Comparative study of nucleation mode aerosol particles and intermediate air ions formation events at three sites

Marko Vana

doi:10.1029/2003jd004413

Characterization of air ions in boreal forest air during BIOFOR III campaign

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-5-2749-2005 ◽

2005 ◽

Vol 5 (3) ◽

pp. 2749-2790 ◽

Cited By ~ 4

Author(s):

U. Hõrrak ◽

P. P. Aalto ◽

J. Salm ◽

J. M. Mäkelä ◽

L. Laakso ◽

...

Keyword(s):

Boreal Forest ◽

Correlation Coefficient ◽

Aerosol Particles ◽

Ion Pairs ◽

Ion Concentration ◽

Cluster Ions ◽

Statistical Characteristics ◽

Nucleation Event ◽

Air Ions ◽

20 Nm

Abstract. The behavior of the concentration of positive small (or cluster) air ions and naturally charged nanometer aerosol particles (aerosol ions) has been studied on the basis of measurements carried out in a boreal forest at the Hyytiälä SMEAR station, Finland, during the BIOFOR III campaign in spring 1999. Statistical characteristics of the concentrations of cluster ions, two classes of aerosol ions of the sizes of 2.5–8 nm and 8–ca 20 nm and the quantities that determine the balance of small ions in the atmosphere have been given for the nucleation event days and non-event days. The dependence of small ion concentration on the ion loss (sink) due to aerosol particles was investigated applying a model of bipolar diffusion charging of particles by small ions. The small ion concentration and the ion sink were closely correlated (correlation coefficient 87%) when the fog events and the hours of high relative humidity (above 97%), as well as nocturnal calms and weak wind (wind speed<0.6 m s-1 had been excluded. In the case of nucleation burst events, variations in the concentration of small positive ions were in accordance with the changes caused by the ion sink due to aerosols; no clear indication of positive ion depletion by ion-induced nucleation was found. The estimated average ionization rate of air at the Hyytiälä station in early spring, when the ground was partly covered with snow, was about 4.8 ion pairs cm-3 s-1. The study of the charging state of nanometer aerosol particles (2.5–8 nm) revealed a strong correlation (correlation coefficient 88%) between the concentrations of particles and their charged fraction (positive air ions) during nucleation bursts. The estimated charged fraction of particles, which varied from 3% to 6% considering various nucleation event days, confirms that these particles are almost quasi-steady state charged. Also the particles and air ions in the size range of 8–ca 20 nm showed a good qualitative consistency; the correlation coefficient was 92%.

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Characterization of positive air ions in boreal forest air at the Hyytiälä SMEAR station

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-9465-2007 ◽

2007 ◽

Vol 7 (4) ◽

pp. 9465-9517 ◽

Cited By ~ 5

Author(s):

U. Hõrrak ◽

P. P. Aalto ◽

J. Salm ◽

K. Komsaare ◽

H. Tammet ◽

...

Keyword(s):

Boreal Forest ◽

Correlation Coefficient ◽

Aerosol Particles ◽

Ion Pairs ◽

Coniferous Forest ◽

Ion Concentration ◽

Statistical Characteristics ◽

Nucleation Event ◽

Air Ions ◽

20 Nm

Abstract. The behavior of the concentration of positive small (or cluster) air ions and naturally charged nanometer aerosol particles (aerosol ions) has been studied on the basis of measurements carried out in a boreal forest at the Hyytiälä SMEAR station, Finland, during the BIOFOR III campaign in spring 1999. Statistical characteristics of the concentrations of cluster ions, two classes of aerosol ions of the sizes of 2.5–8 nm and 8–ca. 20 nm and the quantities that determine the balance of small ions in the atmosphere have been given for the nucleation event days and non-event days. The dependence of small ion concentration on the ion loss (sink) due to aerosol particles was investigated applying a model of bipolar diffusion charging of particles by small ions. The small ion concentration and the ion sink were closely correlated (correlation coefficient –87%) when the fog events and the hours of high relative humidity (above 95%), as well as nocturnal calms and weak wind (wind speed <0.6 m s−1) had been excluded. However, an extra ion loss term presumably due to small ion deposition on coniferous forest with a magnitude equal to the average ion loss to pre-existing particles is needed to explain the observations. Also the hygroscopic growth correction of measured aerosol particle size distributions was found to be necessary for proper estimation of the ion sink. In the case of nucleation burst events, variations in the concentration of small positive ions were in accordance with the changes caused by the ion sink due to aerosols; no clear indication of positive ion depletion by ion-induced nucleation was found. The estimated average ionization rate of the air at the Hyytiälä station in early spring, when the ground was partly covered with snow, was about 6 ion pairs cm−3 s−1. The study of the charging state of nanometer aerosol particles (2.5–8 nm) revealed a strong correlation (correlation coefficient 88%) between the concentrations of particles and positively charged particles (positive air ions) during nucleation bursts. The estimated charged fraction of particles, which varied from 3% to 6% considering various nucleation event days, confirms that these particles are almost quasi-steady state charged. Also the particles and air ions in the size range of 8–ca. 20 nm showed a good qualitative consistency; the correlation coefficient was 92%.

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Comparative Study of Square and Sine-Wave Excitation Methods for the Measurement of Aerosol Particles Charge and Size Distribution Using Phase Doppler Anemometry

IEEE Transactions on Instrumentation and Measurement ◽

10.1109/tim.2010.2082498 ◽

2011 ◽

Vol 60 (4) ◽

pp. 1397-1407 ◽

Cited By ~ 6

Author(s):

Lu Zhang ◽

Janusz Kulon

Keyword(s):

Comparative Study ◽

Size Distribution ◽

Aerosol Particles ◽

Sine Wave ◽

Wave Excitation ◽

Phase Doppler Anemometry

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Concentrations and fluxes of aerosol particles during the LAPBIAT measurement campaign at Värriö field station

Atmospheric Chemistry and Physics ◽

10.5194/acp-7-3683-2007 ◽

2007 ◽

Vol 7 (14) ◽

pp. 3683-3700 ◽

Cited By ~ 15

Author(s):

T. M. Ruuskanen ◽

M. Kaasik ◽

P. P. Aalto ◽

U. Hõrrak ◽

M. Vana ◽

...

Keyword(s):

Kola Peninsula ◽

Aerosol Particle ◽

Aerosol Particles ◽

Particle Formation ◽

Nucleation Event ◽

New Particle Formation ◽

Air Ions ◽

Field Station ◽

Air Mass ◽

Measurement Campaign

Abstract. The LAPBIAT measurement campaign took place in the Värriö SMEAR I measurement station located in Eastern Lapland in the spring of 2003 between 26 April and 11 May. In this paper we describe the measurement campaign, concentrations and fluxes of aerosol particles, air ions and trace gases, paying special attention to an aerosol particle formation event broken by a air mass change from a clean Arctic air mass with new particle formation to polluted one approaching from industrial areas of Kola Peninsula, Russia, lacking new particle formation. Aerosol particle number flux measurements show strong downward fluxes during that time. Concentrations of coarse aerosol particles were high for 1–2 days before the nucleation event (i.e. 28–29 April), very low immediately before and during the observed aerosol particle formation event (30 April) and increased moderately from the moment of sudden break of the event. In general particle deposition measurements based on snow samples show the same changes. Measurements of the mobility distribution of air ions showed elevated concentrations of intermediate air ions during the particle formation event. We estimated the growth rates in the nucleation mode size range. For particles <10 nm, the growth rate increases with size on 30 April. Dispersion modelling made with model SILAM support the conclusion that the nucleation event was interrupted by an outbreak of sulphate-rich air mass in the evening of 30 April that originated from the industry at Kola Peninsula, Russia. The results of this campaign highlight the need for detailed research in atmospheric transport of air constituents for understanding the aerosol dynamics.

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15.P.03 Comparative study on filtration efficiency of fibrous flexible and stiff spherical solid aerosol particles

Journal of Aerosol Science ◽

10.1016/0021-8502(94)90327-1 ◽

1994 ◽

Vol 25 ◽

pp. 193-194 ◽

Cited By ~ 1

Author(s):

Albert Podgórski

Keyword(s):

Comparative Study ◽

Aerosol Particles ◽

Filtration Efficiency ◽

Solid Aerosol

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Identification and classification of the formation of intermediate ions measured in boreal forest

Atmospheric Chemistry and Physics ◽

10.5194/acp-7-201-2007 ◽

2007 ◽

Vol 7 (1) ◽

pp. 201-210 ◽

Cited By ~ 92

Author(s):

A. Hirsikko ◽

T. Bergman ◽

L. Laakso ◽

M. Dal Maso ◽

I. Riipinen ◽

...

Keyword(s):

Boreal Forest ◽

Aerosol Particle ◽

Size Range ◽

Aerosol Particles ◽

Charged Particles ◽

Negative Ions ◽

Particle Formation ◽

Air Ions ◽

Charged Aerosol ◽

Positively Charged

Abstract. We have measured the size distributions of air ions (0.42–7.5 nm in diameter) with the Balanced Scanning Mobility Analyzer in boreal forest, in Southern Finland since spring 2003. The size range covers the size range of cluster ions (approximately 0.42–1.6 nm) and naturally charged nanometre aerosol particles (1.6–7.5 nm) or intermediate air ions. Based on the measurements from April 2003 to March 2006 we studied the characteristics of charged aerosol particle formation by classifying each day either as a particle formation event, undefined or non-event day. The principal of the classification, as well as the statistical description of the charged aerosol particle formation events are given. We found in total 270 (26% of the analysed days) and 226 (22% of the analysed days) particle formation days for negative and positive intermediate ions, respectively. For negatively charged particles we classified 411 (40% of the analysed days) undefined and 348 (34% of the analysed days) non-event days whereas for positively charged particles 343 (33% of the analysed days) undefined and 460 (45% of the analysed days) non-event days. The results were compared with the ordinary classification based on the Differential Mobility Particle Sizer (DMPS) measurements carried out at the same place. The above-presented values differed slightly from that found from the DMPS data, with a lower particle diameter of 3 nm. In addition, we have found the rain-induced intermediate ion bursts frequently. The rain effect was detected on 163 days by means of negative ions and on 105 days by positive ones. Another interesting phenomenon among the charged aerosol particles was the appearance and existence of intermediate ions during the snowfall. We observed this phenomenon 24 times with negatively charged particles and 21 times with positively charged ones during winter months (October–April). These intermediate air ions were seen during the snowfall and may be caused by ice crystals, although the origin of these intermediate ions is unclear at the moment.

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Variation and balance of positive air ion concentrations in a boreal forest

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-655-2008 ◽

2008 ◽

Vol 8 (3) ◽

pp. 655-675 ◽

Cited By ~ 34

Author(s):

U. Hõrrak ◽

P. P. Aalto ◽

J. Salm ◽

K. Komsaare ◽

H. Tammet ◽

...

Keyword(s):

Steady State ◽

Boreal Forest ◽

Correlation Coefficient ◽

Aerosol Particles ◽

Coniferous Forest ◽

Ionization Rate ◽

Ion Concentration ◽

Air Ions ◽

Ion Concentrations ◽

Charged Aerosol

Abstract. Air ions are characterized on the basis of measurements carried out in a boreal forest at the Hyytiälä SMEAR station, Finland, during the BIOFOR III campaign in spring 1999. The air ions were discriminated as small ions (charged molecular aggregates of the diameter of less than 2.5 nm), intermediate ions (charged aerosol particles of the diameter of 2.5–8 nm), and large ions (charged aerosol particles of the diameter of 8–20 nm). Statistical characteristics of the ion concentrations and the parameters of ion balance in the atmosphere are presented separately for the nucleation event days and non-event days. In the steady state, the ionization rate is balanced with the loss of small ions, which is expressed as the product of the small ion concentration and the ion sink rate. The widely known sinks of small ions are the recombination with small ions of opposite polarity and attachment to aerosol particles. The dependence of small ion concentration on the concentration of aerosol particles was investigated applying a model of the bipolar diffusion charging of particles by small ions. When the periods of relative humidity above 95% and wind speed less than 0.6 m s−1 were excluded, then the small ion concentration and the theoretically calculated small ion sink rate were closely negatively correlated (correlation coefficient −87%). However, an extra ion loss term of the same magnitude as the ion loss onto aerosol particles is needed for a quantitative explanation of the observations. This term is presumably due to the small ion deposition on coniferous forest. The hygroscopic growth correction of the measured aerosol particle size distributions was also found to be necessary for the proper estimation of the ion sink rate. In the case of nucleation burst events, the concentration of small positive ions followed the general balance equation, no extra ion loss in addition to the deposition on coniferous forest was detected, and the hypothesis of the conversion of ions into particles in the process of ion-induced nucleation was not proved. The estimated average ionization rate of the air at the Hyytiälä station in early spring, when the ground was partly covered with snow, was about 6 ion pairs cm−3 s−1. The study of the charging state of nanometer aerosol particles (diameter 2.5–8 nm) in the atmosphere revealed a strong correlation (correlation coefficient 88%) between the concentrations of particles neutralized in the aerosol spectrometer and naturally positively charged particles (air ions) during nucleation bursts. The charged fraction of particles varied from 3% to 6% in accordance with the hypothesis that the particles are quasi-steady state charged.

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Atmospheric radioactivity measurements at the SMEAR Estonia Station

10.5194/egusphere-egu2020-19757 ◽

2020 ◽

Author(s):

Heikki Junninen ◽

Jussi Paatero ◽

Urmas Hõrrak ◽

Xuemeng Chen

Keyword(s):

Gamma Radiation ◽

Dose Rate ◽

Aerosol Particles ◽

Chem Phys ◽

Gamma Dose ◽

Gamma Dose Rate ◽

Air Ions ◽

Atmospheric Radioactivity ◽

Atmospheric Radon ◽

Radioactivity Measurements

The SMEAR Estonia is a Station for Measuring Ecosystem-Atmosphere Relations (SMEAR). It is built on the same concept as the Finnish SMEAR stations [1] and belongs to the same measurement network. It is located in a hemiboreal forest at J&#228;rvselja, South-Eastern Estonia (58.2714 N, 27.2703 E at 36 m a.s.l.) [2]. The Estonian University of Life Sciences runs long-term measurements on meteorological parameters, trace gases and fluxes at the station. Atmospheric aerosol and air ions measurements are deployed by the University of Tartu (UT).&#160;&#160;Our main interest at UT lies in characterising atmospheric ions and aerosols, studying their connections to atmospheric new particle formation and cloud processes, and understanding the impacts of these processes on air quality, local weather and climate. Air ions are known to participate in forming atmospheric new particles [3]. Newly formed aerosol particles have the potential to modify cloud properties, once they reach big enough sizes via condensational and coagulational growth[4]. Air ions are primarily produced by the ionisation of air molecules, with the ionisation energy provided by natural radioactivity present in the atmosphere. The initial ionisation produces are subject to different dynamic processes, including charge transfer, clustering, coagulation and condensational growth [5]. At UT, we are launching a five-year project, starting from Jan. 2020, to investigate how atmosphere transforms the new-born air ions to climatically relevant aerosol particles. In order to get insights into the transformation process, atmospheric radioactivity measurements are crucial together with air ion and aerosol measurements.&#160;In the lower troposphere, ionization of the atmospheric originates from the decay of radon and other radioactive nuclides in the air and the Earth's crust as well as cosmic radiation. In collaboration with the Finnish Meteorological Institute, we initiated atmospheric radioactivity measurements at the SMEAR Estonia. The total gamma radiation (50 keV to 1.3 MeV) is measured with a gamma radiation meter (RADOS RD-02L) (since June 2019). The atmospheric radon is monitored using a filter-based Geiger-M&#252;ller counter (since Nov. 2019), which is a one-counter variation of an earlier design[6]. Atmospheric radon concentration is determined based on deposited beta activity. Preliminary results show that SMEAR Estonia (mean gamma dose rate = 0.03 uSv/h, mean radon conc. = 2.5 Bq/m3) has less ionization than SMEAR II station in Finland (mean gamma dose rate = 0.08 uSv/h, mean radon conc. = 2 Bq/m3). The linkage of this observation to air ion properties is under progress.References:[1]&#160;&#160;&#160;&#160;&#160;&#160; Hari P., Kulmala M., Boreal Environ. Res. 2005, 10, 315-322.[2]&#160;&#160;&#160;&#160;&#160;&#160; Noe S. M. et al., Forestry Studies 2015, 63.[3]&#160;&#160;&#160;&#160;&#160;&#160; Tammet H. et al., Atmospheric Research 2014, 135-136, 263-273.[4]&#160;&#160;&#160;&#160;&#160;&#160; Merikanto J. et al., Atmos. Chem. Phys. 2009, 9, 8601-8616.[5]&#160;&#160;&#160;&#160;&#160;&#160; Chen X. et al. Atmos. Chem. Phys. 2016, 16, 14297-14315.[6]&#160;&#160;&#160;&#160;&#160;&#160; Paatero J. et al., Radiat. Prot. Dosim. 1994, 54, 33-39.

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