On the Ekman Spiral with an Anisotropic Eddy Viscosity
2010
Wirth, A
The eddy viscosity is a fourth-order tensor in three-dimensional space. When considering the viscous effects on the horizontal velocities in the vertical direction it is reduced to a second-order tensor in two-dimensional space, and is not necessarily horizontally isotropic. Anisotropic coherent structures (rolls) are a conspicuous feature of the planetary boundary layer. There is no reason to suppose that they should give rise to a horizontally isotropic eddy viscosity. The effects of an anisotropic constant eddy viscosity tensor on the Ekman layer dynamics is determined analytically. The shape of the Ekman spiral is modified. The magnitude of the bottom shear and the Ekman transport is changed in magnitude and rotated within an angle of 90°.
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