Fluxes of chemically reactive species inferred from mean concentration measurements

A method is presented for the calculation of the fluxes of chemically reactive species on the basis of routine measurements of meteorological variables and chemical species. The method takes explicitly into account the influence of chemical reactions on the fluxes of the species. As a demonstration of the applicability of the method, micro-meteorological and atmospheric chemistry measurements (O3, NO and NO2) collected at Zegveld (NL) in 1994 are used to calculate the fluxes of chemically reactive species. In the absence of direct flux measurements, the calculated fluxes are compared to the fluxes obtained without taking the chemical effect into account. At 2 m from the surface the effect of chemical transformation is less than 10% whereas at 10 m it can be as much as 40%. An explanation of this effect is given in terms of the ratio of the gradients of the species and the ratio of the time scale of turbulence to that of chemistry. The method presented is applicable to any surface-layer stability or chemical system.