MOBILITY SPECTRUM OF AIR IONS AT TAHKUSE-OBSERVATORY

Abstract

Mobility spectra of air ions have been measured at a rural site in Estonia during several periods. The annual average mobility spectrum of natural small air ions is presented. The concentrations of two groups of air ions with mobilities 0.32-0.5 cm2/(V s) and 0.5-2.5 cm2(V s) are not correlated; this fact indicates the different nature of the ions of the two groups. The air ions with mobilities 0.5-2.5 cm2/(V s) are interpreted as cluster ions and the air ions with mobilities 0.32-0.5 cm2/(V s) as charged aerosol particles that can be created in the process of ion-induced nucleation. A half-year average mobility spectrum of the large ions with mobilities 3.2 x 10(-4) - 1.5 x 10(-1) cm2/(V s) is presented. The spectrum is well interpreted on the basis of the average size distribution of aerosol particles and on the theory of diffusion charging of the particles.

Publication
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES

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