Abstrakt
The most important processes of atmospheric aerosol (AA) and cloud interactions are particle release during cloud dissipation, and wet scavenging (Laakso, 2003). The wet scavenging can be generally divided into in-cloud (ICS) and below-cloud (BCS) scavenging.
In this work, influence of both ICS and BCS on submicron AA has been studied on data measured at a rural background station Košetice, Czech Republic in five-year period from 5/2008 to 4/2013. The ICS processes were studied on atmospheric obscurities (mist, shallow fog, fog), while BCS processes were studied on atmospheric precipitation events, both liquid and solid (drizzle, rain, rain mixed with snow, snow).
The AA has been measured with SMPS (Scanning Mobility Particle Sizer, IfT-type) with time resolution of 5 minutes in size range from 10 to 800 nm. The AA concentrations during individual meteorological phenomena (observed by a professional meteorologist) were compared to the concentration measured during period without any recorded phenomenon, and also between each other.
Both obscurities and precipitation have a strong influence on AA concentrations - total number concentrations measured during any mentioned phenomenon are lower than the concentrations measured at non-phenomenon periods (Fig. 1). Generally, during precipitation events, AA concentrations are lower than during obscurities.
However, there is a further variability among individual phenomena. The difference in effect of the hydrometeors on AA is not only in terms of total concentrations, though.
Both precipitation and obscuration have a strong influence on particle number size distributions, PNSD, (Fig. 2).