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 meteorologica l variables and chemical species. The method takes explicity into acco unt the influence of chemical reactions on the fluxes of the species. As a demonstration of the applicability of the method, micro-meteorolo gical and atmospheric chemistry measurements (O-3 NO and NO2) collecte d at Zegveld (NL) in 1994 are used to calculate the fluxes of chemical ly reactive species. In the absence of direct flux measurements, the c alculated fluxes are compared to the fluxes obtained without taking th e 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 r atio of the gradients of the species and the ratio of the time scale o f turbulence to that of chemistry. The method presented is applicable to any surface-layer stability or chemical system. (C) 1997 Elsevier S cience Ltd.