Zonal (Earth sciences)
(Redirected from Zonal)
In geography, geophysics, and meteorology, zonal usually means "along a latitude circle", i.e. "in the east-west direction".
In atmospheric sciences the zonal coordinate is denoted by x, and the zonal wind speed by u.
By analogy, the term "zonal flow" has been adopted in magnetic confinement fusion to describe a mean plasma flow within a magnetic surface primarily in the poloidal direction (i.e. the short way around the torus), the corresponding coordinate being denoted by y in the slab approximation or θ in magnetic coordinates. Zonal flows in this context are further characterized by (a) having little or no variation in the toroidal direction (the long way round the torus) -- they are n = 0 modes, (b) having significant variation in magnitude and sign in the direction transverse to the magnetic surfaces (to distinguish them from global plasma rotation), and (c) having zero natural frequency (i.e. apart from any acquired from nonlinear interactions).
- See also: Meridional
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Climatology | Geology