This paper describes a new low-cost method of measuring coastal surface currents with markers dropped from a light aircraft at each of a series of stations. Each marker consists of a cloth bag containing floats and a different dye. One marker, with anchor attached, remains stationary while a second marker, with drogue attached, moves with the current. The specific dye with each marker disperses slowly and contjnuously through the cloth into the water and aids in the subsequent location of each marker....
Welsh, J. G.. 1967. "A new method of measuring coastal surface currents with markers and dyes dropped from an aircraft." Journal of Marine Research 25, (2). https://elischolar.library.yale.edu/journal_of_marine_research/1097