The essence of the Webb, Pearman and Leuning (WPL) correction: w-  correction

Vertical wind velocity (w) and gas density (c) are two key variables for estimating trace gas fluxes using the eddy covariance (EC) technique. For many decades within the EC community, the Webb, Pearman and Leuning (WPL) theory proposed by Webb et al. (1980) has been widely accepted as a “density effect correction” for flux calculations. However, we found that Webb et al. (1980) derived their equations correctly by calculating the unmeasurable mean vertical velocity (