Variable eddy viscosities in the atmospheric boundary layer from ageostrophic wind-speed profiles

TL;DR

This paper develops explicit height-dependent eddy viscosity profiles in the atmospheric boundary layer using convex wind speed profiles, enabling better inference of Ekman layer thickness across various deflection angles.

Contribution

It introduces a novel parameterization of eddy viscosity based on wind profiles and deflection angles, extending Ekman layer analysis beyond classical assumptions.

Findings

Derived explicit eddy viscosity profiles from wind data

Linked deflection angles to Ekman layer thickness

Provided a framework for analyzing momentum transfer in the boundary layer

Abstract

We generate explicit height-dependent eddy viscosity coefficients in the Ekman layer from convex wind speed profiles. The solutions we obtain are parameterized in terms of the relative deflection angle between the wind directions at the top and bottom of the flow, as well as the geostrophic wind speed and a velocity scale we interpret as the transfer rate of horizontal momentum in the vertical direction. The solutions may be used to infer the thickness of the Ekman layer for a variety of deflection angles different from deflection angle of the classic Ekman spiral.