Physics:Okubo–Weiss parameter
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In fluid mechanics, the Okubo–Weiss (OW) parameter, (normally given by "W") is a scalar quantity used to partition a flow field into regions dominated by rotation (vorticity) and regions dominated by deformation (strain). It is widely applied in geophysical fluid dynamics, particularly in the analysis of oceanic and atmospheric flows, where it serves as a diagnostic tool for identifying and characterizing coherent structures such as eddies.[1]
For a horizontally non-divergent flow in the ocean, the parameter is given by:[1]
where:
- is the normal strain.
- is the shear strain.
- is the relative vorticity.
OW is widely used in the fields of Meteorology and Oceanography to identify regions of strong vorticity within atmospheric and oceanic flows. It is often employed as a tracer for cyclonic development because it is generally less "noisy" than relative vorticity alone. The Okubo-Weiss parameter quantifies the balance between rotational and deformational components of the flow: positive values indicate that deformation dominated, while negative values indicate that rotation is dominant.
References
- ↑ 1.0 1.1 Isern-Fontanet, Jordi; Font, Jordi; García-Ladona, Emilio; Emelianov, Mikhail; Millot, Claude; Taupier-Letage, Isabelle (2004). "Spatial structure of anticyclonic eddies in the Algerian basin (Mediterranean Sea) analyzed using the Okubo–Weiss parameter". Deep Sea Research Part II: Topical Studies in Oceanography (Elsevier) 51 (25–26): 3009–3028. doi:10.1016/j.dsr2.2004.09.013.
External Links
- Okubo, Akira (1970). "Horizontal dispersion of floatable particles in the vicinity of velocity singularities such as convergences". Deep-Sea Research and Oceanographic Abstracts (Elsevier) 17 (3): 445–454. doi:10.1016/0011-7471(70)90059-8.
- Weiss, John (1991). "The dynamics of enstrophy transfer in two-dimensional hydrodynamics". Physica D: Nonlinear Phenomena (Elsevier) 48 (2–3): 273–294. doi:10.1016/0167-2789(91)90088-Q.
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