(C201) <<< Previous | Back to Abstracts Page | Next >>> (C203)
Oil dispersion in the ocean
J.M. Redondo, R. Castilla, J. Grau and A. Platonov
Dept. Fisica Aplicada, Univ. Politecnica de Catalunya
redondo@fa.upc.edu(Abstract received 05/09/2005 for session B)
ABSTRACT
In recent years the marine pollution has been highlighted thanks to the advances in detection techniques. There is also more public awareness to both the large nautical catastrophes (e.g. oil tankers Amoco Cadiz, Exxon Valdez and recently Erika and Prestige) and the habitual smaller oil spills from the ships. The range of marine pollution events, should even the very smaller oily spills of a few square meters caused by small boats. The middle size oil spills often originate due to coastal sources and from small accidents or habitual cleaning of ballast water in ships. The great oil spills are caused by crude/oil tankers’ catastrophic accidents of varied consequences. From the analysis of SAR observations and new satellite based sensors new methods of oil spill detection in the Ocean, coupled with self-similar statistical techniques allows to determine with precision the range of event and its topological structure. We analyzed more than 700 SAR images obtained during 1996-1998 and compared the small pollution events with the historical databases of great marine accidents during 1966-2004 in European coastal waters. The interactions between the self-similar ocean turbulent, where the Rossby deformation Radius plays an important role and the oil spills is used to model numerically the dispersion. Traditionally in environmental studies of diffusion, oil patches have been numerically predicted and computed with homogeneopus environmental forcing and random free paths, which gives Brownian behavior. These stochastics methods have the objection that don't take into account the topòlogy of flow profile. On the other hand, there are many ways to simulate a fluid flow, but when this is turbulent, these simulations become complicated, expensive and inaccurate. Our aim is to present the theoretical and experimental bases needed to simulate acurately the behaviour of oil spills (or tracer particles) in a turbulent flow, in a simple and efficient way that may be updated in an emergency with the latest output from dedicated environmental Atmosphere (wind) and ocean currents and wave nested models. This is acomplished with a kinematic simulation model and in the presentation we validate the results with detected oil spills. We use a 2D Kinematic Simulation (KS) model, suggested by Kraichnan (1966,1970) and developed by Fung et al.(1990. In this model, velocity field is generated, mantaining the Energy and enstrophy cascades through a Fourier series of random modes. The typical scales and the energy and enstrophy spectral power laws of the turbulence are inputs of the model. As we do not solve the flow in a discrete grid, but use a random predictive expression, we can simulate the flow (with updated wind, wave and current data) at a wide range of scales. The filamentation and multifractal characteristics of both model and observations are compared and discussed.
(C201) <<< Previous | Back to Abstracts Page | Next >>> (C203)
2005 LAPCOD Meeting, Lerici, Italy, June 13-17, 2005