Composition and concentrations of aerosol precursor gases in the sub-Arctic boreal forest

2021 ◽  
Author(s):  
Tuija Jokinen ◽  
Katrianne Lehtipalo ◽  
Kimmo Neitola ◽  
Nina Sarnela ◽  
Totti Laitinen ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Sulfuric Acid ◽  
Ambient Air ◽  
Particle Formation ◽  
The Arctic ◽  
New Particle Formation ◽  
Aerosol Formation ◽  
Iodic Acid ◽  
Field Station

<p>One way to form aerosol particles is the condensation of oxidized atmospheric trace gases, such as sulfuric acid (SA) into small molecular clusters. After growing to larger particles by condensation of low volatile gases, they can affect the planets climate directly by scattering light and indirectly by acting as cloud condensation nuclei. Observations of low-volatility aerosol precursor gases have been reported around the world but long-term measurement series and Arctic data sets showing seasonal variation are close to non-existent. In here, we present ~7 months of aerosol precursor gas measurements performed with the nitrate based chemical ionization mass spectrometer (CI-APi-TOF). We deployed our measurements ~250 km above the Arctic Circle at the Finnish sub-Arctic field station, SMEAR I in Värriö. We report concentration measurements of the most common new particle formation related compounds; sulfuric acid, methanesulfonic acid (MSA), iodic acid (IA) and highly oxygenated organic compounds, HOMs. At this remote measurement site, surrounded by a strict nature preserve, that gets occasional pollution from a Russian city of Murmansk, SA is originated both from anthropogenic and biological sources and has a clear diurnal cycle but no significant seasonal variation, while MSA as an oxidation product of purely biogenic sources is showing a more distinct seasonal cycle. Iodic acid concentrations are the most stable throughout the measurement period, showing almost identical peak concentrations for spring, summer and autumn. HOMs are abundant during the summer months and due to their high correlation with ambient air temperature, we suggest that most of HOMs are products of monoterpene oxidation. New particle formation events at SMEAR I happen under relatively low temperatures, low relative humidity, high ozone concentration, high SA concentration in the morning and high MSA concentrations in the afternoon. The role of HOMs in aerosol formation will be discussed. All together, these are the first long term measurements of aerosol forming precursor from the sub-arctic region helping us to understand atmospheric chemical processes and aerosol formation in the rapidly changing Arctic.</p><p> </p><p> </p>

scholarly journals Measurement report: Long-term measurements of aerosol precursor concentrations in the Finnish sub-Arctic boreal forest

2021 ◽  
Author(s):  
Tuija Jokinen ◽  
Katrianne Lehtipalo ◽  
Roseline Cutting Thakur ◽  
Ilona Ylivinkka ◽  
Kimmo Neitola ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Ambient Air ◽  
Particle Formation ◽  
The Arctic ◽  
Ionization Mass ◽  
New Particle Formation ◽  
Aerosol Formation ◽  
Iodic Acid ◽  
Field Station

Abstract. Aerosol particles form in the atmosphere by clustering of certain atmospheric vapors. After growing to larger particles by condensation of low volatile gases, they can affect the Earth’s climate directly by scattering light and indirectly by acting as cloud condensation nuclei. Observations of low-volatility aerosol precursor gases have been reported around the world but longer-term measurement series and any Arctic data sets showing seasonal variation are close to non-existent. In here, we present ~7 months of aerosol precursor gas measurements performed with the nitrate based chemical ionization mass spectrometer (CI-APi-TOF). We deployed our measurements ~150 km North of the Arctic Circle at the continental Finnish sub-Arctic field station, SMEAR I, located in Värriö strict nature reserve. We report concentration measurements of the most common new particle formation related compounds; sulfuric acid (SA), methane sulfonic acid (MSA), iodic acid (IA) and a total concentration of highly oxygenated organic compounds (HOMs). At this remote measurement site, SA is originated both from anthropogenic and biological sources and has a clear diurnal cycle but no significant seasonal variation. MSA shows a more distinct seasonal cycle with concentrations peaking in the summer. Of the measured compounds, iodic acid concentrations are the most stable throughout the measurement period, except in April, when the concentration of IA is significantly higher than during the rest of the year. Otherwise, IA has almost identical daily maximum concentrations in spring, summer and autumn, and on new particle formation event or non-event days. HOMs are abundant during the summer months and low in winter months. Due to the low winter concentrations and their high correlation with ambient air temperature, we suggest that most of HOMs are products of biogenic emissions, most probably monoterpene oxidation products. New particle formation events at SMEAR I happen under relatively low temperatures with a fast temperature rise in the morning followed by decreasing relative humidity during the day. The ozone concentrations are on average ~10 ppbv higher on NPF days than non-event days. During NPF days, we have on average higher SA concentration peaking at noon, higher MSA concentrations in the afternoon and slightly higher IA concentration than during non-event days. All together, these are the first long term measurements of aerosol forming vapors from the SMEAR I in the sub-arctic region, and the results help us to understand atmospheric chemical processes and aerosol formation in the rapidly changing Arctic.

scholarly journals Trends in new particle formation in eastern Lapland, Finland: effect of decreasing sulfur emissions from Kola Peninsula

2014 ◽  
Vol 14 (9) ◽  
pp. 4383-4396 ◽  
Author(s):  
E.-M. Kyrö ◽  
R. Väänänen ◽  
V.-M. Kerminen ◽  
A. Virkkula ◽  
T. Petäjä ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Kola Peninsula ◽  
Formation Rate ◽  
Particle Formation ◽  
The Arctic ◽  
Late Winter ◽  
Rapid Decline ◽  
New Particle Formation ◽  
Sulfur Species ◽  
Sulfur Emissions

Abstract. The smelter industry in Kola Peninsula is the largest source of anthropogenic SO2 in the Arctic part of Europe and one of the largest within the Arctic domain. Due to socio-economic changes in Russia, the emissions have been decreasing especially since the late 1990s resulting in decreased SO2 concentrations close to Kola in eastern Lapland, Finland. At the same time, the frequency of new particle formation days has been decreasing distinctively at SMEAR I station in eastern Lapland, especially during spring and autumn. We show that sulfur species, namely sulfur dioxide and sulfuric acid, have an important role in both new particle formation and subsequent growth and that the decrease in new particle formation days is a result of the reduction of sulfur emissions originating from Kola Peninsula. In addition to sulfur species, there are many other quantities, such as formation rate of aerosol particles, condensation sink and nucleation mode particle number concentration, which are related to the number of observed new particle formation (NPF) days and need to be addressed when linking sulfur emissions and NPF. We show that while most of these quantities exhibit statistically significant trends, the reduction in Kola sulfur emissions is the most obvious reason for the rapid decline in NPF days. Sulfuric acid explains approximately 20–50% of the aerosol condensational growth observed at SMEAR I, and there is a large seasonal variation with highest values obtained during spring and autumn. We found that (i) particles form earlier after sunrise during late winter and early spring due to high concentrations of SO2 and H2SO4; (ii) several events occurred during the absence of light, and they were connected to higher than average concentrations of SO2; and (iii) high SO2 concentrations could advance the onset of nucleation by several hours. Moreover, air masses coming over Kola Peninsula seemed to favour new particle formation.

scholarly journals Wintertime subarctic new particle formation from Kola Peninsula sulfur emissions

2021 ◽  
Vol 21 (23) ◽  
pp. 17559-17576
Author(s):  
Mikko Sipilä ◽  
Nina Sarnela ◽  
Kimmo Neitola ◽  
Totti Laitinen ◽  
Deniz Kemppainen ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Kola Peninsula ◽  
Cloud Condensation Nuclei ◽  
Particle Formation ◽  
Negative Ion ◽  
The Arctic ◽  
Size Distributions ◽  
New Particle Formation ◽  
So2 Emissions ◽  
Finnish Lapland

Abstract. The metallurgical industry in the Kola Peninsula, north-west Russia, form, after Norilsk, Siberia, the second largest source of air pollution in the Arctic and subarctic domain. Sulfur dioxide (SO2) emissions from the ore smelters are transported to wide areas, including Finnish Lapland. We performed investigations on concentrations of SO2, aerosol precursor vapours, aerosol and ion cluster size distributions together with chemical composition measurements of freshly formed clusters at the SMEAR I station in Finnish Lapland relatively close (∼ 300 km) to the Kola Peninsula industrial sites during the winter 2019–2020. We show that highly concentrated SO2 from smelter emissions is converted to sulfuric acid (H2SO4) in sufficient concentrations to drive new particle formation hundreds of kilometres downwind from the emission sources, even at very low solar radiation intensities. Observed new particle formation is primarily initiated by H2SO4–ammonia (negative-)ion-induced nucleation. Particle growth to cloud condensation nuclei (CCN) sizes was concluded to result from sulfuric acid condensation. However, air mass advection had a large role in modifying aerosol size distributions, and other growth mechanisms and condensation of other compounds cannot be fully excluded. Our results demonstrate the dominance of SO2 emissions in controlling wintertime aerosol and CCN concentrations in the subarctic region with a heavily polluting industry.

Observations of New Particle Formation events during summertime in Helsinki

2021 ◽  
Author(s):  
Roseline Thakur ◽  
Lubna Dada ◽  
Lisa Beck ◽  
Tommy Chan ◽  
Juha Sulo ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Urban Areas ◽  
Boreal Forests ◽  
Cloud Condensation Nuclei ◽  
Cyanobacterial Bloom ◽  
Particle Formation ◽  
Capital City ◽  
Atmospheric Conditions ◽  
New Particle Formation ◽  
Iodic Acid

<p>Aerosols can originate from different sources and undergo various formation pathways. New Particle formation (NPF) events occur when precursor vapors nucleate and vapors with low volatility condense on the critical nuclei enabling them to grow to cloud condensation nuclei (CCN) relevant sizes. As CCN, these aerosols affect the occurrence of clouds and their lifetime on local, regional and global level.  Many studies have investigated new particle formation events from various sites ranging from urban areas, boreal forests to pristine locations; however, there is still a dearth of studies investigating coastal new particle formation, which is a complex phenomenon due to the dynamic and ever-changing atmospheric conditions at the coast.  A comprehensive study of particle number distributions and aerosol forming precursor vapors was carried out in a coastal capital city of Finland, Helsinki, during the summer of 2019. The experimental setup comprising of a nitrate-based chemical ionization atmospheric pressure interface time of flight mass spectrometer (CI-APi-TOF), a neutral cluster-air ion spectrometer (NAIS) and a particle size magnifier (PSM) were housed in and around the SMEAR III station in Kumpula Science campus. SMEAR III is a unique site situated in a semi-urban yet coastal location. The period of experiment coincided with the cyanobacterial bloom in the coastal areas of Finland and in the Baltic Sea region. Our study recorded several regional NPF and aerosol burst events during this period. High concentrations of sulfuric acid was found to be associated with the regional NPF events whereas increasing iodic acid concentrations was mostly associated with the initiation of burst events. The sources of sulfuric acid and iodic acid has been carefully evaluated in this study.</p><p> </p>

Studies of the connection between condensable trace gases and aerosol particles in Svalbard

2021 ◽  
Author(s):  
Tuuli Lehmusjärvi ◽  
Roseline Thakur ◽  
Lisa Beck ◽  
Mikko Sipilä ◽  
Tuija Jokinen
Keyword(s):  
Cloud Condensation Nuclei ◽  
Regional Climate ◽  
High Arctic ◽  
Particle Formation ◽  
Urban Environments ◽  
The Arctic ◽  
New Particle Formation ◽  
Iodic Acid ◽  
Summer Time

<p>In the high Arctic, the climate is warming faster than in the lower latitudes due to the Arctic amplification. Sea ice is melting and permafrost is thawing, and the scarce vegetation of the Arctic is changing rapidly. All these varying conditions will have an impact on possible emission sources of aerosol precursor gases, thus affecting the New Particle Formation (NPF) in the Arctic atmosphere, of which we still know very little. It is important to study the NPF events, which parameters affect the aerosol phase and how these newly formed aerosols can grow into cloud condensation nuclei sizes. Only then, it is possible to understand how climate change is affecting the aerosol population, clouds and regional climate of the pristine Arctic. The role of the precursor gases like Sulphuric Acid (SA), Iodic Acid (IA), Methane Sulphonic Acid (MSA) and Highly Oxygenated organic Molecules (HOM) in NPF in boreal and urban environments has been explored to a great extent. However, the role of these precursor gases in NPF events in remote locations - devoid of pollution sources and the vegetation - is still ambiguous. Therefore, it is crucial to conduct long-term measurements to study the composition and concentrations of aerosol precursors molecules, nanoparticles and air ions in remote and climatically fragile place like Ny-Ålesund in the Arctic. This research location is not only a natural pristine laboratory to understand the atmospheric processes but also acts as a climate mirror reflecting the most drastic changes happening in the atmosphere and cryosphere. In this study, we aim to enhance the understanding of the role of aerosol precursor gases in new particle formation in Ny-Ålesund, Svalbard.</p><p>            We have studied aerosol particle formation now for almost three years in the Ny-Ålesund research village in Svalbard (78° 55' 24.7368'' N, 11° 54' 35.6220'' E.) with the Neutral cluster and Air Ion Spectrometer (NAIS) measuring ~1-40 nm particles and ions. We have conducted measurements with a Chemical Ionization Atmospheric Pressure interface Time Of Flight (CI-APi-TOF) mass spectrometer to understand the chemical composition of organic precursors vapours and abundance of inorganic aerosol precursor gases such as SA, MSA and IA. Additionally,  we have studied the emission and composition of volatile organic compounds on the site during summer-time.</p><p>            In this study, we report the time series concentrations of the most common aerosol precursor gases like SA, MSA, IA and HOM from the period 28.6.-25.7.2019, which are responsible for the initiation and/or growth of particles. The variability in the concentrations of these vapours is compared between NPF event and non-event days. The study explores also the role of meteorological parameters like wind speed, wind direction, temperature and humidity on NPF processes.</p>

scholarly journals Long-term observations of aerosol size distributions in semi-clean and polluted savannah in South Africa

2013 ◽  
Vol 13 (4) ◽  
pp. 1751-1770 ◽  
Author(s):  
V. Vakkari ◽  
J. P. Beukes ◽  
H. Laakso ◽  
D. Mabaso ◽  
J. J. Pienaar ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Diurnal Variation ◽  
Size Distribution ◽  
Aerosol Particles ◽  
Informal Settlements ◽  
Particle Formation ◽  
Dry Season ◽  
Size Distributions ◽  
New Particle Formation

Abstract. This study presents a total of four years of sub-micron aerosol particle size distribution measurements in the southern African savannah, an environment with few previous observations covering a full seasonal cycle and the size range below 100 nm. During the first 19 months, July 2006–January 2008, the measurements were carried out at Botsalano, a semi-clean location, whereas during the latter part, February 2008–May 2010, the measurements were carried out at Marikana (approximately 150 km east of Botsalano), which is a more polluted location with both pyrometallurgical industries and informal settlements nearby. The median total concentration of aerosol particles was more than four times as high at Marikana than at Botsalano. In the size ranges of 12–840 nm, 50–840 nm and 100–840 nm the median concentrations were 1856, 1278 and 698 particles cm−3 at Botsalano and 7805, 3843 and 1634 particles cm−3 at Marikana, respectively. The diurnal variation of the size distribution for Botsalano arose as a result of frequent regional new particle formation. However, for Marikana the diurnal variation was dominated by the morning and evening household burning in the informal settlements, although regional new particle formation was even more frequent than at Botsalano. The effect of the industrial emissions was not discernible in the size distribution at Marikana although it was clear in the sulphur dioxide diurnal pattern, indicating the emissions to be mostly gaseous. Seasonal variation was strongest in the concentration of particles larger than 100 nm, which was clearly elevated at both locations during the dry season from May to September. In the absence of wet removal during the dry season, the concentration of particles larger than 100 nm had a correlation above 0.7 with CO for both locations, which implies incomplete burning to be an important source of aerosol particles during the dry season. However, the sources of burning differ: at Botsalano the rise in concentration originates from regional wild fires, while at Marikana domestic heating in the informal settlements is the main source. Air mass history analysis for Botsalano identified four regional scale source areas in southern Africa and enabled the differentiation between fresh and aged rural background aerosol originating from the clean sector, i.e., western sector with very few large anthropogenic sources. Comparison to size distributions published for other comparable environments in Northern Hemisphere shows southern African savannah to have a unique combination of sources and meteorological parameters. The observed strong link between combustion and seasonal variation is comparable only to the Amazon basin; however, the lack of long-term observations in the Amazonas does not allow a quantitative comparison. All the data presented in the figures, as well as the time series of monthly mean and median size distributions are included in numeric form as a Supplement to provide a reference point for the aerosol modelling community.

scholarly journals Long-term observations of aerosol size distributions in semi-clean and polluted savannah in South Africa

2012 ◽  
Vol 12 (9) ◽  
pp. 24043-24093
Author(s):  
V. Vakkari ◽  
J. P. Beukes ◽  
H. Laakso ◽  
D. Mabaso ◽  
J. J. Pienaar ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Diurnal Variation ◽  
Size Distribution ◽  
Aerosol Particles ◽  
Informal Settlements ◽  
Particle Formation ◽  
Dry Season ◽  
Size Distributions ◽  
New Particle Formation

Abstract. This study presents a total of four years of sub-micron aerosol particle size distribution measurements in the Southern African savannah, an environment with few previous observations covering a full seasonal cycle and the size range below 100 nm. During the first 19 months, July 2006–January 2008, the measurements were carried out at Botsalano, a semi-clean location, whereas during the latter part, February 2008–May 2010, the measurements were carried out at Marikana (approximately 150 km east of Botsalano), which is a more polluted location with both pyrometallurgical industries and informal settlements nearby. The median total concentration of aerosol particles was more than four times as high at Marikana than at Botsalano. In the size ranges of 12–840 nm, 50–840 nm and 100–840 nm the median concentrations were 1850, 1280 and 700 particles cm−3 at Botsalano and 7800, 3800 and 1600 particles cm−3 at Marikana, respectively. The diurnal variation of the size distribution for Botsalano arose as a result of frequent regional new particle formation. However, for Marikana the diurnal variation was dominated by the morning and evening household burning in the informal settlements, although regional new particle formation was even more frequent than at Botsalano. The effect of the industrial emissions was not discernible in the size distribution at Marikana although it was clear in the sulphur dioxide diurnal pattern, indicating the emissions to be mostly gaseous. Seasonal variation was strongest in the concentration of particles larger than 100 nm, which was clearly elevated at both locations during the dry season from May to September. In the absence of wet removal during the dry season the concentration of particles larger than 100 nm had a correlation above 0.7 with CO for both locations, which implies incomplete burning to be an important source of aerosol particles during the dry season. However, the sources of burning differ: at Botsalano the rise in concentration originates from regional wild fires, while at Marikana domestic heating in the informal settlements is the main source. Air mass history analysis for Botsalano identified four regional scale source areas in Southern Africa and enabled the differentiation between fresh and aged rural background aerosol originating from the clean sector, i.e., western sector with very few large anthropogenic sources. Comparison to size distributions published for other comparable environments in Northern Hemisphere shows Southern African savannah to have a unique combination of sources and meteorological parameters. The observed strong link between combustion and seasonal variation is comparable only to the Amazon basin; however the lack of long-term observations in the Amazonas does not allow a quantitative comparison. All the data presented in the figures, as well as the time series of monthly mean and median size distributions are included in numeric form as a Supplement to provide a reference point for the aerosol modelling community.

scholarly journals Long-term measurement of sub-3 nm particles and their precursor gases in the boreal forest

2021 ◽  
Vol 21 (2) ◽  
pp. 695-715
Author(s):  
Juha Sulo ◽  
Nina Sarnela ◽  
Jenni Kontkanen ◽  
Lauri Ahonen ◽  
Pauli Paasonen ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Boreal Forest ◽  
Atmospheric Pressure ◽  
Particle Formation ◽  
New Particle Formation ◽  
Seasonal Differences ◽  
Size Classes ◽  
Autumn And Winter ◽  
Long Term Measurement

Abstract. The knowledge of the dynamics of sub-3 nm particles in the atmosphere is crucial for our understanding of the first steps of atmospheric new particle formation. Therefore, accurate and stable long-term measurements of the smallest atmospheric particles are needed. In this study, we analyzed over 5 years of particle concentrations in size classes 1.1–1.7 and 1.7–2.5 nm obtained with the particle size magnifier (PSM) and 3 years of precursor vapor concentrations measured with the chemical ionization atmospheric pressure interface time-of-flight mass spectrometer (CI-APi-ToF) at the SMEAR II station in Hyytiälä, Finland. The results show that there are significant seasonal differences in median concentrations of sub-3 nm particles, but the two size classes behave partly differently. The 1.1–1.7 nm particle concentrations are highest in summer, while the 1.7–2.5 nm particle concentrations are highest in springtime. The 1.7–2.5 nm particles exhibit a daytime maximum in all seasons, while the 1.1–1.7 nm particles have an additional evening maximum during spring and summer. Aerosol precursor vapors have notable diurnal and seasonal differences as well. Sulfuric acid and highly oxygenated organic molecule (HOM) monomer concentrations have clear daytime maxima, while HOM dimers have their maxima during the night. HOM concentrations for both monomers and dimers are the highest during summer and the lowest during winter following the biogenic activity in the surrounding forest. Sulfuric acid concentrations are the highest during spring and summer, with autumn and winter concentrations being 2 to 3 times lower. A correlation analysis between the sub-3 nm concentrations and aerosol precursor vapor concentrations indicates that both HOMs (particularly their dimers) and sulfuric acid play a significant role in new particle formation in the boreal forest. Our analysis also suggests that there might be seasonal differences in new particle formation pathways that need to be investigated further.

scholarly journals Ion-induced sulfuric acid–ammonia nucleation drives particle formation in coastal Antarctica

2018 ◽  
Vol 4 (11) ◽  
pp. eaat9744 ◽  
Author(s):  
T. Jokinen ◽  
M. Sipilä ◽  
J. Kontkanen ◽  
V. Vakkari ◽  
P. Tisler ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Particle Growth ◽  
Field Studies ◽  
Particle Formation ◽  
New Particle Formation ◽  
Aerosol Formation ◽  
Radiative Balance ◽  
Secondary Aerosol

Formation of new aerosol particles from trace gases is a major source of cloud condensation nuclei (CCN) in the global atmosphere, with potentially large effects on cloud optical properties and Earth’s radiative balance. Controlled laboratory experiments have resolved, in detail, the different nucleation pathways likely responsible for atmospheric new particle formation, yet very little is known from field studies about the molecular steps and compounds involved in different regions of the atmosphere. The scarcity of primary particle sources makes secondary aerosol formation particularly important in the Antarctic atmosphere. Here, we report on the observation of ion-induced nucleation of sulfuric acid and ammonia—a process experimentally investigated by the CERN CLOUD experiment—as a major source of secondary aerosol particles over coastal Antarctica. We further show that measured high sulfuric acid concentrations, exceeding 107 molecules cm−3, are sufficient to explain the observed new particle growth rates. Our findings show that ion-induced nucleation is the dominant particle formation mechanism, implying that galactic cosmic radiation plays a key role in new particle formation in the pristine Antarctic atmosphere.

scholarly journals Arctic aerosol life cycle: linking aerosol size distributions observed between 2000 and 2010 with air mass transport and precipitation at Zeppelin station, Ny-Ålesund, Svalbard

2012 ◽  
Vol 12 (11) ◽  
pp. 29967-30019 ◽  
Author(s):  
P. Tunved ◽  
J. Ström ◽  
R. Krejci
Keyword(s):  
Seasonal Variation ◽  
Size Distribution ◽  
Particle Formation ◽  
Meteorological Conditions ◽  
The Arctic ◽  
New Particle Formation ◽  
Accumulation Mode ◽  
Source Areas ◽  
Number Size Distribution ◽  
Arctic Aerosol

Abstract. In this study we present a qualitative and quantitative assessment of more the 10 yr of aerosol number size distribution data observed in the Arctic environment (Mt Zeppelin (78°56' N, 11°53' E, 474 m a.s.l.), Ny Ålesund, Svalbard). We provide statistics on both seasonal and diurnal characteristics of the aerosol observations and conclude that the Arctic aerosol number size distribution and auxiliary parameters such as integral mass and surface have a very pronounced seasonal variation. This seasonal variation seems to be controlled by both dominating source as well as meteorological conditions in general. In principle, three distinctly different periods can be identified during the Arctic year: the haze period characterized by a dominating accumulation mode aerosol (March–May) followed by the sunlit summer period with low abundance of accumulation mode particles but high concentration of small particles which likely are recently and locally formed (June–August). The rest of the year is characterized by comparably low concentration of accumulation mode particles and negligible abundance of ultra fine particles (September–February). Minimum aerosol mass and number concentration is usually observed during September/October. We further show that the transition between the different regimes is fast, suggesting rapid change in conditions defining their appearance. A source climatology based on trajectory analysis is provided and it is shown that there is a strong seasonality of dominating source areas, with dominance of Eurasia during the autumn-winter period and dominance of North Atlantic air during the summer months. We also show that new particle formation events seem to be a rather common phenomenon during the Arctic summer, and this is the result of both photochemical production of nucleating/condensing species and low condensation sink. It is also suggested that wet removal play a key role in defining the Arctic aerosol year, and plays a crucial role for removal of accumulation mode size particles as well as it may play a pivotal role for facilitating the conditions favoring new particle formation events. In summary the aerosol Arctic year seems to be at least qualitatively predictable based on knowledge of seasonality of transport paths and associated source areas, meteorological conditions and removal processes.

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