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

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

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-6-9187-2006 ◽

2006 ◽

Vol 6 (5) ◽

pp. 9187-9212

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 269 and 226 particle formation days for negative and positive intermediate ions, respectively. For negatively charged particles we classified 411 undefined and 349 non-event days whereas for positively charged particles 342 undefined and 461 non-event days. The results were compared with the ordinary classification based on 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 104 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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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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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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The ECOMA 2007 campaign: rocket observations and numerical modelling of aerosol particle charging and plasma depletion in a PMSE/NLC layer

Annales Geophysicae ◽

10.5194/angeo-27-781-2009 ◽

2009 ◽

Vol 27 (2) ◽

pp. 781-796 ◽

Cited By ~ 17

Author(s):

A. Brattli ◽

Ø. Lie-Svendsen ◽

K. Svenes ◽

U.-P. Hoppe ◽

I. Strelnikova ◽

...

Keyword(s):

Aerosol Particle ◽

Aerosol Particles ◽

Pure Water ◽

Ion Density ◽

Ambient Plasma ◽

Water Ice ◽

Charged Aerosol ◽

Summer Echoes ◽

Polar Mesosphere Summer Echoes ◽

Positively Charged

Abstract. The ECOMA series of rocket payloads use a set of aerosol particle, plasma, and optical instruments to study the properties of aerosol particles and their interaction with the ambient plasma environment in the polar mesopause region. In August 2007 the ECOMA-3 payload was launched into a region with Polar Mesosphere Summer Echoes (PMSE) and noctilucent clouds (NLC). An electron depletion was detected in a broad region between 83 and 88 km, coincident with enhanced density of negatively charged aerosol particles. We also find evidence for positive ion depletion in the same region. Charge neutrality requires that a population of positively charged particles smaller than 2 nm and with a density of at least 2×108 m−3 must also have been present in the layer, undetected by the instruments. A numerical model for the charging of aerosol particles and their interaction with the ambient plasma is used to analyse the results, showing that high aerosol particle densities are required in order to explain the observed ion density depletion. The model also shows that a very high photoionisation rate is required for the particles smaller than 2 nm to become positively charged, indicating that these may have a lower work function than pure water ice.

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

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-709-2007 ◽

2007 ◽

Vol 7 (1) ◽

pp. 709-751

Author(s):

T. M. Ruuskanen ◽

M. Kaasik ◽

P. P. Aalto ◽

U. Hõrrak ◽

M. Vana ◽

...

Keyword(s):

Kola Peninsula ◽

Aerosol Particle ◽

Particle Deposition ◽

Aerosol Particles ◽

Particle Formation ◽

Nucleation Event ◽

Air Ions ◽

Field Station ◽

Air Mass ◽

Measurement Campaign

Abstract. The LAPBIAT measurement campaign took place in the 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 polluted air mass approaching from industrial areas of Kola Peninsula, Russia. 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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Investigation on the role of elevated gamma radiation in ion production during precipitation

10.5194/egusphere-egu21-11909 ◽

2021 ◽

Author(s):

Xuemeng Chen ◽

Susana Barbosa ◽

Jussi Paatero ◽

Markku Kulmala ◽

Heikki Junninen

Keyword(s):

Gamma Radiation ◽

Large Scale ◽

Size Range ◽

Aerosol Particles ◽

Particle Formation ◽

Precipitation Intensity ◽

Ion Concentration ◽

Atmospheric Measurements ◽

Air Ions ◽

Development Fund

Air ions are ubiquitous in the atmosphere. These charge carriers can be found in various forms as charged molecules, nanoclusters as well as aerosol particles. The population of air ions normally concentrates in the cluster size range (0.8 &#8211; 1.7 nm in mobility equivalent diameters) in the absence of particle formation processes. A concentration burst in the intermediate size range (1.7 &#8211; 7 nm) can be typically observed during atmospheric new particle formation (NPF) and in precipitation episodes 1. Contrary to the intermediate ions formed during NPF that favour growth to larger sizes, intermediate ion bursts resulting from precipitation tend to shrink 2,3. The production of intermediate ions during precipitation has been attributed to the Lenard effect and they are usually referred to as the balloelectric ions 3.During precipitation the rain-out and wash-out of radon progeny increase the gamma dose at ground level 4. Being a type of ionising radiation, gamma creates positive and negative charges in the air. These charges are either lost in recombination or transformed into air ions. It is therefore interesting to understand whether the precipitation-associated elevation in gamma radiation plays any role in forming or neutralising the balloelectric ions. At SMEAR II station in Hyyti&#228;l&#228;, Finland 5, we have conducted measurements of air ions, gamma radiation, precipitation together with other meteorological parameters. A similar establishment of the measurement set stands also at SMEAR Estonia station in Jarvselj&#228;, Estonia 6. The data collected at Hyyti&#228;l&#228; from 2017.7 to 2018.8 show that the intermediate ion concentration correlates with rainfall only when the precipitation intensity is greater than 1 mm/h. For milder rainfall with the precipitation intensity being 0.1-1 mm/h, the intermediate ion concentration increases with an increase in the gamma counts. The work is under progress and we intend to extend the analysis to Jarvselj&#228; data for a comprehensive understanding of the observations.Acknowledgements: This work received financial supports from European Regional Development Fund (project MOBTT42) under the Mobilitas Pluss programme and from Estonian Research Council project PRG714.References:1. Tammet, H., Komsaare, K. & H&#245;rrak, U. Intermediate ions in the atmosphere. Atmospheric Research 135-136, 263-273, doi:10.1016/j.atmosres.2012.09.009 (2014).2. H&#245;rrak, U. et al. Formation of Charged Nanometer Aerosol Particles Associated with Rainfall: Atmospheric Measurements and Lab Experiment. Report Series in Aerosol Science 80, 180-185 (2006).3. Tammet, H., H&#245;rrak, U. & Kulmala, M. Negatively charged nanoparticles produced by splashing of water. Atmos. Chem. Phys. 9, 357&#8211;367 (2009).4. Paatero, J. & Hatakka, J. Wet deposition efficiency of short-lived radon-222 progeny in central Finland. Boreal Env. Res. 4, 285-293 (1999).5. Hari, P. & Kulmala, M. Station for measuring ecosystem-atmosphere relations (SMEAR II). Boreal Environ. Res. 10, 315-322 (2005).6. Noe, S. M. et al. SMEAR Estonia: Perspectives of a large-scale forest ecosystem &#8211; atmosphere research infrastructure. Forestry Studies 63, doi:10.1515/fsmu-2015-0009 (2015).

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Annual and interannual variation in boreal forest aerosol particle number and volume concentration and their connection to particle formation

Tellus B ◽

10.3402/tellusb.v60i4.16940 ◽

2008 ◽

Vol 60 (4) ◽

Author(s):

Miikka Dal Maso ◽

Antti Hyvärinen ◽

Mika Komppula ◽

Peter Tunved ◽

Veli-Matti Kerminen ◽

...

Keyword(s):

Boreal Forest ◽

Aerosol Particle ◽

Interannual Variation ◽

Particle Number ◽

Volume Concentration ◽

Particle Formation

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Laser ablation aerosol particle time-of-flight mass spectrometer (LAAPTOF): performance, reference spectra and classification of atmospheric samples

Atmospheric Measurement Techniques ◽

10.5194/amt-11-2325-2018 ◽

2018 ◽

Vol 11 (4) ◽

pp. 2325-2343 ◽

Cited By ~ 11

Author(s):

Xiaoli Shen ◽

Ramakrishna Ramisetty ◽

Claudia Mohr ◽

Wei Huang ◽

Thomas Leisner ◽

...

Keyword(s):

Laser Ablation ◽

Aerosol Particle ◽

Mass Spectrometer ◽

Size Range ◽

Aerosol Particles ◽

Time Of Flight ◽

Polystyrene Latex ◽

Dust Particles ◽

Data Set ◽

Flight Mass Spectrometer

Abstract. The laser ablation aerosol particle time-of-flight mass spectrometer (LAAPTOF, AeroMegt GmbH) is able to identify the chemical composition and mixing state of individual aerosol particles, and thus is a tool for elucidating their impacts on human health, visibility, ecosystem, and climate. The overall detection efficiency (ODE) of the instrument we use was determined to range from ∼  (0.01 ± 0.01) to ∼  (4.23 ± 2.36) % for polystyrene latex (PSL) in the size range of 200 to 2000 nm, ∼  (0.44 ± 0.19) to ∼  (6.57 ± 2.38) % for ammonium nitrate (NH4NO3), and ∼  (0.14 ± 0.02) to ∼  (1.46 ± 0.08) % for sodium chloride (NaCl) particles in the size range of 300 to 1000 nm. Reference mass spectra of 32 different particle types relevant for atmospheric aerosol (e.g. pure compounds NH4NO3, K2SO4, NaCl, oxalic acid, pinic acid, and pinonic acid; internal mixtures of e.g. salts, secondary organic aerosol, and metallic core–organic shell particles; more complex particles such as soot and dust particles) were determined. Our results show that internally mixed aerosol particles can result in spectra with new clusters of ions, rather than simply a combination of the spectra from the single components. An exemplary 1-day ambient data set was analysed by both classical fuzzy clustering and a reference-spectra-based classification method. Resulting identified particle types were generally well correlated. We show how a combination of both methods can greatly improve the interpretation of single-particle data in field measurements.

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Hygroscopic properties of ultrafine aerosol particles in the boreal forest: diurnal variation, solubility and the influence of sulfuric acid

Atmospheric Chemistry and Physics ◽

10.5194/acp-7-211-2007 ◽

2007 ◽

Vol 7 (1) ◽

pp. 211-222 ◽

Cited By ~ 82

Author(s):

M. Ehn ◽

T. Petäjä ◽

H. Aufmhoff ◽

P. Aalto ◽

K. Hämeri ◽

...

Keyword(s):

Sulfuric Acid ◽

Boreal Forest ◽

Diurnal Variation ◽

Gas Phase ◽

Aerosol Particles ◽

Particle Formation ◽

Time Of Day ◽

New Particle Formation ◽

Hygroscopic Growth ◽

Hygroscopic Properties

Abstract. The hygroscopic growth of aerosol particles present in a boreal forest was measured at a relative humidity of 88%. Simultaneously the gas phase concentration of sulfuric acid, a very hygroscopic compound, was monitored. The focus was mainly on days with new particle formation by nucleation. The measured hygroscopic growth factors (GF) correlated positively with the gaseous phase sulfuric acid concentrations. The smaller the particles, the stronger the correlation, with r=0.20 for 50 nm and r=0.50 for 10 nm particles. The increase in GF due to condensing sulfuric acid is expected to be larger for particles with initially smaller masses. During new particle formation, the changes in solubility of the new particles were calculated during their growth to Aitken mode sizes. As the modal diameter increased, the solubility of the particles decreased. This indicated that the initial particle growth was due to more hygroscopic compounds, whereas the later growth during the evening and night was mainly caused by less hygroscopic or even hydrophobic compounds. For all the measured sizes, a diurnal variation in GF was observed both during days with and without particle formation. The GF was lowest at around midnight, with a mean value of 1.12–1.24 depending on particle size and if new particle formation occurred during the day, and increased to 1.25–1.34 around noon. This can be tentatively explained by day- and nighttime gas-phase chemistry; different vapors will be present depending on the time of day, and through condensation these compounds will alter the hygroscopic properties of the particles in different ways.

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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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