scholarly journals New particle formation events in semi-clean South African savannah

2011 ◽  
Vol 11 (7) ◽  
pp. 3333-3346 ◽  
Author(s):  
V. Vakkari ◽  
H. Laakso ◽  
M. Kulmala ◽  
A. Laaksonen ◽  
D. Mabaso ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Growth Rate ◽  
Particle Size ◽  
Sulphuric Acid ◽  
Growth Rates ◽  
Formation Rate ◽  
Particle Formation ◽  
Size Distributions ◽  
New Particle Formation ◽  
Particle Formation And Growth

Abstract. This study is based on 18 months (20 July 2006–5 February 2008) of continuous measurements of aerosol particle size distributions, air ion size distributions, trace gas concentrations and basic meteorology in a semi-clean savannah environment in Republic of South Africa. New particle formation and growth was observed on 69% of the days and bursts of non-growing ions/sub-10 nm particles on additional 14% of the days. This new particle formation frequency is the highest reported from boundary layer so far. Also the new particle formation and growth rates were among the highest reported in the literature for continental boundary layer locations; median 10 nm formation rate was 2.2 cm−3 s−1 and median 10–30 nm growth rate 8.9 nm h−1. The median 2 nm ion formation rate was 0.5 cm−3 s−1 and the median ion growth rates were 6.2, 8.0 and 8.1 nm h−1 for size ranges 1.5–3 nm, 3–7 nm and 7–20 nm, respectively. The growth rates had a clear seasonal dependency with minimum during winter and maxima in spring and late summer. The relative contribution of estimated sulphuric acid to the growth rate was decreasing with increasing particle size and could explain more than 20% of the observed growth rate only for the 1.5–3 nm size range. Also the air mass history analysis indicated the highest formation and growth rates to be associated with the area of highest VOC (Volatile Organic Compounds) emissions following from biological activity rather than the highest estimated sulphuric acid concentrations. The frequency of new particle formation, however, increased nearly monotonously with the estimated sulphuric acid reaching 100% at H2SO4 concentration of 6 · 107 cm−3, which suggests the formation and growth to be independent of each other.

scholarly journals New particle formation events in semi-clean South African savannah

2010 ◽  
Vol 10 (12) ◽  
pp. 30777-30821 ◽  
Author(s):  
V. Vakkari ◽  
H. Laakso ◽  
M. Kulmala ◽  
A. Laaksonen ◽  
D. Mabaso ◽  
...  
Keyword(s):  
Growth Rate ◽  
Sulphuric Acid ◽  
Growth Rates ◽  
Formation Rate ◽  
Particle Formation ◽  
Size Distributions ◽  
New Particle Formation ◽  
Air Mass ◽  
History Analysis ◽  
Particle Formation And Growth

Abstract. This study is based on 18 months (20 July 2006–5 February 2008) of continuous measurements of aerosol particle size distributions, air ion size distributions, trace gas concentrations and basic meteorology in a semi-clean savannah environment in Republic of South Africa. New particle formation and growth was observed on 69% of the days and bursts of non-growing ions/sub-10 nm particles on additional 14% of the days. The new particle formation and growth rates were among the highest reported in the literature for continental boundary layer locations; median 10 nm formation rate was 2.2 cm−3s−1 and median 10–30 nm growth rate 8.9 nm h−1. The median 2 nm ion formation rate was 0.5 cm−3s−1 and the median ion growth rates were 6.2, 8.0 and 8.1 nm h−1 for size ranges 1.5–3 nm, 3–7 nm and 7–20 nm, respectively. Three different approaches were used to study the origin of the formation and growth rates: seasonal variation, air mass history analysis and estimated sulphuric acid contribution to the growth. The growth rates had a clear seasonal dependency with minimum during winter and maxima in spring and late summer and the air mass history analysis indicated the highest formation and growth rates to be associated with the area of highest VOC (Volatile Organic Compounds) emissions rather than the highest estimated sulphuric acid concentrations. The relative contribution of estimated sulphuric acid to the growth rate was decreasing with increasing particle size and could explain more than 20% of the observed growth rate only for the 1.5–3 nm size range. The implication is that the sulphuric acid alone is not enough to explain the growth, but the highest growth rates seem to originate in VOC emissions following from biological activity. The frequency of new particle formation, however, increased nearly monotonously with the estimated sulphuric acid reaching 100% at H2SO4 concentration of 4×107cm−3, which suggests the formation and growth to be independent of each other.

scholarly journals The contribution of sulphuric acid to atmospheric particle formation and growth: a comparison between boundary layers in Northern and Central Europe

2005 ◽  
Vol 5 (7) ◽  
pp. 1773-1785 ◽  
Author(s):  
V. Fiedler ◽  
M. Dal Maso ◽  
M. Boy ◽  
H. Aufmhoff ◽  
J. Hoffmann ◽  
...  
Keyword(s):  
Sulphuric Acid ◽  
Central Europe ◽  
Growth Rates ◽  
Particle Number ◽  
Particle Growth ◽  
Particle Formation ◽  
Initial Growth ◽  
Size Distributions ◽  
Vapor Source ◽  
Particle Formation And Growth

Abstract. Atmospheric gaseous sulphuric acid was measured and its influence on particle formation and growth was investigated building on aerosol data. The measurements were part of the EU-project QUEST and took place at two different measurement sites in Northern and Central Europe (Hyytiälä, Finland, March-April 2003 and Heidelberg, Germany, March-April 2004). From a comprehensive data set including sulphuric acid, particle number size distributions and meteorological data, particle growth rates, particle formation rates and source rates of condensable vapors were inferred. Growth rates were determined in two different ways, from particle size distributions as well as from a so-called timeshift analysis. Moreover, correlations between sulphuric acid and particle number concentration between 3 and 6 nm were examined and the influence of air masses of different origin was investigated. Measured maximum concentrations of sulphuric acid were in the range from 1x106 to 16x106cm-3. The gaseous sulphuric acid lifetime with respect to condensation on aerosol particles ranged from 2 to 33min in Hyytiälä and from 0.5 to 8 min in Heidelberg. Most calculated values (growth rates, formation rates, vapor source rates) were considerably higher in Central Europe (Heidelberg), due to the more polluted air and higher preexistent aerosol concentrations. Close correlations between H2SO4 and nucleation mode particles (size range: 3-6 nm) were found on most days at both sites. The percentage contribution of sulphuric acid to particle growth was below 10% at both places and to initial growth below 20%. An air mass analysis indicated that at Heidelberg new particles were formed predominantly in air advected from southwesterly directions.

scholarly journals New particle formation infrequently observed in Himalayan foothills – why?

2011 ◽  
Vol 11 (4) ◽  
pp. 13193-13228 ◽  
Author(s):  
K. Neitola ◽  
E. Asmi ◽  
M. Komppula ◽  
A.-P. Hyvärinen ◽  
T. Raatikainen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Growth Rates ◽  
Secondary Particle ◽  
Particle Formation ◽  
Meteorological Conditions ◽  
New Particle Formation ◽  
Secondary Sources ◽  
Himalayan Foothills ◽  
Particle Formation And Growth ◽  
Himalayan Aerosols

Abstract. A fraction of the Himalayan aerosols originate from secondary sources, which are currently poorly quantified. To clarify the climatic importance of regional secondary particle formation at Himalayas, data from 2005 to 2010 of continuous aerosol measurements at a high-altitude (2180 m) Indian Himalayan site, Mukteshwar, were analyzed. For this period, the days were classified, and the particle formation and growth rates were calculated for clear new particle formation (NPF) event days. The NPF events showed a pronounced seasonal cycle. The frequency of the events peaked in spring, when the ratio between event and non-event days was 53 %, whereas the events were truly sporadic on any other seasons. The annual mean particle formation and growth rates were 0.40 cm−3 s−1 and 2.43 nm h−1, respectively. The clear annual cycle was found to be mainly controlled by the seasonal evolution of the Planetary Boundary Layer (PBL) height together with local meteorological conditions. Spring NPF events were connected with increased PBL height, and therefore characterised as boundary layer events, while the rare events in other seasons represented lower free tropospheric particle formation.

scholarly journals Connections between atmospheric sulphuric acid and new particle formation during QUEST III–IV campaigns in Heidelberg and Hyytiälä

2006 ◽  
Vol 6 (5) ◽  
pp. 10837-10882 ◽  
Author(s):  
I. Riipinen ◽  
S.-L. Sihto ◽  
M. Kulmala ◽  
F. Arnold ◽  
M. Dal Maso ◽  
...  
Keyword(s):  
Sulphuric Acid ◽  
Power Law ◽  
Growth Rates ◽  
Particle Production ◽  
Particle Formation ◽  
Rural Site ◽  
Main Process ◽  
Time Lags ◽  
New Particle Formation ◽  
Particle Formation And Growth

Abstract. This study investigates the connections between atmospheric sulphuric acid and new particle formation during QUEST III and BACCI/QUEST IV campaigns. The campaigns have been conducted in Heidelberg (2004) and Hyytiälä (2005), the first representing a polluted site surrounded by deciduous forest, and the second a rural site in a boreal forest environment. We have studied the role of sulphuric acid in particle formation and growth by determining 1) the power-law dependencies between sulphuric acid ([H2SO4]), and particle concentrations (N3–6) or formation rates at 1 nm and 3 nm (J1 and J3; 2) the time delays between [H2SO4] and N3–6 or J3, and the growth rates for 1–3 nm particles; 3) the empirical nucleation coefficients A and K in relations J1=A[H2SO4] and J1=K[H2SO4]2, respectively; 4) theoretical predictions for J1 and J3 for the days when no significant particle formation is observed, based on the observed sulphuric acid concentrations and condensation sinks. In both environments, N3–6 or J3 and [H2SO4] were linked via a power-law relation with exponents typically ranging from 1 to 2. The result suggests that the cluster activation theory and kinetic nucleation have the potential to explain the observed particle formation. However, some differences between the sites existed: The 1–3 nm growth rates were slightly higher and the nucleation coefficients about an order of magnitude greater in Heidelberg than in Hyytiälä conditions. The time lags between J3 and [H2SO4] were consistently lower than the corresponding delays between N3–6 and [H2SO4]. The exponents in the J3∝[H2SO4]nJ3-connection were consistently higher than or equal to the exponents in the relation N3–6∝[H2SO4]nN36. In the J1 values, no significant differences were found between the observed rates on particle formation event days and the predictions on non-event days. The J3 values predicted by the cluster activation or kinetic nucleation hypotheses, on the other hand, were considerably lower on non-event days than the rates observed on particle formation event days. This study provides clear evidence implying that the main process limiting the observable particle formation is the competition between the growth of the freshly formed particles and their loss by scavenging, rather than the initial particle production by nucleation of sulphuric acid. In general, it can be concluded that the simple models based on sulphuric acid concentrations and particle formation by cluster activation or kinetic nucleation can predict the occurence of atmospheric particle formation and growth well, if the particle scavenging is accurately accounted for.

scholarly journals Global analysis of continental boundary layer new particle formation based on long-term measurements

2018 ◽  
Author(s):  
Tuomo Nieminen ◽  
Veli-Matti Kerminen ◽  
Tuukka Petäjä ◽  
Pasi P. Aalto ◽  
Mikhail Arshinov ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Urban Areas ◽  
Global Analysis ◽  
Formation Rate ◽  
Particle Formation ◽  
Urban Environments ◽  
New Particle Formation ◽  
The World ◽  
Order Of Magnitude

Abstract. Atmospheric new particle formation (NPF) is an important phenomenon in terms of the global particle number concentrations. Here we investigated the frequency of NPF, formation rates of 10 nm particles and growth rates in the size range of 10–25 nm using at least one year of aerosol number size-distribution observations at 36 different locations around the world. The majority of these measurement sites are in the Northern Hemisphere. We found that the NPF frequency has a strong seasonal variability, taking place on about 30 % of the days in March–May and on about 10 % of the days in December–February. The median formation rate of 10 nm particles varies by about three orders of magnitude (0.01–10 cm−3 s−1) and the growth rate by about an order of magnitude (1–10 nm h−1). The smallest values of both formation and growth rates were observed at polar sites and the largest ones in urban environments or anthropogenically influenced rural sites. The correlation between the NPF event frequency and the particle formation and growth rate was at best moderate between the different measurement sites, as well as between the sites belonging to a certain environmental regime. For a better understanding of atmospheric NPF and its regional importance, we would need more observational data from different urban areas in practically all parts of the world, from additional remote and rural locations in Northern America, Asia and most of the Southern Hemisphere (especially Australia), from polar areas, and from at least a few locations over the oceans.

scholarly journals Investigation of new particle formation at the summit of Mt. Tai, China

2016 ◽  
Author(s):  
Ganglin Lv ◽  
Xiao Sui ◽  
Jianmin Chen ◽  
Rohan Jayaratne ◽  
Abdelwahid Mellouki
Keyword(s):  
Growth Rate ◽  
Sulfuric Acid ◽  
Sulfur Dioxide ◽  
Growth Rates ◽  
Formation Rate ◽  
High Elevation ◽  
Particle Formation ◽  
Mean Value ◽  
New Particle Formation ◽  
Total Particle

Abstract. To date very few field observations of new particle formation (NPF) have been carried out at the high-elevation mountain sites in China. Simultaneously measurements of particle size distributions, gas species, meteorological conditions and PM2.5 were performed at the summit of Mt. Tai (1530 m ASL) from 25 July to 24 October 2014 (І), 21 September to 9 December 2014 (И) and 16 June to 7 August 2015 (Ш). The results showed that: (i) 66 NPF events were observed during 164 days, corresponding to an occurrence frequency of 40 %. Formation rates, growth rates and condensation sinks were in the range of 1.10–57.43 cm−3 s−1, 0.58–7.76 nm h−1 and 0.40 × 10−2–6.32 × 10−2 s−1, respectively, and Mt. Tai appeared to show the larger formation rate and smaller growth rate relative to other locations in China. The mean value of sulfur dioxide on NPF days was 46 % higher than that on non-NPF days, and a higher sulfur dioxide concentration could improve the possibility of rich precursors for NPF. (ii) Sulfuric acid condensation contributed to 16.20 % of growth rate, and sulfuric acid proxy showed an obvious correlation with total particle concentration of 3–6 nm (N3–6 nm). (iii) Low PM2.5 was favourable for nucleation, and NPF days with limited higher PM2.5 seemed to have larger growth rates which might be related to particles recombination in close sizes. Four NPF events were observed on haze episodes, which could be promoted by potential specific mechanisms or pollutants. (iv) Particles formed via NPF on both clean and polluted days mainly contributed to Aiken mode eventually, and PM2.5 variation was always in accordance with particle total volume concentration.

scholarly journals Global analysis of continental boundary layer new particle formation based on long-term measurements

2018 ◽  
Vol 18 (19) ◽  
pp. 14737-14756 ◽  
Author(s):  
Tuomo Nieminen ◽  
Veli-Matti Kerminen ◽  
Tuukka Petäjä ◽  
Pasi P. Aalto ◽  
Mikhail Arshinov ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Urban Areas ◽  
Global Analysis ◽  
Formation Rate ◽  
Particle Formation ◽  
Urban Environments ◽  
New Particle Formation ◽  
The World ◽  
Order Of Magnitude

Abstract. Atmospheric new particle formation (NPF) is an important phenomenon in terms of global particle number concentrations. Here we investigated the frequency of NPF, formation rates of 10 nm particles, and growth rates in the size range of 10–25 nm using at least 1 year of aerosol number size-distribution observations at 36 different locations around the world. The majority of these measurement sites are in the Northern Hemisphere. We found that the NPF frequency has a strong seasonal variability. At the measurement sites analyzed in this study, NPF occurs most frequently in March–May (on about 30 % of the days) and least frequently in December–February (about 10 % of the days). The median formation rate of 10 nm particles varies by about 3 orders of magnitude (0.01–10 cm−3 s−1) and the growth rate by about an order of magnitude (1–10 nm h−1). The smallest values of both formation and growth rates were observed at polar sites and the largest ones in urban environments or anthropogenically influenced rural sites. The correlation between the NPF event frequency and the particle formation and growth rate was at best moderate among the different measurement sites, as well as among the sites belonging to a certain environmental regime. For a better understanding of atmospheric NPF and its regional importance, we would need more observational data from different urban areas in practically all parts of the world, from additional remote and rural locations in North America, Asia, and most of the Southern Hemisphere (especially Australia), from polar areas, and from at least a few locations over the oceans.

scholarly journals New particle formation infrequently observed in Himalayan foothills – why?

2011 ◽  
Vol 11 (16) ◽  
pp. 8447-8458 ◽  
Author(s):  
K. Neitola ◽  
E. Asmi ◽  
M. Komppula ◽  
A.-P. Hyvärinen ◽  
T. Raatikainen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Growth Rates ◽  
Secondary Particle ◽  
Particle Formation ◽  
Meteorological Conditions ◽  
New Particle Formation ◽  
Secondary Sources ◽  
Himalayan Foothills ◽  
Particle Formation And Growth ◽  
Himalayan Aerosols

Abstract. A fraction of the Himalayan aerosols originate from secondary sources, which are currently poorly quantified. To clarify the climatic importance of regional secondary particle formation in the Himalayas, data from 2005 to 2010 of continuous aerosol measurements at a high-altitude (2180 m) Indian Himalayan site, Mukteshwar, were analyzed. For this period, the days were classified, and the particle formation and growth rates were calculated for clear new particle formation (NPF) event days. The NPF events showed a pronounced seasonal cycle. The frequency of the events peaked in spring, when the ratio between event and non-event days was 53 %, whereas the events were truly sporadic on any other seasons. The annual mean particle formation and growth rates were 0.40 cm−3 s−1 and 2.43 nm h−1, respectively. The clear annual cycle was found to be mainly controlled by the seasonal evolution of the Planetary Boundary Layer (PBL) height together with local meteorological conditions. Spring NPF events were connected with increased PBL height, and therefore characterised as boundary layer events, while the rare events in other seasons represented lower free tropospheric particle formation. This provides insight on the vertical extent of NPF in the atmosphere.

scholarly journals The contribution of sulphuric acid to atmospheric particle formation and growth: a comparison between boundary layers in Northern and Central Europe

2005 ◽  
Vol 5 (1) ◽  
pp. 573-605 ◽  
Author(s):  
V. Fiedler ◽  
M. Dal Maso ◽  
M. Boy ◽  
H. Aufmhoff ◽  
J. Hoffmann ◽  
...  
Keyword(s):  
Sulphuric Acid ◽  
Central Europe ◽  
Growth Rates ◽  
Particle Number ◽  
Particle Growth ◽  
Particle Formation ◽  
Initial Growth ◽  
Size Distributions ◽  
Vapor Source ◽  
Particle Formation And Growth

Abstract. Atmospheric gaseous sulphuric acid was measured and its influence on particle formation and growth was investigated building on aerosol data. The measurements were part of the EU-project QUEST and took place at two different measurement sites in Northern and Central Europe (Hyytiälä, Finland, March–April 2003 and Heidelberg, Germany, March–April 2004). From a comprehensive data set including particle number size distributions, sulphuric acid, and meteorological data, particle growth rates, particle formation rates and source rates of condensable vapors were calculated. Growth rates were determined in two different ways, from particle size distributions as well as from a so-called timeshift analysis. Moreover, correlations between sulphuric acid and particle number concentration between 3 and 6 nm were examined and the influence of different air masses was analyzed. Measured concentrations of sulphuric acid were in the range from 2·106 to 16·106 cm-3. The gaseous sulphuric acid lifetime with respect to condensation on aerosol particles ranged from 2 to 33 min in Hyytiälä and from 28 s to 8 min in Heidelberg. Most calculated values (growth rates, formation rates, vapor source rates) were considerably higher in Central Europe (Heidelberg), due to the more polluted air and higher preexistent aerosol concentrations. Close correlations between H2SO4 and nucleation mode particles (size range: 3–6 nm) were found on many days at both sites but several observation days also lacked such correlations. The percentage contribution of sulphuric acid to particle growth was below 10% at both places, to initial growth below 20%. An air mass analysis indicated that at Heidelberg new particles were formed predominantly in air advected from southwesterly directions.

scholarly journals Particle size distributions in the Eastern Mediterranean troposphere

2008 ◽  
Vol 8 (22) ◽  
pp. 6729-6738 ◽  
Author(s):  
N. Kalivitis ◽  
W. Birmili ◽  
M. Stock ◽  
B. Wehner ◽  
A. Massling ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Particle Size ◽  
Eastern Mediterranean ◽  
Particle Formation ◽  
Particle Nucleation ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Air Masses ◽  
Crete Island ◽  
Particle Sizer

Abstract. Atmospheric particle size distributions were measured on Crete island, Greece in the Eastern Mediterranean during an intensive field campaign between 28 August and 20 October, 2005. Our instrumentation combined a differential mobility particle sizer (DMPS) and an aerodynamic particle sizer (APS) and measured number size distributions in the size range 0.018 μm–10 μm. Four time periods with distinct aerosol characteristics were discriminated, two corresponding to marine and polluted air masses, respectively. In marine air, the sub-μm size distributions showed two particle modes centered at 67 nm and 195 nm having total number concentrations between 900 and 2000 cm−3. In polluted air masses, the size distributions were mainly unimodal with a mode typically centered at 140 nm, with number concentrations varying between 1800 and 2900 cm−3. Super-μm particles showed number concentrations in the range from 0.01 to 2.5 cm−3 without any clear relation to air mass origin. A small number of short-lived particle nucleation events were recorded, where the calculated particle formation rates ranged between 1.1–1.7 cm−3 s−1. However, no particle nucleation and growth events comparable to those typical for the continental boundary layer were observed. Particles concentrations (Diameter <50 nm) were low compared to continental boundary layer conditions with an average concentration of 300 cm−3. The production of sulfuric acid and its subsequently condensation on preexisting particles was examined with the use of a simplistic box model. These calculations suggested that the day-time evolution of the Aitken particle population was governed mainly by coagulation and that particle formation was absent during most days.

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