Observations of aerosol-cloud interactions at the Puijo semi-urban measurement station

Harri Portin, Mika Komppula, Ari Leskinen, Sami Romakkaniemi, Ari Laaksonen, Kari Lehtinen, H Portin, M Komppula, A Leskinen, S Romakkaniemi, A Laaksonen, K Lehtinen
2009 unpublished
2009: Observations of aerosol-cloud interactions at the Puijo semi-urban measurement station. Boreal Env. Res. 14: 641-653. The Puijo measurement station has produced continuous data on aerosol-cloud interactions since June 2006. The station is located on the top fl oor of an observation tower in a semi-urban environment near the town of Kuopio in central Finland. The top of the tower (306 m a.s.l.) has been detected to be in-cloud approximately 10% of the time. We analysed continuous weather,
more » ... ontinuous weather, particle size distribution and cloud droplet size distribution measurements. The effects of local pollutant sources and air mass origin on aerosol-cloud interaction were examined in detail. We were able to fi nd clear evidence of the aerosol indirect effects at the Puijo site. There is a positive correlation between cloud droplet number concentration and particle number concentration. Higher cloud droplet concentration led to a smaller average cloud droplet size. Furthermore, the ratio of cloud droplet number concentration to accumulation mode particle number concentration is smaller when the particle number concentration is higher. Results from our trajectory analysis indicated that at our site marine air masses had higher particle concentrations and the continental aerosols are more effective in acting as cloud condensation nuclei than marine aerosols, probably due to their larger mean size. We could also distinguish the effect of local pollutant sources.