Marko Vana

Aerosol particle formation events and analysis of high growth rates observed above a subarctic wetland-forest mosaic

An analysis of particle formation (PF) events over a subarctic mire in northern Swedenwas performed, based on number– size distributions of atmospheric aerosol particles (10–500 nm in diameter) and ions (0.4–40 nm in Tammet diameter). We present classification statistics for PF events from measurements covering the period July 2005–September 2006, with a break over the winter period. The PF event frequency peaked during the summer months, in contrast to other Scandinavian sites where the frequency is highest during spring and autumn. Our analysis includes calculated growth rates and estimates of concentrations and production rates of condensing vapour, deduced from the growth rates and condensational sink calculations, using AIS and SMPS data. Particle formation events with high growth rates (up to 50 nm h-1) occurred repeatedly. In these cases, the newly formed nucleation mode particles were often only present for periods of a few hours. On several occasions, repeated particle formation events were observed within 1 d, with differences in onset time of a few hours. These high growth rates were only observed when the condensation sink was higher than 0.001 s-1.

Observations on nocturnal growth of atmospheric clusters

In this paper, we summarize recent observations of nighttime nucleation events observed during 4 yr, from 2003 to 2006, at the SMEAR II station in Hyytiäläa, southern Finland. Formation of new atmospheric aerosol particles has been frequently observed all around the world in daytime, but similar observations in nighttime are rare. The recently developed ion spectrometers enabled us to measure charged aerosol particles and ion clusters to diameters < 1 nm and are efficient tools for evaluating cluster dynamics during nighttime. We observed clear growth of cluster ions during approximately 60 nights per yr. The newly formed intermediate ions usually persisted for several hours with typical concentrations of 100–200 cm-3. The evolution of nighttime growth events is different compared with daytime events. The mechanism behind nighttime events is still unclear, but the behaviour can be described by the hypothesis of activation of clusters.

Air Ion Measurements During a Cruise from Europe to Antarctica

Latitudinal air ion mobility distribution variations were characterized in the marine boundary layer during a cruise over the Eastern Atlantic and Southern Ocean. We measured concentrations of cluster ions and charged aerosol particles in the size range of 0.4–40 nm. The measured ion mobility distributions were characterized and classified according to meteorological conditions and air mass back-trajectories. New particle formation episodes (bursts of intermediate air ions) were observed above the pack-ice region of the Southern Ocean and several times during showers in the tropical marine boundary layer.

SMEAR Estonia: Perspectives of a large-scale forest ecosystem – atmosphere research infrastructure

Abstract Establishment of the SMEAR Estonia at a hemiboreal mixed deciduous broad-leaved-evergreen needle-leaved forest at Järvselja, South-Eastern Estonia, has strongly enhanced the possibilities for national and international cooperation in the fields of forest ecosystem – atmosphere research and impacts of climatic changes on forest ecosystems, atmospheric trace gases, aerosols and air ions. The station provides a multitude of comprehensive continuously measured data covering key climatic and atmospheric characteristics (state and dynamics of solar radiation, trace gases, aerosols and air ions, meteorological parameters) and forest ecosystem traits (net primary productivity, individual tree growth, gas-exchange characteristics, soil variables). The station follows a multidisciplinary and multiscale approach covering processes in spatial dimensions ranging from nanometres to several hundred square kilometres, being thus able to significantly contribute to worldwide measurement networks and the SMEAR network. Here we present an overview of the station, its data produced and we envision future developments towards sustainable research and development of the large-scale scientific infrastructure SMEAR Estonia.

Air Ion Measurements at Mace Head on the West Coast of Ireland

Coastal nucleation events and behavior of cluster ions were characterized through the measurements of air ion mobility distributions at the Mace Head research station on the west coast of Ireland in 2006. We measured concentrations of cluster ions and charged aerosol particles in the size range of 0.4–40 nm. These measurements allow us to characterize freshly nucleated charged particles with diameter below 3 nm. The analysis shows that bursts of intermediate ions (1.6–7 nm) are a frequent phenomenon in marine coastal environment. Nucleation evens occurred during most of the measurement days. We classified the nucleation burst events. Particle formation and growth events mostly coincided with the presence of low tide. Small ions concentrations appear to be strongly dependent on the variations of meteorological parameters including wind speed and direction.