of Rhode Island]
IES