Structure function

From Glossary of Meteorology
(Redirected from Structure constant)

structure function

The variance of the difference of a turbulence quantity in space or time, given by
where q is a scalar or a velocity component.

For small separations (rz, where z is the height above the surface), this equation may be written
where b is about 0.7 for temperature and 0.76 for humidity, χq is the rate of destruction of q2/2 by molecular diffusion, and ε is the rate of dissipation of turbulence energy into heat. The coefficient
is called the structure constant of q. This formulation eliminates the mean component of a fluctuating quantity and provides a measure of fluctuation variance within a band of wavelengths (or frequencies) determined by the separation distance (or lag time).

Panofsky, H. A., and J. A. Dutton 1984. Atmospheric Turbulence. Wiley, . 182–183.

Copyright 2022 American Meteorological Society (AMS). For permission to reuse any portion of this work, please contact Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act (17 U.S. Code § 107) or that satisfies the conditions specified in Section 108 of the U.S.Copyright Act (17 USC § 108) does not require AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a website or in a searchable database, or other uses of this material, except as exempted by the above statement, require written permission or a license from AMS. Additional details are provided in the AMS Copyright Policy statement.