scholarly journals Long term particle size distribution measurements at Mount Waliguan, a high-altitude site in inland China

2009 ◽  
Vol 9 (1) ◽  
pp. 2049-2079
Author(s):  
N. Kivekäs ◽  
J. Sun ◽  
M. Zhan ◽  
V.-M. Kerminen ◽  
A. Hyvärinen ◽  
...  
Keyword(s):  
Particle Concentration ◽  
Particle Number ◽  
Anthropogenic Pollution ◽  
Number Concentration ◽  
Average Particle ◽  
Ambient Conditions ◽  
Night Time ◽  
Air Masses ◽  
Nucleation Mode ◽  
Aitken Mode

Abstract. Particle number size distributions in size range 12–570nm were measured continuously at Mount Waliguan, a remote mountain-top station in inland China. The station is located at the altitude of 3816 m above the sea level, and some 600 m above the surrounding area. The measurement period lasted from September 2005 to May 2007. The measurements were verified with independent CPC measurements at the same site. The average particle concentration in ambient conditions was 2040 cm−3, which is higher than the values measured at similar altitude in other regions of the world. On average, the Aitken mode contributed to roughly half of the particle number concentration. The concentrations were found to be higher during the summer than during the winter. The diurnal variation was also investigated and a clear pattern was found for the nucleation mode during all seasons, so that the nucleation mode particle concentration increased in the afternoon. The same pattern was visible in the Aitken mode during the summer, whereas the accumulation mode did not show any level of diurnal pattern. Excluding the nucleation mode, the average day-time particle concentrations were not significantly higher than those measured at night-time, indicating no systematic pattern of change between planetary boundary layer conditions and free troposphere conditions. In air masses coming from east, the number concentration of particles was higher than in other air masses, which indicates that the air mass might be affected by anthropogenic pollution east of the station. Also other factors, such as active new-particle formation, keep aerosol number concentrations high in the area.

scholarly journals Long term particle size distribution measurements at Mount Waliguan, a high-altitude site in inland China

2009 ◽  
Vol 9 (15) ◽  
pp. 5461-5474 ◽  
Author(s):  
N. Kivekäs ◽  
J. Sun ◽  
M. Zhan ◽  
V.-M. Kerminen ◽  
A. Hyvärinen ◽  
...  
Keyword(s):  
Particle Concentration ◽  
Particle Number ◽  
Anthropogenic Pollution ◽  
Number Concentration ◽  
Average Particle ◽  
Ambient Conditions ◽  
Night Time ◽  
Air Masses ◽  
Nucleation Mode ◽  
Aitken Mode

Abstract. Particle number size distributions in size range 12–570 nm were measured continuously at Mount Waliguan, a remote mountain-top station in inland China. The station is located at the altitude of 3816 m a.s.l., and some 600–1200 m above the surrounding area. The measurement period lasted from September 2005 to May 2007. The measurements were verified with independent CPC measurements at the same site. The average particle concentration in ambient conditions was 2030 cm−3, which is higher than the values measured at similar altitude in other regions of the world. On average, the Aitken mode contributed to roughly half of the particle number concentration. The concentrations were found to be higher during the summer than during the winter. The diurnal variation was also investigated and a clear pattern was found for the nucleation mode during all seasons, so that the nucleation mode particle concentration increased in the afternoon. The same pattern was visible in the Aitken mode during the summer, whereas the accumulation mode did not show any level of diurnal pattern during any season. Excluding the nucleation mode, the average day-time particle concentrations were not significantly higher than those measured at night-time, indicating no systematic pattern of change between planetary boundary layer conditions and free troposphere conditions. In air masses coming from east, the number concentration of particles was higher than in other air masses, which indicates that the air mass might be affected anthropogenic pollution east of the station. Also other factors, such as active new-particle formation, keep aerosol number concentrations high in the area.

scholarly journals First long-term study of particle number size distributions and new particle formation events of regional aerosol in the North China Plain

2011 ◽  
Vol 11 (4) ◽  
pp. 1565-1580 ◽  
Author(s):  
X. J. Shen ◽  
J. Y. Sun ◽  
Y. M. Zhang ◽  
B. Wehner ◽  
A. Nowak ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Particle Number ◽  
Particle Formation ◽  
Mean Value ◽  
Number Concentration ◽  
New Particle Formation ◽  
Air Masses ◽  
Nucleation Mode ◽  
The North

Abstract. Atmospheric particle number size distributions (size range 0.003–10 μm) were measured between March 2008 and August 2009 at Shangdianzi (SDZ), a rural research station in the North China Plain. These measurements were made in an attempt to better characterize the tropospheric background aerosol in Northern China. The mean particle number concentrations of the total particle, as well as the nucleation, Aitken, accumulation and coarse mode were determined to be 1.2 ± 0.9 × 104, 3.6 ± 7.9 × 103, 4.4 ± 3.4 × 103, 3.5 ± 2.8 × 103 and 2 ± 3 cm−3, respectively. A general finding was that the particle number concentration was higher during spring compared to the other seasons. The air mass origin had an important effect on the particle number concentration and new particle formation events. Air masses from northwest (i.e. inner Asia) favored the new particle formation events, while air masses from southeast showed the highest particle mass concentration. Significant diurnal variations in particle number were observed, which could be linked to new particle formation events, i.e. gas-to-particle conversion. During particle formation events, the number concentration of the nucleation mode rose up to maximum value of 104 cm−3. New particle formation events were observed on 36% of the effective measurement days. The formation rate ranged from 0.7 to 72.7 cm−3 s−1, with a mean value of 8.0 cm−3 s−1. The value of the nucleation mode growth rate was in the range of 0.3–14.5 nm h−1, with a mean value of 4.3 nm h−1. It was an essential observation that on many occasions the nucleation mode was able to grow into the size of cloud condensation nuclei (CCN) within a matter of several hours. Furthermore, the new particle formation was regularly followed by a measurable increase in particle mass concentration and extinction coefficient, indicative of a high abundance of condensable vapors in the atmosphere under study.

scholarly journals Explicit Simulation of Aerosol Physics in a Cloud-Resolving Model: Aerosol Transport and Processing in the Free Troposphere

2006 ◽  
Vol 63 (2) ◽  
pp. 682-696 ◽  
Author(s):  
Annica M. L. Ekman ◽  
Chien Wang ◽  
Johan Ström ◽  
Radovan Krejci
Keyword(s):  
Convective Cloud ◽  
Number Concentration ◽  
Box Model ◽  
Sulfate Aerosols ◽  
Accumulation Mode ◽  
Nucleation Mode ◽  
Cloud Resolving Model ◽  
Aerosol Module ◽  
Carbon Aerosols ◽  
Aitken Mode

Abstract Large concentrations of small aerosols have been previously observed in the vicinity of anvils of convective clouds. A 3D cloud-resolving model (CRM) including an explicit size-resolving aerosol module has been used to examine the origin of these aerosols. Five different types of aerosols are considered: nucleation mode sulfate aerosols (here defined by 0 ≤ d ≤5.84 nm), Aitken mode sulfate aerosols (here defined by 5.84 nm ≤ d ≤ 31.0 nm), accumulation mode sulfate aerosols (here defined by d ≥ 31.0 nm), mixed aerosols, and black carbon aerosols. The model results suggest that approximately 10% of the initial boundary layer number concentration of Aitken mode aerosols and black carbon aerosols are present at the top of the convective cloud as the cloud reaches its decaying state. The simulated average number concentration of Aitken mode aerosols in the cloud anvil (∼1.6 × 104 cm−3) is in the same order of magnitude as observations. Thus, the model results strongly suggest that vertical convective transport, particularly during the active period of the convection, is responsible for a major part of the appearance of high concentrations of small aerosols (corresponding to the Aitken mode in the model) observed in the vicinity of cloud anvils. There is some formation of new aerosols within the cloud, but the formation is small. Nucleation mode aerosols are also efficiently scavenged through impaction scavenging by precipitation. Accumulation mode and mixed mode aerosols are efficiently scavenged through nucleation scavenging and their concentrations in the cloud anvil are either very low (mixed mode) or practically zero (accumulation mode). In addition to the 3D CRM, a box model, including important features of the aerosol module of the 3D model, has been used to study the formation of new aerosols after the cloud has evaporated. The possibility of these aerosols to grow to suitable cloud condensation or ice nuclei size is also examined. Concentrations of nucleation mode aerosols up to 3 × 104 cm−3 are obtained. The box model simulations thus suggest that new particle formation is a substantial source of small aerosols in the upper troposphere during and after the dissipation of the convective cloud. Nucleation mode and Aitken mode aerosols grow due to coagulation and condensation of H2SO4 on the aerosols, but the growth rate is low. Provided that there is enough OH available to oxidize SO2, parts of the aerosol population (∼400 cm−3) can reach the accumulation mode size bin of the box model after 46 h of simulation.

scholarly journals A statistical analysis of North East Atlantic (submicron) aerosol size distributions

2011 ◽  
Vol 11 (8) ◽  
pp. 21677-21711 ◽  
Author(s):  
M. Dall'Osto ◽  
C. Monahan ◽  
R. Greaney ◽  
D. C. S. Beddows ◽  
R. M. Harrison ◽  
...  
Keyword(s):  
Number Concentration ◽  
Open Ocean ◽  
Research Station ◽  
Marine Biota ◽  
Size Distributions ◽  
East Atlantic ◽  
Air Masses ◽  
North East ◽  
Data Coverage ◽  
Aitken Mode

Abstract. The Global Atmospheric Watch research station at Mace Head (Ireland) offers the possibility to sample some of the cleanest air masses being imported into Europe as well as some of the most polluted being exported out of Europe. We present a statistical Cluster~analysis of the physical characteristics of aerosol size distributions in air ranging from the cleanest to the most polluted for the year 2008. Data coverage achieved was 75 % throughout the year. By applying the Hartigan-Wong k-Means method, 12 Clusters were identified as systematically occurring and these 12 Clusters could be further combined into 4 categories with similar characteristics, namely: coastal nucleation category (occurring 21.3 % of the time), open ocean nucleation category (occurring 32.6 % of the time), background clean marine category (occurring 26.1 % of the time) and anthropogenic category (occurring 20 % of the time) aerosol size distributions. The coastal nucleation category is characterised by a clear and dominant nucleation mode at sizes less that 10 nm while the open ocean nucleation category is characterised by a dominant Aitken mode between 15 nm and 50 nm. The background clean marine characteristic is a clear bimodality in the size distribution, although it should be noted that either the Aitken mode or the Accumulation mode may dominate the number concentration. By contrast, the continentally-influenced size distributions are generally more mono-modal, albeit with traces of bi-modality. The open ocean category occurs more often during May, June and July, corresponding with the N. E. Atlantic high biological period. Combined with the relatively high percentage frequency of occurrence (32.6 %), this suggests that the marine biota is an important source of new aerosol particles in N. E. Atlantic Air.

scholarly journals 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

2019 ◽  
Vol 19 (23) ◽  
pp. 14849-14873 ◽  
Author(s):  
Peter Tunved ◽  
Johan Ström
Keyword(s):  
Particle Number ◽  
Particle Formation ◽  
Number Concentration ◽  
Northern Europe ◽  
Anthropogenic Emissions ◽  
Particle Number Concentration ◽  
Size Distributions ◽  
Modal Number ◽  
Accumulation Mode ◽  
Aitken Mode

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.

scholarly journals Seasonal variations of aerosol size distributions based on long-term measurements at the high altitude Himalayan site of Nepal Climate Observatory-Pyramid (5079 m), Nepal

2010 ◽  
Vol 10 (21) ◽  
pp. 10679-10690 ◽  
Author(s):  
K. Sellegri ◽  
P. Laj ◽  
H. Venzac ◽  
J. Boulon ◽  
D. Picard ◽  
...  
Keyword(s):  
Seasonal Variability ◽  
Monsoon Season ◽  
Number Concentration ◽  
Residual Layer ◽  
Research Station ◽  
Free Troposphere ◽  
Night Time ◽  
High Accumulation ◽  
Air Masses ◽  
Post Monsoon

Abstract. The present paper investigates the diurnal and seasonal variability of the aerosol total number concentration, number and volume size distribution between 10 nm and 10 μm, from a combination of a scanning mobility particle sizer (SMPS) and an optical counter (OPC), performed over a two-year period (January 2006–February 2008) at the Nepal Climate Observatory-Pyramid (NCO-P) research station, (5079 m a.s.l.). The annual average number concentration measured over the two-year period at the NCO-P is 860 cm−3. Total concentrations show a strong seasonality with maxima during pre-monsoon and post-monsoon seasons and minima during the dry and monsoon seasons. A diurnal variation is also clearly observed, with maxima between 09:00 and 12:00 UTC. The aerosol concentration maxima are mainly due to nucleation processes during the post-monsoon season, as witnessed by high nucleation mode integrated number concentrations, and to transport of high levels of pollution from the plains by valley breezes during the pre-monsoon season, as demonstrated by high accumulation mode integrated number concentrations. Night-time number concentration of particles (from 03:00 to 08:00 NST) are relatively low throughout the year (from 450 cm−3 during the monsoon season to 675 cm−3 during the pre-monsoon season), indicating the of high altitudes background level, as a result of downslope winds during this part of the day. However, it was found that these background concentrations are strongly influenced by the daytime concentrations, as they show the same seasonal variability. If nighttime concentrations were presumed to be representative of free troposphere (FT)/residual layer concentrations, they would be found to be two times higher than at other lower altitudes European sites, such as the Jungfraujoch. However, BL intrusions might contaminate the free troposphere/residual layer even at this altitude, especially during regional air masses influence. Night-time measurements were subsequently selected to study the FT composition according to different air masses, and the effect of long range transport to the station.

scholarly journals Evolution under dark conditions of particles from old and modern diesel vehicles in a new environmental chamber characterized with fresh exhaust emissions

2021 ◽  
Vol 14 (12) ◽  
pp. 7627-7655
Author(s):  
Boris Vansevenant ◽  
Cédric Louis ◽  
Corinne Ferronato ◽  
Ludovic Fine ◽  
Patrick Tassel ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Particle Number ◽  
Particle Surface ◽  
Number Concentration ◽  
Photochemical Reactions ◽  
Particle Mass ◽  
Particle Number Concentration ◽  
Physical Processes ◽  
Nucleation Mode ◽  
Wall Losses

Abstract. Atmospheric particles have several impacts on health and the environment, especially in urban areas. Parts of those particles are not fresh and have undergone atmospheric chemical and physical processes. Due to a lack of representativeness of experimental conditions and experimental artifacts such as particle wall losses in chambers, there are uncertainties on the effects of physical processes (condensation, nucleation and coagulation) and their role in particle evolution from modern vehicles. This study develops a new method to correct wall losses, accounting for size dependence and experiment-to-experiment variations. It is applied to the evolution of fresh diesel exhaust particles to characterize the physical processes which they undergo. The correction method is based on the black carbon decay and a size-dependent coefficient to correct particle distributions. Six diesel passenger cars, Euro 3 to Euro 6, were driven on a chassis dynamometer with Artemis Urban cold start and Artemis Motorway cycles. Exhaust was injected in an 8 m3 chamber with Teflon walls. The physical evolution of particles was characterized during 6 to 10 h. Increase in particle mass is observed even without photochemical reactions due to the presence of intermediate-volatility organic compounds and semi-volatile organic compounds. These compounds were quantified at emission and induce a particle mass increase up to 17 % h−1, mainly for the older vehicles (Euro 3 and Euro 4). Condensation is 4 times faster when the available particle surface is multiplied by 6.5. If initial particle number concentration is below [8–9] × 104 cm−3, a nucleation mode seems to be present but not measured by a scanning mobility particle sizer (SMPS). The growth of nucleation-mode particles results in an increase in measured [PN]. Above this threshold, particle number concentration decreases due to coagulation, up to −27 % h−1. Under those conditions, the chamber and experimental setup are well suited to characterizing and quantifying the process of coagulation.

scholarly journals New particle formation in coastal New Zealand with a focus on open ocean air masses

2021 ◽  
Author(s):  
Maija Peltola ◽  
Clémence Rose ◽  
Jonathan V. Trueblood ◽  
Sally Gray ◽  
Mike Harvey ◽  
...  
Keyword(s):  
New Zealand ◽  
Particle Concentration ◽  
Particle Number ◽  
Particle Formation ◽  
Open Ocean ◽  
New Particle Formation ◽  
Air Masses ◽  
Wind Speeds ◽  
Marine Air ◽  
Aerosol Properties

Abstract. Even though oceans cover the majority of the Earth, most aerosol measurements are from continental sites. We measured aerosol particle number size distribution at Baring Head, in coastal New Zealand, over a total period of 10 months to study aerosol properties and new particle formation, with a special focus on aerosol formation in open ocean air masses. Particle concentrations were higher in land-influenced air compared to clean marine air in all size classes from sub-10 nm to cloud condensation nuclei sizes. When classifying the particle number size distributions with traditional methods designed for continental sites, new particle formation was observed at the station throughout the year with an average event frequency of 23 %. While most of these traditional event days had some land-influence, we also observed particle growth starting from nucleation mode during 16 % of the data in clean marine air and at least part of this growth was connected to nucleation in the marine boundary layer. Sub-10 nm particles accounted for 29 % of the total aerosol number concentration of particles larger than 1 nm in marine air during the spring. This shows that nucleation in marine air is frequent enough to influence the total particle concentration. Particle formation in land-influenced air was more intense and had on average higher growth rates than what was found for marine air. Particle formation and primary emissions increased particle number concentrations as a function of time spent over land during the first 1–2 days spent over land. After this, nucleation seems to start getting suppressed by the pre-existing particle population, but accumulation mode particle concentration keeps increasing, likely due to primary particle emissions. Further work showed that traditional NPF events were favoured by sunny conditions with low relative humidity and wind speeds. In marine air, formation of sub-10 nm particles was favoured by low temperatures, relative humidity, and wind speeds and could happen even during the night. Our future work will study the mechanisms responsible for particle formation at Baring Head with a focus on different chemical precursor species. This study sheds light on both new particle formation in open ocean air masses coming from the Southern Ocean and local aerosol properties in New Zealand.

scholarly journals Interpretation of particle number size distributions measured across an urban area during the FASTER campaign

2019 ◽  
Vol 19 (1) ◽  
pp. 39-55 ◽  
Author(s):  
Roy M. Harrison ◽  
David C. S. Beddows ◽  
Mohammed S. Alam ◽  
Ajit Singh ◽  
James Brean ◽  
...  
Keyword(s):  
Size Distribution ◽  
Black Carbon ◽  
Particle Number ◽  
Size Distributions ◽  
Night Time ◽  
The West ◽  
Number Count ◽  
Nucleation Mode ◽  
Wind Speeds ◽  
Number Counts

Abstract. Particle number size distributions have been measured simultaneously by scanning mobility particle sizers (SMPSs) at five sites in central London for a 1 month campaign in January–February 2017. These measurements were accompanied by condensation particle counters (CPCs) to measure total particle number count at four of the sites and Aethalometers measuring black carbon (BC) at five sites. The spatial distribution and inter-relationships of the particle size distribution and SMPS total number counts with CPC total number counts and black carbon measurements have been analysed in detail as well as variations in the size distributions. One site (Marylebone Road) was in a street canyon with heavy traffic, one site (Westminster University) was on a rooftop adjacent to the Marylebone Road sampler, and a further sampler was located at Regent's University within a major park to the north of Marylebone Road. A fourth sampler was located nearby at 160 m above ground level on the BT tower and a fifth sampler was located 4 km to the west of the main sampling region at North Kensington. Consistent with earlier studies it was found that the mode in the size distribution had shifted to smaller sizes at the Regent's University (park) site, the mean particle shrinkage rate being 0.04 nm s−1 with slightly lower values at low wind speeds and some larger values at higher wind speeds. There was evidence of complete evaporation of the semi-volatile nucleation mode under certain conditions at the elevated BT Tower site. While the SMPS total count and black carbon showed typical traffic-dominated diurnal profiles, the CPC count data typically peaked during night-time as did CPC∕SMPS and CPC∕BC ratios. This is thought to be due to the presence of high concentrations of small particles (2.5–15 nm diameter) probably arising from condensational growth from traffic emissions during the cooler night-time conditions. Such behaviour was most marked at the Regent's University and Westminster University sites and less so at Marylebone Road, while at the elevated BT Tower site the ratio of particle number (CPC) to black carbon peaked during the morning rush hour and not at night-time, unlike the other sites. An elevation in nucleation mode particles associated with winds from the west and WSW sector was concluded to result from emissions from London Heathrow Airport, despite a distance of 22 km from the central London sites.

scholarly journals Aerosol arriving on the Caribbean island of Barbados: Physical properties and origin

2016 ◽  
Author(s):  
Heike Wex ◽  
Katrin Dieckmann ◽  
Greg C. Roberts ◽  
Thomas Conrath ◽  
Miguel A. Izaguirre ◽  
...  
Keyword(s):  
Particle Number ◽  
Size Range ◽  
Cloud Condensation Nuclei ◽  
Dust Particles ◽  
Cloud Base ◽  
Trade Wind ◽  
Air Masses ◽  
Airborne Measurements ◽  
Sahel Region ◽  
Aitken Mode

Abstract. The marine aerosol arriving at Barbados (Ragged Point) was characterized during two three-week long measurement periods in November 2010 and April 2011, in the context of the measurement campaign CARRIBA (Cloud, Aerosol, Radiation and tuRbulence in the trade wInd regime over BArbados). By comparison between ground based and airborne measurements it was shown that the former are representative for the marine boundary layer at least up to cloud base. In general, total particle number concentrations (Ntotal) ranged from as low as 100 cm−3 up to 800 cm−3, while number concentrations for cloud condensation nuclei (NCCN) at a supersaturation of 0.26 % ranged from some ten to 600 cm−3. Ntotal and NCCN depended on the air mass origin. Three distinct types of air masses were found. One type showed elevated values for both, Ntotal and NCCN and could be attributed to long range transport from Africa, by which biomass burning particles from the Sahel region and / or mineral dust particles from the Sahara were advected. The second and third type both had values for NCCN below 200 cm−3, and a clear minimum in the particle number size distribution (NSD) around 70 to 80 nm (Hoppel minimum). While for one of these two types the accumulation mode was dominating (albeit less so than for air masses advected from Africa), the Aitken mode dominated the other and contributed more than 50 % of all particles. These Aitken mode particles likely were formed by new particle formation no more than three days prior to the measurements. Hygroscopicity of particles in the CCN size range was determined from CCN measurements to be κ = 0.66 on average, which suggests that these particles contain mainly sulfate and do not show a strong influence from organic material, at least not during the months when measurements were made. The average κ could be used to derive NCCN from measured number size distributions, showing that this is a valid approach to obtain NCCN. Although the total particulate mass sampled on filters was found to be dominated by Na+ and Cl−, this was found to be contributed by a small number of large particles (> 500 nm, mostly even in the super-micron size range), in number concentrations below 1 cm−3. Hence it can be concluded that sea-spray does not contribute noticeably to NCCN. This is further supported by finding no correlation between Ntotal and wind speed.

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