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Helsinki station is a typical urban background station. Aerosol particle concentration is governed mainly by the local activities (weekday-weekend, traffic), meteorological conditions (mixing height, wind speed, inversion situation) and long range transport (North Atlantic or Eastern Europe air masses).

Hyytiälä station is a rural boreal forest station with some local pollution from the near-by field station and a local village five kilometres away. Particle concentrations is governed by local production by nucleation (Events) and long range transport.

Värriö station is a remote subarctic station. Particle concentrations is governed by local production by nucleation (Events) and long range transport (Kola peninsula).

Particle size distribution from Helsinki station

Particle size distributions are measured with Differential mobility particle sizers (DMPS). The instrument classifies the particles according to their electrical mobility, which is dependent on the particle size and charge. The first plot presents the particle number size distribution. Size is on the y-axis and time on the x-axis. Particle concentration is on the z-axis. The more red the colour is the more particles there exists in the given size class and time. Particles transported to the site further away have typically size around 100nm or more. Particles produced locally by traffic have size between 10 and 100 nm. Particles produced locally in the near future by gas to particle formation have a diameter less than 10nm when they are "fresh". With time more material condense on them and their size increases ("banana curve")

DMPS log

Helsinki APS

Particle size distribution from Hyytiälä station

DMPS log

Hyytiälä APS

Particle scattering coefficient data from Hyytiälä station

Particle scattering coefficient is measured with Nephelometer (TSI 3563). The scattering coefficient is measured with three different wave lengths in the angle from 7 to 170 degrees. The backscatter signal (the lower curves) is measured in the angle from 7 to 90 degrees. The coefficient depends on particle concentration, size and colour. High scattering coefficients are observed typically when there is a lot of particles in the accumulation mode size range (around 200nm), (air mass from Eastern Europe, forest fires)
nep

Aerosol black carbon concentration from Hyytiälä station

Aethalometer is measuring absorption coefficient of the aerosol particles. The more black the particles are, the more they absorb light. Carbon compounds absorb light well. These compounds are originated from traffic (diesel), biomass burning (sauna) and forest fires. Scattering coefficient and absorption coefficient are important quantities in climate change (direct climate forcing).