Friction velocity estimation from the Reynold stress tensor

The friction velocity is computed from sonic anemometer data without the need to correct tilt angle errors

Friction velocity calculation with Klipp's method (2018)

The friction velocity is computed using a Matlab implementation of the method proposed by Klipp [1]. This method has the advantage to avoid the correction of instrument tilt by using the Reynolds stress tensor invariants. In [1], the friction velocity calculated for neutral conditions is found to be in good agreement with the standard method. Larger discrepancies are expected for non-neutral conditions or low wind speeds but produce a dimensionless shear that scales well with the non-dimensional Obukhov length. Type of application: Micrometeorology, surface layer turbulence.

Content

The present Matlab submission contains:

• A function "frictionVelocity.m", which computes the friction velocity using the standard method or the one proposed in [1]. The latter method is more appropriate in complex terrain and a neutral atmosphere.
• An example file "Example1.mlx" that compares the 2 methods
• A data file "data.mat" that contains simulated wind turbulent velocity records

Reference

[1] Klipp, C. (2018). Turbulent friction velocity calculated from the Reynolds stress tensor. Journal of the Atmospheric Sciences, (2018).