Flux-ratio method

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flux-ratio method

A procedure originally proposed by Ball in 1960 to estimate the entrainment velocity we into the top of the convective boundary layer by requiring a fixed value for the ratio A of entrained heat flux to surface heat flux (
ams2001glos-Fex03
in kinematic form):
ams2001glos-Fe7
where Δθ is the potential temperature change across the stable layer at the top of the mixed layer.

The flux ratio, sometimes called the Ball ratio, is empirically estimated to be A = 0.2 ± 0.05. This method works quite well for pure free convection but is inadequate when a significant portion of turbulence is generated by wind shear.
See eddy correlation.

Ball, F. K. 1960. Control of inversion height by surface heating. Quart. J. Roy. Meteor. Soc.. 86. 483–494.

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