An instrument that measures the velocity and direction of water fl.ow in estuaries is described. The magnitude is obtained by measuring the phase lag or advance, caused by motion of the water, in an ultrasonic wave. The instrument can be towed or suspended from a vessel or operated unattended at a remote station for a week.
Middleton, Foster H.. 1955. "An ultrasonic current meter for estuarine research." Journal of Marine Research 14, (2). https://elischolar.library.yale.edu/journal_of_marine_research/828