A CRITICAL-REVIEW OF BELOW-CLOUD AEROSOL SCAVENGING RESULTS ON MT RIGI

One of the main goals of the 7-year winter precipitation field study o n ML Rigi (central Switzerland) was a better understanding of the mech anisms leading to the wet removal of aerosol particles from the atmosp here. A critical review of the main below-cloud scavenging results of this event-oriented multidisciplinary project is given. The Mt. Rigi r esults are compared with a theoretical model applied to experimentally determined initial and boundary conditions and with literature report s on similar field studies. For submicron particles significant discre pancies have been found between experiment and theory, our measurement s showing scavenging coefficients 20 to 40 times higher on average tha n model predictions. An attempt is made to explain the differences res ulting from these two different approaches. There is some evidence tha t this may arise partly as a result of humidity effects, but other inf luences are discussed as well.