Connection between new particle formation and sulphuric acid at Hohenpeissenberg (Germany) including the influence of organic compounds

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 × 10^-7 s^-1 and 3.2 × 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.