Research

The Finnish part of activities concentrates on use of ground station data and continuous monitoring in several stations in Northern Finland. The measurements are running continuously, and data is available to all participants of POLARCAT.

One specific aim in studies by University of Helsinki is the interaction between snowfall and aerosol particles

Submicron aerosol particles can leave from the wintertime atmosphere with different means:

• Below-cloud scavenging in which particles collide with falling snow flakes
• By CCN activation
• Dry deposition

In our study the effectiveness of snowflakes as scavenging hydrometeors will be studied and overall scavenging coefficient for aerosol particles of 3 up to 1000 nm radius will be calculated using DMPS (differential mobility particle sizer) and Vaisala FD12P weather sensor data from Hyytiälä SMEAR II (University of Helsinki) and Pallas (Finnish Meteorological Institute) research stations. From this dataset only stable conditions with no significant changes in relative humidity, temperature, pressure or wind speed and direction will be taken into account in order to avoid particle concentration changes in frontal zones and other disturbing meteorological phenomena.

Later on, we plan to extend the study to cover dry deposition and winter-time in-cloud scavenging. These studies are funded by Maj and Tor Nessling foundation.

Education

University of Helsinki kept, in co-operation with Finnish Meteorological Institute and NILU (Norway) a course “Arctic Air Pollution” 23.4.-4.5.2007 at Värriö SMEAR I station in eastern Lapland, Finland. The course focused on Arctic air pollution issues, and especially on deposition processes. Altogether, 12 students participated in the course.