We analysed the
coupling of atmospheric particle formation and sulphuric acid during the
Hohenpeissenberg Aerosol Formation Experiment (HAFEX) carried out in 1998–2000.
A clear correlation between the particle formation rate and the sulphuric acid
concentration to the power from one to two was identified. For each of the
analysed 45 particle formation days, we evaluated the coefficients quantifying
this coupling in activation and kinetic nucleation theories, predicting linear
and squared dependencies, respectively. The median activation and kinetic
coefficients were 1.6 x 10^–7 s^–1 and 3.2 x
10^–14 cm³ s^–1. The daily values of the
coefficients varied within two orders of magnitude and, even during one day, the
observed formation rates fluctuated around the predicted rates. A squared
dependency was almost as frequent as linear, but the kinetic coefficient
anticorrelated with sulphuric acid concentration. This anticorrelation and the
variation of the coefficients could be related to the observed correlation
between the coefficients and monoterpene oxidation product
concentrations.