Statistical characterization of air ion mobility spectra at Tahkuse Observatory: Classification of air ions

摘要: A database of 8615 hourly averaged air ion mobility spectra in the range 0.00041–3.2 cm2 V−1 s−1 was measured at Tahkuse Observatory, Estonia, during 14 months 1993–1994. The average spectrum over whole period shows distinct peaks small and large ions. Intermediate ions with mobilities 0.034–0.5 are low concentration about 50 cm−3 spectrum. They experience occasional bursts up to 900 6–10 hours daytime. number burst events recorded 101, maximum frequency spring minimum winter. Physically, intermediate can be called aerosol ions, cluster principal component analysis applied detect structure an As a result, (diameters 0.36–79 nm) divided into five classes: cluster, big intermediate, light large, heavy boundaries between classes 1.3 (diameter 0.85 nm), 0.5 (1.6 0.034 (7.4 0.0042 (22 nm). components that closely correlated respective explain 92% total variance. classification is accord three-modal size submicron particles.