scholarly journals Basic characteristics of atmospheric particles, trace gases and meteorology in a relatively clean Southern African Savannah environment

2008 ◽  
Vol 8 (16) ◽  
pp. 4823-4839 ◽  
Author(s):  
L. Laakso ◽  
H. Laakso ◽  
P. P. Aalto ◽  
P. Keronen ◽  
T. Petäjä ◽  
...  
Keyword(s):  
Growth Rates ◽  
Cloud Condensation Nuclei ◽  
Regional Climate ◽  
Formation Rate ◽  
Measurement Data ◽  
Particle Growth ◽  
Particle Formation ◽  
New Particle Formation ◽  
Total Particle ◽  
Pm2.5 And Pm10

Abstract. We have analyzed one year (July 2006–July 2007) of measurement data from a relatively clean background site located in dry savannah in South Africa. The annual-median trace gas concentrations were equal to 0.7 ppb for SO2, 1.4 ppb for NOx, 36 ppb for O3 and 105 ppb for CO. The corresponding PM1, PM2.5 and PM10 concentrations were 9.0, 10.5 and 18.8 μg m−3, and the annual median total particle number concentration in the size range 10–840 nm was 2340 cm−3. During Easterly winds, influence of industrial sources approximately 150 km away from the measurement site was clearly visible, especially in SO2 and NOx concentrations. Of gases, NOx and CO had a clear annual, and SO2, NOx and O3 clear diurnal cycle. Atmospheric new-particle formation was observed to take place in more than 90% of the analyzed days. The days with no new particle formation were cloudy or rainy days. The formation rate of 10 nm particles varied in the range of 0.1–28 cm−3 s−1 (median 1.9 cm−3 s−1) and nucleation mode particle growth rates were in the range 3–21 nm h−1 (median 8.5 nm h−1). Due to high formation and growth rates, observed new particle formation gives a significant contribute to the number of cloud condensation nuclei budget, having a potential to affect the regional climate forcing patterns.

scholarly journals Basic characteristics of atmospheric particles, trace gases and meteorology in a relatively clean Southern African Savannah environment

2008 ◽  
Vol 8 (2) ◽  
pp. 6313-6353 ◽  
Author(s):  
L. Laakso ◽  
H. Laakso ◽  
P. P. Aalto ◽  
P. Keronen ◽  
T. Petäjä ◽  
...  
Keyword(s):  
Growth Rates ◽  
Cloud Condensation Nuclei ◽  
Regional Climate ◽  
Formation Rate ◽  
Measurement Data ◽  
Particle Growth ◽  
Particle Formation ◽  
New Particle Formation ◽  
Total Particle ◽  
Pm2.5 And Pm10

Abstract. We have analyzed one year (July 2006–July 2007) of measurement data from a relatively clean background site located in dry savannah in South Africa. The annual-median trace gas concentrations were equal to 0.7 ppb for SO2, 1.4 ppb for NOx, 36 ppb for O3 and 105 ppb for CO. The corresponding PM1, PM2.5 and PM10 concentrations were 9.0, 10.5 and 18.8 μg m−3, and the annual median total particle number concentration in the size range 10–840 nm was 2340 cm−3. Gases and particles had a clear seasonal and diurnal variation, which was associated with field fires and biological activity together with local meteorology. Atmospheric new-particle formation was observed to take place in more than 90% of the analyzed days. The days with no new particle formation were cloudy or rainy days. The formation rate of 10 nm particles varied in the range of 0.1–28 cm−3 s−1 (median 1.9 cm−3 s−1) and nucleation mode particle growth rates were in the range 3–21 nm h−1 (median 8.5 nm h−1). Due to high formation and growth rates, observed new particle formation gives a significant contribute to the number of cloud condensation nuclei budget, having a potential to affect the regional climate forcing patterns.

scholarly journals Molecular understanding of the suppression of new-particle formation by isoprene

2020 ◽  
Author(s):  
Martin Heinritzi ◽  
Lubna Dada ◽  
Mario Simon ◽  
Dominik Stolzenburg ◽  
Andrea C. Wagner ◽  
...  
Keyword(s):  
Growth Rates ◽  
Cloud Condensation Nuclei ◽  
Formation Rate ◽  
Organic Aerosol ◽  
Particle Formation ◽  
Early Growth ◽  
Chemical System ◽  
Particle Nucleation ◽  
New Particle Formation ◽  
Ambient Conditions

Abstract. Nucleation of atmospheric vapors produces more than half of global cloud condensation nuclei and so has an important influence on climate. Recent studies show that monoterpene (C10H16) oxidation yields highly-oxygenated products that can nucleate with or without sulfuric acid. Monoterpenes are emitted mainly by trees, frequently together with isoprene (C5H8), which has the highest global emission of all organic vapors. Previous studies have shown that isoprene suppresses new-particle formation from monoterpenes, but the cause of this suppression is under debate. Here, in experiments performed under atmospheric conditions in the CERN CLOUD chamber, we show that isoprene reduces the yield of highly-oxygenated dimers with 19 or 20 carbon atoms – which drive particle nucleation and early growth – while increasing the production of dimers with 14 or 15 carbon atoms. The dimers (termed C20 and C15, respectively) are produced by termination reactions between pairs of peroxy radicals (RO2·) arising from monoterpenes or isoprene. Compared with pure monoterpene conditions, isoprene reduces nucleation rates at 1.7 nm (depending on the isoprene/monoterpene ratio) and approximately halves particle growth rates between 1.3 and 3.2 nm. However, above 3.2 nm, C15 dimers contribute to secondary organic aerosol and the growth rates are unaffected by isoprene. We further show that increased hydroxyl radical (OH·) reduces particle formation in our chemical system rather than enhances it as previously proposed, since it increases isoprene derived RO2· radicals that reduce C20 formation. RO2· termination emerges as the critical step that determines the HOM distribution and the corresponding nucleation capability. Species that reduce the C20 yield, such as NO, HO2 and as we show isoprene, can thus effectively reduce biogenic nucleation and early growth. Therefore the formation rate of organic aerosol in a particular region of the atmosphere under study will vary according to the precise ambient conditions.

scholarly journals New particle formation in the front range of the Colorado Rocky Mountains

2007 ◽  
Vol 7 (6) ◽  
pp. 15581-15617 ◽  
Author(s):  
M. Boy ◽  
T. Karl ◽  
A. Turnipseed ◽  
R. L. Mauldin ◽  
E. Kosciuch ◽  
...  
Keyword(s):  
Rocky Mountains ◽  
Cloud Condensation Nuclei ◽  
Measurement Data ◽  
Particle Growth ◽  
Particle Formation ◽  
Conclusive Evidence ◽  
Front Range ◽  
New Particle Formation ◽  
Particle Measurement ◽  
Colorado Rocky Mountains

Abstract. New particle formation is of interest because of its influence on the properties of aerosol population, and due to the possible contribution of newly formed particles to cloud condensation nuclei. Currently no conclusive evidence exists as to the mechanism or mechanisms of nucleation and subsequent particle growth. However, nucleation rates exhibit a clear dependence on ambient sulphuric acid concentrations and particle growth is often attributed to the condensation of organic vapours. A detailed study of new particle formation in the Front Range of the Colorado Rocky Mountains is presented here. Gas and particle measurement data for 32 days was analyzed to identify event days, possible event days, and non-event days. A detailed analysis of nucleation and growth is provided for four days on which new particle formation was clearly observed. Evidence for the role of sesquiterpenes in new particle formation is presented.

scholarly journals Molecular understanding of the suppression of new-particle formation by isoprene

2020 ◽  
Vol 20 (20) ◽  
pp. 11809-11821 ◽  
Author(s):  
Martin Heinritzi ◽  
Lubna Dada ◽  
Mario Simon ◽  
Dominik Stolzenburg ◽  
Andrea C. Wagner ◽  
...  
Keyword(s):  
Growth Rates ◽  
Cloud Condensation Nuclei ◽  
Formation Rate ◽  
Organic Aerosol ◽  
Particle Formation ◽  
Early Growth ◽  
Chemical System ◽  
Particle Nucleation ◽  
New Particle Formation ◽  
Ambient Conditions

Abstract. Nucleation of atmospheric vapours produces more than half of global cloud condensation nuclei and so has an important influence on climate. Recent studies show that monoterpene (C10H16) oxidation yields highly oxygenated products that can nucleate with or without sulfuric acid. Monoterpenes are emitted mainly by trees, frequently together with isoprene (C5H8), which has the highest global emission of all organic vapours. Previous studies have shown that isoprene suppresses new-particle formation from monoterpenes, but the cause of this suppression is under debate. Here, in experiments performed under atmospheric conditions in the CERN CLOUD chamber, we show that isoprene reduces the yield of highly oxygenated dimers with 19 or 20 carbon atoms – which drive particle nucleation and early growth – while increasing the production of dimers with 14 or 15 carbon atoms. The dimers (termed C20 and C15, respectively) are produced by termination reactions between pairs of peroxy radicals (RO2⚫) arising from monoterpenes or isoprene. Compared with pure monoterpene conditions, isoprene reduces nucleation rates at 1.7 nm (depending on the isoprene ∕ monoterpene ratio) and approximately halves particle growth rates between 1.3 and 3.2 nm. However, above 3.2 nm, C15 dimers contribute to secondary organic aerosol, and the growth rates are unaffected by isoprene. We further show that increased hydroxyl radical (OH⚫) reduces particle formation in our chemical system rather than enhances it as previously proposed, since it increases isoprene-derived RO2⚫ radicals that reduce C20 formation. RO2⚫ termination emerges as the critical step that determines the highly oxygenated organic molecule (HOM) distribution and the corresponding nucleation capability. Species that reduce the C20 yield, such as NO, HO2 and as we show isoprene, can thus effectively reduce biogenic nucleation and early growth. Therefore the formation rate of organic aerosol in a particular region of the atmosphere under study will vary according to the precise ambient conditions.

scholarly journals Seasonal cycle and modal structure of particle number size distribution at Dome C, Antarctica

2013 ◽  
Vol 13 (15) ◽  
pp. 7473-7487 ◽  
Author(s):  
E. Järvinen ◽  
A. Virkkula ◽  
T. Nieminen ◽  
P. P. Aalto ◽  
E. Asmi ◽  
...  
Keyword(s):  
Size Distribution ◽  
Seasonal Cycle ◽  
Particle Number ◽  
Formation Rate ◽  
Particle Growth ◽  
Particle Formation ◽  
Distribution Data ◽  
New Particle Formation ◽  
Total Particle Number ◽  
Total Particle

Abstract. We studied new particle formation and modal behavior of ultrafine aerosol particles on the high East Antarctic plateau at the Concordia station, Dome C (75°06' S, 123°23' E). Aerosol particle number size distributions were measured in the size range 10–600 nm from 14 December 2007 to 7 November 2009. We used an automatic algorithm for fitting up to three modes to the size distribution data. The total particle number concentration was low with the median of 109 cm−3. There was a clear seasonal cycle in the total particle number and the volume concentrations. The concentrations were at their highest during the austral summer with the median values of 260 cm−3 and 0.086 μm3 cm−3, and at their lowest during the austral winter with corresponding values of 15 cm−3 and 0.009 μm3 cm−3. New particle formation events were determined from the size distribution data. During the measurement period, natural new particle formation was observed on 60 days and for 15 of these days the particle growth rates from 10 to 25 nm in size could be determined. The median particle growth rate during all these events was 2.5 nm h−1 and the median formation rate of 10 nm particles was 0.023 cm−3 s−1. Most of the events were similar to those observed at other continental locations, yet also some variability in event types was observed. Exceptional features in Dome C were the winter events that occurred during dark periods, as well as the events for which the growth could be followed during several consecutive days. We called these latter events slowly growing events. This paper is the first one to analyze long-term size distribution data from Dome C, and also the first paper to show that new particle formation events occur in central Antarctica.

scholarly journals Natural new particle formation at the coastal Antarctic site Neumayer

2015 ◽  
Vol 15 (11) ◽  
pp. 15655-15681
Author(s):  
R. Weller ◽  
K. Schmidt ◽  
K. Teinilä ◽  
R. Hillamo
Keyword(s):  
Growth Rates ◽  
Cloud Condensation Nuclei ◽  
Particle Diameter ◽  
Particle Growth ◽  
Particle Formation ◽  
New Particle Formation ◽  
Particle Size Distributions ◽  
Polar Night ◽  
Volatile Precursor ◽  
Simple Estimation

Abstract. We measured condensation particle (CP) concentrations and particle size distributions at the coastal Antarctic station Neumayer (70°39' S, 8°15' W) during two summer campaigns (from 20 January to 26 March 2012 and 1 February to 30 April 2014) and during polar night between 12 August and 27 September 2014 in the particle diameter (Dp) range from 2.94 to 60.4 nm (2012) and from 6.26 to 212.9 nm (2014). During both summer campaigns we identified all in all 44 new particle formation (NPF) events. From 10 NPF events, particle growth rates could be determined to be around 0.90 ± 0.46 nm h−1 (mean ± SD; range: 0.4 to 1.9 nm h−1). With the exception of one case, particle growth was generally restricted to the nucleation mode (Dp < 25 nm) and the duration of NPF events was typically around 6.0 ± 1.5 h (mean ± SD; range: 4 to 9 h). Thus in the main, particles did not grow up to sizes required for acting as cloud condensation nuclei. NPF during summer usually occurred in the afternoon in coherence with local photochemistry. During winter, two NPF events could be detected, though showing no ascertainable particle growth. A simple estimation indicated that apart from sulfuric acid, the derived growth rates required other low volatile precursor vapours.

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 New particle formation in the Front Range of the Colorado Rocky Mountains

2008 ◽  
Vol 8 (6) ◽  
pp. 1577-1590 ◽  
Author(s):  
M. Boy ◽  
T. Karl ◽  
A. Turnipseed ◽  
R. L. Mauldin ◽  
E. Kosciuch ◽  
...  
Keyword(s):  
Rocky Mountains ◽  
Cloud Condensation Nuclei ◽  
Measurement Data ◽  
Particle Growth ◽  
Particle Formation ◽  
Conclusive Evidence ◽  
Front Range ◽  
New Particle Formation ◽  
Particle Measurement ◽  
Colorado Rocky Mountains

Abstract. New particle formation is of interest because of its influence on the properties of aerosol population, and due to the possible contribution of newly formed particles to cloud condensation nuclei. Currently no conclusive evidence exists as to the mechanism or mechanisms of nucleation and subsequent particle growth. However, nucleation rates exhibit a clear dependence on ambient sulphuric acid concentrations and particle growth is often attributed to the condensation of organic vapours. A detailed study of new particle formation in the Front Range of the Colorado Rocky Mountains is presented here. Gas and particle measurement data for 32 days was analyzed to identify event days, possible event days, and non-event days. A detailed analysis of nucleation and growth is provided for four days on which new particle formation was clearly observed. Evidence for the role of sesquiterpenes in new particle formation is presented.

scholarly journals Aerosols and nucleation in eastern China: first insights from the new SORPES-NJU station

2014 ◽  
Vol 14 (4) ◽  
pp. 2169-2183 ◽  
Author(s):  
E. Herrmann ◽  
A. J. Ding ◽  
V.-M. Kerminen ◽  
T. Petäjä ◽  
X. Q. Yang ◽  
...  
Keyword(s):  
Meteorological Data ◽  
Cloud Condensation Nuclei ◽  
Eastern China ◽  
Formation Rate ◽  
Particle Growth ◽  
Particle Formation ◽  
Accurate Estimate ◽  
New Particle Formation ◽  
The Mean ◽  
Measurement Period

Abstract. Aerosols and new particle formation were studied in the western part of the Yangtze River Delta (YRD) at the Station for Observing Regional Processes of the Earth System, Nanjing University (SORPES-NJU). Air ions in the diameter range 0.8–42 nm were measured using an air ion spectrometer, and a differential mobility particle sizer (DMPS) provided particle number size distributions between 6 and 800 nm. Additionally, meteorological data, trace gas concentrations, and PM2.5 values were recorded. During the measurement period from 18 November 2011 to 31 March 2012, the mean total particle concentration was found to be 23 000 cm−3 and the mean PM2.5 value was 90 μg m−3, well above national limits. We observed 26 new particle formation events occurred during the measurement period, producing 6 nm particles at a rate of about 1 cm−3 s−1. Typical particle growth rates were between 6 and 7 nm h−1. On average, new particle formation and growth were estimated to enhance cloud condensation nuclei concentration by about a factor of two during these event days. Ion measurements showed the typical cluster band below 2 nm, with total ion concentrations between about 600 and 1000 cm−3. A peculiar feature of the ion measurements were heightened ion cluster concentrations during the nights before the event days. At 2 nm, the formation rate of charged particles was only about 0.2% of the total rate, pointing towards an only marginal role of ion-induced nucleation. Based on observations, a simple empirical criterion was deducted to estimate particle formation probability. Dominated by radiation and relative humidity, the criterion can predict the occurrence of particle formation with a 90% accuracy. In a similar fashion, a reasonably accurate estimate of particle formation rates was derived. Combined, these parameters allow for a description of particle formation based on a few basic measured variables.

scholarly journals Seasonal cycle and modal structure of particle number size distribution at Dome C, Antarctica

2013 ◽  
Vol 13 (3) ◽  
pp. 5729-5768
Author(s):  
E. Järvinen ◽  
A. Virkkula ◽  
T. Nieminen ◽  
P. P. Aalto ◽  
E. Asmi ◽  
...  
Keyword(s):  
Size Distribution ◽  
Seasonal Cycle ◽  
Particle Number ◽  
Formation Rate ◽  
Particle Growth ◽  
Particle Formation ◽  
Distribution Data ◽  
New Particle Formation ◽  
Total Particle Number ◽  
Total Particle

Abstract. We studied new particle formation and modal behavior of ultrafine aerosol particles on the high Antarctic East-Plateau at the Concordia station, Dome C (75°06' S, 123°23' E). Aerosol particle number size distributions were measured in the size range 10–600 nm from 14 December 2007 to 7 November 2009. We used an automatic algorithm for fitting up to three modes to the size distribution data. The total particle number concentration was low with the median of 109 cm−3. There was a clear seasonal cycle in the total particle number and the volume concentrations. The concentrations were at their highest during the austral summer with the median values of 260 cm−3 and 0.086 μm3 cm−3, and at their lowest during the austral winter with corresponding values of 15 cm−3 and 0.009 μm3 cm−3. New particle formation events were determined from the size distribution data. During the measurement period, new particle formation was seen on 80 days and for 15 of these days the particle growth rates from 10 to 25 nm size could be determined. The median particle growth rate during all these events was 2.5 nm h−1 and the median formation rate of 10 nm particles was 0.023 cm−3 s−1. Most of the events were similar to those observed in other continental locations, yet also some variability in event types was observed. Exceptional features in Dome C were the winter events that occurred during dark periods, as well as the events for which the growth could be followed during several consecutive days. We called these latter events as slowly-growing events. This paper is the first one to analyze long-term size distribution data from Dome C, and also the first paper to show that new particle formation events occur in the central Antarctica.

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