A generalized planar fit method for sonic anemometer tilt correction

Abstract

The Army Research Laboratory (ARL) deployed an array of sonic anemometers mounted on five towers in Oklahoma City, Oklahoma, during the Joint Urban 2003 field campaign, a cooperative undertaking to study turbulent transport and dispersion in the atmospheric boundary layer within an urban environment. The sonic anemometer data must be tilt corrected in order to obtain the most accurate analyses of turbulent variances and covariances.

Several methods have previously been proposed for tilt correction of sonic anemometer data. Most of these methods were devised for use only in the case of homogeneous level terrain without nearby obstructions. We have modified the planar fit method of Wilczak, Oncley, and Stage (2001) for use where the anemometers are deployed in the non-homogeneous terrain common to a variety of real environments such as urban locations or forest canopies. This generalized tilt correction method preserves real variations in mean vertical wind due to local obstructions such as nearby buildings. This tilt correction method will be described, and sample turbulent statistics from the application of this method to Joint Urban 2003 data will be shown.