On the seasonal variation in observed size distributions in northern Europe and their changes with decreasing anthropogenic emissions in Europe: climatology and trend analysis based on 17 years of data from Aspvreten, Sweden

Abstract. Size-resolved aerosol trends were investigated based on a 17-year data set (2000–2017) from the rural background site Aspvreten located in southern Sweden (58.8∘ N, 17.4∘ E). Cluster analysis of the size distributions was performed to aid in the interpretation of the data. The results confirm previous findings of decreasing aerosol mass and number during the last decades as a result of reduced anthropogenic emissions in Europe. We show that both particle modal number concentration and size have substantially been reduced during the last 17 years. Negative trends in particle number concentration of about 10 cm−3 yr−1 are present for nuclei, Aitken, and accumulation modes. In total, integral particle number concentration has decreased by 30 %, from 1860 to ca. 1300 cm−3. The reduction in modal number concentration is accompanied by a decrease in modal size, and this decrease is largest for the accumulation mode (2 nm yr−1 or about 17 % for the whole period). These reductions have resulted in a decrease in submicron particle mass (< 390 nm) by more than 50 % over the period 2000–2017. These decreases are similar to observations found at other stations in northern Europe. Although all size classes show a downward trend as annual averages, we also show that observed trends are not evenly distributed over the year and that a rather complex picture emerges where both sign and magnitude of trends vary with season and size. The strongest negative trends are present during spring (accumulation mode) and autumn (Aitken mode). The strongest positive trends are present during summer months (Aitken mode). The combined trajectory and data analyses do not present evidence for an increase in new particle formation formed locally, although some evidence of increased new particle formation some distance away from the receptor is present. Observed aerosol size distribution data, together with an adiabatic cloud parcel model, were further used to estimate the change in cloud droplet concentration for various assumptions of updraught velocities and aerosol chemical composition. The results indicate a substantial increase in the atmospheric brightening effect due to a reduction in cloud reflectivity corresponding to 10 %–12 % reduction in cloud albedo over the period 2000–2017.

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On the seasonal variation of observed size distributions in Northern Europe and their changes with decreasing anthropogenic emissions in Europe: climatology and trend analysis based on 17 years data from Aspvreten, Sweden

10.5194/acp-2019-332 ◽

2019 ◽

Author(s):

Peter Tunved ◽

Johan Ström

Keyword(s):

Particle Number ◽

Number Concentration ◽

Northern Europe ◽

Anthropogenic Emissions ◽

Particle Number Concentration ◽

Size Distributions ◽

Modal Number ◽

Data Set ◽

Aerosol Mass ◽

Total Integral

Abstract. Size resolved aerosol trends were investigate based on a 17-year data set (2000–2017) from the rural background site Aspvreten located in southern Sweden (58.8° N, 17.4° E). Cluster analysis of the size distributions was performed to aid in the interpretation of the data. The results confirm previous findings of decreasing aerosol mass during last decades as a result of reduced anthropogenic emissions in Europe. We show that both particle modal number concentration and size substantially has been reduced during last decades. Negative trends in particle number concentration of about 10 cm−3 y−1 is present for nuclei, Aitken and accumulation modes. In total, integral particle number concentration has decreased by 30 %, from 1860 cm−3 to ca 1300 cm−3. This decrease is similar to observations found at other stations in Northern Europe. The reduction in modal number concentration is accompanied by a decrease in modal size, and this decrease is largest for the accumulation mode (2 nm y−1 or about 17 % for the whole period). These reductions have resulted in a decrease in submicron particle mass (

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Particle number concentrations over Europe in 2030: the role of emissions and new particle formation

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-10271-2013 ◽

2013 ◽

Vol 13 (20) ◽

pp. 10271-10283 ◽

Cited By ~ 7

Author(s):

L. Ahlm ◽

J. Julin ◽

C. Fountoukis ◽

S. N. Pandis ◽

I. Riipinen

Keyword(s):

Human Health ◽

Particle Number ◽

Aerosol Particles ◽

Particle Formation ◽

Number Concentration ◽

Anthropogenic Emissions ◽

Particle Number Concentration ◽

New Particle Formation ◽

So2 Emissions ◽

Emission Reductions

Abstract. The aerosol particle number concentration is a key parameter when estimating impacts of aerosol particles on climate and human health. We use a three-dimensional chemical transport model with detailed microphysics, PMCAMx-UF, to simulate particle number concentrations over Europe in the year 2030, by applying emission scenarios for trace gases and primary aerosols. The scenarios are based on expected changes in anthropogenic emissions of sulfur dioxide, ammonia, nitrogen oxides, and primary aerosol particles with a diameter less than 2.5 μm (PM2.5) focusing on a photochemically active period, and the implications for other seasons are discussed. For the baseline scenario, which represents a best estimate of the evolution of anthropogenic emissions in Europe, PMCAMx-UF predicts that the total particle number concentration (Ntot) will decrease by 30–70% between 2008 and 2030. The number concentration of particles larger than 100 nm (N100), a proxy for cloud condensation nuclei (CCN) concentration, is predicted to decrease by 40–70% during the same period. The predicted decrease in Ntot is mainly a result of reduced new particle formation due to the expected reduction in SO2 emissions, whereas the predicted decrease in N100 is a result of both decreasing condensational growth and reduced primary aerosol emissions. For larger emission reductions, PMCAMx-UF predicts reductions of 60–80% in both Ntot and N100 over Europe. Sensitivity tests reveal that a reduction in SO2 emissions is far more efficient than any other emission reduction investigated, in reducing Ntot. For N100, emission reductions of both SO2 and PM2.5 contribute significantly to the reduced concentration, even though SO2 plays the dominant role once more. The impact of SO2 for both new particle formation and growth over Europe may be expected to be somewhat higher during the simulated period with high photochemical activity than during times of the year with less incoming solar radiation. The predicted reductions in both Ntot and N100 between 2008 and 2030 in this study will likely reduce both the aerosol direct and indirect effects, and limit the damaging effects of aerosol particles on human health in Europe.

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Variation of size-segregated particle number concentrations in wintertime Beijing

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-1201-2020 ◽

2020 ◽

Vol 20 (2) ◽

pp. 1201-1216 ◽

Cited By ~ 10

Author(s):

Ying Zhou ◽

Lubna Dada ◽

Yiliang Liu ◽

Yueyun Fu ◽

Juha Kangasluoma ◽

...

Keyword(s):

Particle Number ◽

Particle Formation ◽

Number Concentration ◽

Spatial And Temporal Variability ◽

Particle Number Concentration ◽

New Particle Formation ◽

Accumulation Mode ◽

Nucleation Mode ◽

Secondary Sources ◽

Haze Days

Abstract. The spatial and temporal variability of the number size distribution of aerosol particles is an indicator of the dynamic behavior of Beijing's atmospheric pollution cocktail. This variation reflects the strength of different primary and secondary sources, such as traffic and new particle formation, as well as the main processes affecting the particle population. In this paper, we report size-segregated particle number concentrations observed at a newly developed Beijing station during the winter of 2018. Our measurements covered particle number size distributions over the diameter range of 1.5 nm–1 µm (cluster mode, nucleation mode, Aitken mode and accumulation mode), thus being descriptive of a major fraction of the processes taking place in the atmosphere of Beijing. Here we focus on explaining the concentration variations in the observed particle modes, by relating them to the potential aerosol sources and sinks, and on understanding the connections between these modes. We considered haze days and new particle formation event days separately. Our results show that during the new particle formation (NPF) event days increases in cluster mode particle number concentration were observed, whereas during the haze days high concentrations of accumulation mode particles were present. There was a tight connection between the cluster mode and nucleation mode on both NPF event and haze days. In addition, we correlated the particle number concentrations in different modes with concentrations of trace gases and other parameters measured at our station. Our results show that the particle number concentration in all the modes correlated with NOx, which reflects the contribution of traffic to the whole submicron size range. We also estimated the contribution of ion-induced nucleation in Beijing, and we found this contribution to be negligible.

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Urban aerosol number size distributions

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-3-5139-2003 ◽

2003 ◽

Vol 3 (5) ◽

pp. 5139-5184 ◽

Cited By ~ 4

Author(s):

T. Hussein ◽

A. Puustinen ◽

P. P. Aalto ◽

J. M. Mäkelä ◽

K. Hämeri ◽

...

Keyword(s):

Particle Number ◽

Number Concentration ◽

Building Construction ◽

Traffic Density ◽

Urban Aerosol ◽

Size Distributions ◽

Accumulation Mode ◽

Total Particle Number ◽

Total Particle ◽

Aitken Mode

Abstract. Aerosol number size distributions were measured continuously in Helsinki, Finland from 5 May 1997 to 28 February 2003. The daily, monthly and annual patterns were investigated. The temporal variation of the particle number concentration was seen to follow the traffic density. The highest total particle number concentrations were usually observed during workdays; especially on Fridays, and the lower concentrations occurred during weekends; especially Sundays. Seasonally, the highest total number concentrations were usually observed during winter and spring and the lowest during June and July. More than 80\\% of the particle number size distributions were tri-modal: nucleation mode (Dp < 30 nm), Aitken mode (20–100 nm) and accumulation mode (Dp > 90 nm). Less than 20% of the particle number size distributions have either two modes or consisted of more than three modes. Two different measurement sites are used; in the first place (Siltavuori, 5 May 1997–5 March 2001), the overall means of the integrated particle number concentrations were 7100 cm−3, 6320 cm−3, and 960 cm−3, respectively, for nucleation, Aitken, and accumulation modes. In the second site (Kumpula, 6 March 2001–28 February 2003) they were 5670 cm−3, 4050 cm−3, and 900 cm−3. The total number concentration in nucleation and Aitken modes were usually significantly higher during weekdays than during weekends. The variations in accumulation mode were less pronounced. The smaller concentrations in Kumpula were mainly due to building construction and also slight overall decreasing trend during these years. During the site changing a period of simultaneous measurements over two weeks were performed showing nice correlation in both sites.

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Particle number concentrations over Europe in 2030: the role of emissions and new particle formation

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-8769-2013 ◽

2013 ◽

Vol 13 (4) ◽

pp. 8769-8803

Author(s):

L. Ahlm ◽

J. Julin ◽

C. Fountoukis ◽

S. N. Pandis ◽

I. Riipinen

Keyword(s):

Human Health ◽

Particle Number ◽

Aerosol Particles ◽

Particle Formation ◽

Number Concentration ◽

Anthropogenic Emissions ◽

Particle Number Concentration ◽

New Particle Formation ◽

So2 Emissions ◽

Emission Reductions

Abstract. The aerosol particle number concentration is a key parameter when estimating impacts of aerosol particles on climate and human health. We use a three-dimensional chemical transport model with detailed microphysics, PMCAMx-UF, to simulate particle number concentrations over Europe in the year 2030, by applying emission scenarios for trace gases and primary aerosols. The scenarios are based on expected changes in anthropogenic emissions of sulphur dioxide, ammonia, nitrogen oxides, and primary aerosol particles with a diameter less than 2.5 μm (PM2.5) focusing on a photochemically active period. For the baseline scenario, which represents a best estimate of the evolution of anthropogenic emissions in Europe, PMCAMx-UF predicts that the total particle number concentration (Ntot) will decrease by 30–70% between 2008 and 2030. The number concentration of particles larger than 100 nm (N100), a proxy for cloud condensation nuclei (CCN) concentration, is predicted to decrease by 40–70% during the same period. The predicted decrease in Ntot is mainly a result of reduced new particle formation due to the expected reduction in SO2 emissions, whereas the predicted decrease in N100 is a result of both decreasing condensational growth and reduced primary aerosol emissions. For larger emission reductions, PMCAMx-UF predicts reductions of 60–80% in both Ntot and N100 over Europe. Sensitivity tests reveal that a reduction in SO2 emissions is far more efficient than any other emission reduction investigated, in reducing Ntot. For N100, emission reductions of both SO2 and PM2.5 contribute significantly to the reduced concentration, even though SO2 plays the dominant role once more. The impact of SO2 for both new particle formation and growth over Europe may be expected to be somewhat higher during the simulated period with high photochemical activity than during times of the year with less incoming solar radiation. The predicted reductions in both Ntot and N100 between 2008 and 2030 in this study will likely reduce both the aerosol direct and indirect effects, and limit the damaging effects of aerosol particles on human health in Europe.

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Impact of Urban Pollution on Organic-Mediated New-Particle Formation and Particle Number Concentration in the Amazon Rainforest

Environmental Science & Technology ◽

10.1021/acs.est.0c07465 ◽

2021 ◽

Vol 55 (8) ◽

pp. 4357-4367

Author(s):

Bin Zhao ◽

Jerome D. Fast ◽

Neil M. Donahue ◽

Manish Shrivastava ◽

Meredith Schervish ◽

...

Keyword(s):

Particle Number ◽

Urban Pollution ◽

Particle Formation ◽

Number Concentration ◽

Amazon Rainforest ◽

Particle Number Concentration ◽

New Particle Formation

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Modeling particle nucleation and growth over northern California during the 2010 CARES campaign

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-12283-2015 ◽

2015 ◽

Vol 15 (21) ◽

pp. 12283-12313 ◽

Cited By ~ 11

Author(s):

A. Lupascu ◽

R. Easter ◽

R. Zaveri ◽

M. Shrivastava ◽

M. Pekour ◽

...

Keyword(s):

Size Distribution ◽

Particle Number ◽

Particle Formation ◽

Number Concentration ◽

Aerosol Size Distribution ◽

Particle Nucleation ◽

Particle Number Concentration ◽

New Particle Formation ◽

Organic Vapors ◽

Diurnal Variability

Abstract. Accurate representation of the aerosol lifecycle requires adequate modeling of the particle number concentration and size distribution in addition to their mass, which is often the focus of aerosol modeling studies. This paper compares particle number concentrations and size distributions as predicted by three empirical nucleation parameterizations in the Weather Research and Forecast coupled with chemistry (WRF-Chem) regional model using 20 discrete size bins ranging from 1 nm to 10 μm. Two of the parameterizations are based on H2SO4, while one is based on both H2SO4 and organic vapors. Budget diagnostic terms for transport, dry deposition, emissions, condensational growth, nucleation, and coagulation of aerosol particles have been added to the model and are used to analyze the differences in how the new particle formation parameterizations influence the evolving aerosol size distribution. The simulations are evaluated using measurements collected at surface sites and from a research aircraft during the Carbonaceous Aerosol and Radiative Effects Study (CARES) conducted in the vicinity of Sacramento, California. While all three parameterizations captured the temporal variation of the size distribution during observed nucleation events as well as the spatial variability in aerosol number, all overestimated by up to a factor of 2.5 the total particle number concentration for particle diameters greater than 10 nm. Using the budget diagnostic terms, we demonstrate that the combined H2SO4 and low-volatility organic vapor parameterization leads to a different diurnal variability of new particle formation and growth to larger sizes compared to the parameterizations based on only H2SO4. At the CARES urban ground site, peak nucleation rates are predicted to occur around 12:00 Pacific (local) standard time (PST) for the H2SO4 parameterizations, whereas the highest rates were predicted at 08:00 and 16:00 PST when low-volatility organic gases are included in the parameterization. This can be explained by higher anthropogenic emissions of organic vapors at these times as well as lower boundary-layer heights that reduce vertical mixing. The higher nucleation rates in the H2SO4-organic parameterization at these times were largely offset by losses due to coagulation. Despite the different budget terms for ultrafine particles, the 10–40 nm diameter particle number concentrations from all three parameterizations increased from 10:00 to 14:00 PST and then decreased later in the afternoon, consistent with changes in the observed size and number distribution. We found that newly formed particles could explain up to 20–30 % of predicted cloud condensation nuclei at 0.5 % supersaturation, depending on location and the specific nucleation parameterization. A sensitivity simulation using 12 discrete size bins ranging from 1 nm to 10 μm diameter gave a reasonable estimate of particle number and size distribution compared to the 20 size bin simulation, while reducing the associated computational cost by ~ 36 %.

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Urban aerosol size distributions over the Mediterranean city of Barcelona, NE Spain

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-16457-2012 ◽

2012 ◽

Vol 12 (7) ◽

pp. 16457-16492 ◽

Cited By ~ 3

Author(s):

M. Dall'Osto ◽

D.C.S. Beddows ◽

J. Pey ◽

S. Rodriguez ◽

A. Alastuey ◽

...

Keyword(s):

Particle Number ◽

Number Concentration ◽

Aerosol Size Distribution ◽

Time Variability ◽

Small Contribution ◽

Particle Number Concentration ◽

Size Distributions ◽

Total Particle Number ◽

Total Particle ◽

One Year

Abstract. Differential mobility particle sizer (DMPS) aerosol concentrations (N13–800) were collected over a one-year-period (2004) at an urban background site in Barcelona, North-Eastern Spain. Quantitative contributions to particle number concentrations of the nucleation (33–38%), Aitken (39–49%) and accumulation mode (18–22%) were estimated. We examined the source and time variability of atmospheric aerosol particles by using both K-means clustering and Positive Matrix Factorization (PMF) analysis. Performing clustering analysis on hourly size distributions, nine K-means DMPS clusters were identified and, by directional association, diurnal variation and relationship to meteorological and pollution variables, four typical aerosol size distribution scenarios were identified: traffic (69% of the time), dilution (15% of the time), summer background conditions (4% of the time) and regional pollution (12% of the time). According to the results of PMF, vehicle exhausts are estimated to contribute at least to 62–66% of the total particle number concentration, with a slightly higher proportion distributed towards the nucleation mode (34%) relative to the Aitken mode (28–32%). Photochemically induced nucleation particles make only a small contribution to the total particle number concentration (2–3% of the total), although only particles larger than 13 nm were considered in this study. Overall the combination of the two statistical methods is successful at separating components and quantifying relative contributions to the particle number population.

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CCN production by new particle formation in the free troposphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-1529-2017 ◽

2017 ◽

Vol 17 (2) ◽

pp. 1529-1541 ◽

Cited By ~ 17

Author(s):

Clémence Rose ◽

Karine Sellegri ◽

Isabel Moreno ◽

Fernando Velarde ◽

Michel Ramonet ◽

...

Keyword(s):

Particle Number ◽

Particle Growth ◽

Particle Formation ◽

Number Concentration ◽

Particle Number Concentration ◽

Free Troposphere ◽

New Particle Formation ◽

Data Set ◽

Radiative Processes ◽

The Impact

Abstract. Global models predict that new particle formation (NPF) is, in some environments, responsible for a substantial fraction of the total atmospheric particle number concentration and subsequently contributes significantly to cloud condensation nuclei (CCN) concentrations. NPF events were frequently observed at the highest atmospheric observatory in the world, on Chacaltaya (5240 m a.s.l.), Bolivia. The present study focuses on the impact of NPF on CCN population. Neutral cluster and Air Ion Spectrometer and mobility particle size spectrometer measurements were simultaneously used to follow the growth of particles from cluster sizes down to ∼ 2 nm up to CCN threshold sizes set to 50, 80 and 100 nm. Using measurements performed between 1 January and 31 December 2012, we found that 61 % of the 94 analysed events showed a clear particle growth and significant enhancement of the CCN-relevant particle number concentration. We evaluated the contribution of NPF, relative to the transport and growth of pre-existing particles, to CCN size. The averaged production of 50 nm particles during those events was 5072, and 1481 cm−3 for 100 nm particles, with a larger contribution of NPF compared to transport, especially during the wet season. The data set was further segregated into boundary layer (BL) and free troposphere (FT) conditions at the site. The NPF frequency of occurrence was higher in the BL (48 %) compared to the FT (39 %). Particle condensational growth was more frequently observed for events initiated in the FT, but on average faster for those initiated in the BL, when the amount of condensable species was most probably larger. As a result, the potential to form new CCN was higher for events initiated in the BL (67 % against 53 % in the FT). In contrast, higher CCN number concentration increases were found when the NPF process initially occurred in the FT, under less polluted conditions. This work highlights the competition between particle growth and the removal of freshly nucleated particles by coagulation processes. The results support model predictions which suggest that NPF is an effective source of CCN in some environments, and thus may influence regional climate through cloud-related radiative processes.

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New Particle Formation and impact on CCN concentrations in the boundary layer and free troposphere at the high altitude station of Chacaltaya (5240 m a.s.l.), Bolivia

10.5194/acp-2016-696 ◽

2016 ◽

Author(s):

C. Rose ◽

K. Sellegri ◽

I. Moreno ◽

F. Velarde ◽

M. Ramonet ◽

...

Keyword(s):

Boundary Layer ◽

Particle Number ◽

Particle Growth ◽

Particle Formation ◽

Number Concentration ◽

Particle Number Concentration ◽

Free Troposphere ◽

New Particle Formation ◽

Radiative Processes ◽

The Impact

Abstract. Global models predict that new particle formation (NPF) is, in some environments, responsible for a substantial fraction of the total atmospheric particle number concentration and subsequently contribute significantly to cloud condensation nuclei (CCN) concentrations. NPF events were frequently observed at the highest atmospheric observatory in the world, Chacaltaya (5240 m a.s.l.), Bolivia. The present study focuses on the impact of NPF on CCN population. Neutral cluster and Air Ion Spectrometer and mobility particle size spectrometer measurements were simultaneously used to follow the growth of particles from cluster sizes down to ~ 2 nm up to CCN threshold sizes set to 50, 80 and 100 nm. Using measurements performed between January 1 and December 31 2012, we found that 61% of the 94 analysed events showed a clear particle growth and significant enhancement of the CCN-relevant particle number concentration. We evaluated the contribution of NPF events relative to the transport of pre-existing particles to the site. The averaged production of 50 nm particles during those events was 5072 cm−3, and 1481 cm−3 for 100 nm particles, with a larger contribution of NPF compared to transport, especially during the wet season. The data set was further segregated into boundary layer (BL) and free troposphere (FT) conditions at the site. The NPF frequency of occurrence was higher in the BL (48 %) compared to the FT (39 %). Particle condensational growth was more frequently observed for events initiated in the FT, but on average faster for those initiated in the BL, when the amount of condensable species was most probably larger. As a result, the potential to form new CCN was higher for events initiated in the BL (67 % against 56 % in the FT). In contrast, higher CCN number concentration increases were found when the NPF process initially occurred in the FT, under less polluted conditions. This work highlights the competition between particle growth and the removal of freshly nucleated particles by coagulation processes. The results support model predictions which suggest that NPF is an effective source of CCN in some environments, and thus may influence regional climate through cloud related radiative processes.

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