Ocean convergence and the dispersion of flotsam.

Autor:	D'Asaro EA; School of Oceanography, College of the Environment, University of Washington, Seattle, WA 98105; dasaro@apl.washington.edu.; Applied Physics Laboratory, University of Washington, Seattle, WA 98105., Shcherbina AY; Applied Physics Laboratory, University of Washington, Seattle, WA 98105., Klymak JM; School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, Canada, V8W 3P6.; Department of Physics and Astronomy, University of Victoria, Victoria, BC, Canada, V8W 3P6., Molemaker J; Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095., Novelli G; Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, FL 33149., Guigand CM; Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, FL 33149., Haza AC; Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, FL 33149., Haus BK; Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, FL 33149., Ryan EH; Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, FL 33149., Jacobs GA; Naval Research Laboratory, Stennis Space Center, MS 39529., Huntley HS; School of Marine Science and Policy, College of Earth, Ocean and Environment, University of Delaware, Newark, DE 19716., Laxague NJM; Lamont-Doherty Earth Observatory, Earth Institute, Columbia University, Palisades, NY 10964., Chen S; Department of Atmospheric Sciences, College of the Environment, University of Washington, Seattle, WA 98195., Judt F; Mesoscale and Microscale Meteorology Laboratory, National Center for Atmospheric Research, Boulder, CO 80307., McWilliams JC; Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095., Barkan R; Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095., Kirwan AD Jr; School of Marine Science and Policy, College of Earth, Ocean and Environment, University of Delaware, Newark, DE 19716., Poje AC; Department of Mathematics, College of Staten Island, Staten Island, NY 10314., Özgökmen TM; Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, FL 33149.
Jazyk:	angličtina
Zdroj:	Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2018 Feb 06; Vol. 115 (6), pp. 1162-1167. Date of Electronic Publication: 2018 Jan 16.
DOI:	10.1073/pnas.1718453115
Abstrakt:	Floating oil, plastics, and marine organisms are continually redistributed by ocean surface currents. Prediction of their resulting distribution on the surface is a fundamental, long-standing, and practically important problem. The dominant paradigm is dispersion within the dynamical context of a nondivergent flow: objects initially close together will on average spread apart but the area of surface patches of material does not change. Although this paradigm is likely valid at mesoscales, larger than 100 km in horizontal scale, recent theoretical studies of submesoscales (less than ∼10 km) predict strong surface convergences and downwelling associated with horizontal density fronts and cyclonic vortices. Here we show that such structures can dramatically concentrate floating material. More than half of an array of ∼200 surface drifters covering ∼20 × 20 km 2 converged into a 60 × 60 m region within a week, a factor of more than 10 5 decrease in area, before slowly dispersing. As predicted, the convergence occurred at density fronts and with cyclonic vorticity. A zipperlike structure may play an important role. Cyclonic vorticity and vertical velocity reached 0.001 s -1 and 0.01 ms -1 , respectively, which is much larger than usually inferred. This suggests a paradigm in which nearby objects form submesoscale clusters, and these clusters then spread apart. Together, these effects set both the overall extent and the finescale texture of a patch of floating material. Material concentrated at submesoscale convergences can create unique communities of organisms, amplify impacts of toxic material, and create opportunities to more efficiently recover such material. Competing Interests: Conflict of interest statement: E.A.D. and T.F. are coauthors on a 2014 paper. This was a brief announcement that did not involve any scientific collaboration. (Copyright © 2018 the Author(s). Published by PNAS.)
Databáze:	MEDLINE
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