File:Collected reprints - Atlantic Oceanographic and Meteorological Laboratories (and) Pacific Oceanographic Laboratories (1968) (20656260812).jpg

Title: Collected reprints / Atlantic Oceanographic and Meteorological Laboratories (and) Pacific Oceanographic Laboratories
Identifier: collectedreprin00atla (find matches)
Year: 1968 (1960s)
Authors: Atlantic Oceanographic and Meteorological Laboratories; Pacific Oceanographic Laboratories; United States. Environmental Science Services Administration. Research Laboratories; Environmental Research Laboratories (U. S. )
Subjects: Oceanography Periodicals.
Publisher: Washington, D. C. : U. S. Dept. of Commerce, Environmental Science Services Administration, Research Laboratories : For sale by Supt. of Docs. U. S. G. P. O.
Contributing Library: Penn State University
Digitizing Sponsor: LYRASIS Members and Sloan Foundation

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Vastly more elegant that Lt. Boon's cookie cutter is the C&GS's "ODESSA" system used by LASIL in a study of the interaction between tidal currents, underwater sand waves, and the transport of fluorescent sand grains. The study was conducted in a tidal inlet between the islands of North and South Bimini in the Bahamas. "ODESSA" is a complete sys- tem of telemetering oceanographic sensors and with it LASIL monitored the inlet currents at 16 points. In deploying the "ODESSA" system, it was first neces- sary to mount the sensor packages rigidly on tripods at the Lerner Marine Laboratory on North Bimini. These tripods were taken one by one on a workboat to the proper points in the inlet, where they were emplaced during slack water. Electrical cables from the sensors were then connected to re- cording units on shore. Once running, the "ODESSA" faith- fully kept track of the speed and direction of the currents as water rushed in and out of the inlet. TTie most exciting part of the inlet study involved keep- ing track of the movement of sand waves on the floor of the inlet. For this, it would be necessary for the LASIL workers to become "menfish." Donning SCUBA or HOOKAH gear, the oceanographers first placed a rigid, 200-foot "ruler" on the bottom, oriented perpendicular to the crests of the sand waves and made perfectly level. Then, as the current waxed and waned, flooded and ebbed, LASIL menfish made re- peated runs back and forth along the ruler with underwater movie cameras. TTiere, 20 feet down in the crystal clear Bahamian water, they trapped the motion of foot-high dunes and pearly-while sand as the sea floor undulated rhythmically along in the direction of the currents. LASIL staged something of an underwater ballet in order to freeze the movement of individual sand grains which — by their skipping over the backs, crests, and steep fronts of the dunes — cause the downcurrent motion of the dune forms. Choreography for the sampling runs involved a lead player who cut open tubes of fluorescent sand laid out on the bottom parallel to one of the dune crests. At precisely timed intervals, this leader would signal three other SCUBA-dancers holding paint rollers. TTiese diver-dancers would press the roller on the bottom and glide off over a prescribed down- current course, unrolling a plastic film covered with silicone grease. At the end of the 60-foot-long "stage," the film was expended and the divers would kick to the surface. Another diver would then flutter to the stage and coax the plastic film up off the bottom. In a skiff on the surface, a "stagehand" would reel the film out of view of the audience of lobsters, grouper, and an occasional barracuda. Study of the brilliantly fluorescent grains on the LASIL tapes is permitting testing of a backlog of theoretical and laboratory work on sediment transport by currents. Thus, LASIL's research program carries forward a vital environ- mental approach to understanding the various interactions along the boundary where the sea meets the land. ^ (Right I Hurricane Faith waves attacking the shore of Cape Cod. Photo was taken on Sept. 2. 1966 at Truro. Mass., from seaside cliffs 130 ft. in elevation. The waves shown have deformed to multiple crests in passing over the off-shore bar. The waves in the fore- ground, about to break, are about seven feet in height. (Below) LASIL staff members set an ODESSA sensor in place at Bimini, B.W.I.
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