Response to comment by Dr. A.S. Kowalski on “The storage term in eddy flux calculations”

Kowalski correctly points out that the analysis in [Finnigan, J.J., 2006. The storage term in eddy flux calculations. Agric. Forest Meteorol., 136, 108–113] ignores the interplay between the storage terms and the WPL corrections. In this note we develop an expression for the vertical convective velocity that accounts for the effect of both the ‘steady state’ and unsteady ‘storage’ WPL terms on the flux of a trace gas like CO2 measured with an open path sensor and sonic anemometer. The expression is derived using the mass density rather than the mixing ratio so that the eddy fluxes take the conventional covariance form that is commonly used in turbulence textbooks.