INTERCOMPARISON OF TROPOSPHERIC OH RADICAL MEASUREMENTS BY MULTIPLE FOLDED LONG-PATH LASER-ABSORPTION AND LASER-INDUCED FLUORESCENCE

An intercomparison of in-situ OH measurements by differential optical absorption spectroscopy (DOAS) and laser-induced fluorescence spectros copy (LIF) was carried out in August 1994 in a clean rural environment in North-East Germany. A large data set of temporally overlapping OH measurements with well defined measurement errors was obtained and com pared. Both instruments encountered the same air masses, except when t he wind came from NNW and caused a perturbation of the DOAS measuremen ts. Excluding that wind sector, the weighted regression analysis of 13 7 data pairs (70% of all available data pairs) yields a linear relatio nship between the BOAS and LIF measurements with a correlation coeffic ient r=0.90. The unity slope (1.01+/-0.04) and the non-significant int ercept (0.28+/-0.15)x10(6) cm(-3) demonstrate that both OH instruments agreed excellently in their calibrations and accurately measured OH.