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 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 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 Changes in the production rate of secondary aerosol particles in Central Europe in view of decreasing SO<sub>2</sub> emissions between 1996 and 2006

2010 ◽  
Vol 10 (3) ◽  
pp. 1071-1091 ◽  
Author(s):  
A. Hamed ◽  
W. Birmili ◽  
J. Joutsensaari ◽  
S. Mikkonen ◽  
A. Asmi ◽  
...  
Keyword(s):  
Growth Rate ◽  
Cloud Condensation Nuclei ◽  
Formation Rate ◽  
Global Radiation ◽  
Particle Diameter ◽  
Particle Formation ◽  
Research Station ◽  
Particle Nucleation ◽  
New Particle Formation ◽  
New Particles

Abstract. In anthropogenically influenced atmospheres, sulphur dioxide (SO2) is the main precursor of gaseous sulphuric acid (H2SO4), which in turn is a main precursor for atmospheric particle nucleation. As a result of socio-economic changes, East Germany has seen a dramatic decrease in anthropogenic SO2 emissions between 1989 and present, as documented by routine air quality measurements in many locations. We have attempted to evaluate the influence of changing SO2 concentrations on the frequency and intensity of new particle formation (NPF) using two different data sets (1996–1997; 2003–2006) of experimental particle number size distributions (diameter range 3–750 nm) from the atmospheric research station Melpitz near Leipzig, Germany. Between the two periods SO2 concentrations decreased by 65% on average, while the frequency of NPF events dropped by 45%. Meanwhile, the average formation rate of 3 nm particles decreased by 68% on average. The trends were statistically significant and therefore suggest a connection between the availability of anthropogenic SO2 and freshly formed new particles. In contrast to the decrease in new particle formation, we found an increase in the mean growth rate of freshly nucleated particles (+22%), suggesting that particle nucleation and subsequent growth into larger sizes are delineated with respect to their precursor species. Using three basic parameters, the condensation sink for H2SO4, the SO2 concentration, and the global radiation intensity, we were able to define the characteristic range of atmospheric conditions under which particle formation events take place at the Melpitz site. While the decrease in the concentrations and formation rates of the new particles was rather evident, no similar decrease was found with respect to the generation of cloud condensation nuclei (CCN; particle diameter >100 nm) as a result of atmospheric nucleation events. On the contrary, the production of CCN following nucleation events appears to have increased by tens of percents. Our aerosol dynamics model simulations suggest that such an increase can be caused by the increased particle growth rate.

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 New particle formation from the oxidation of direct emissions of pine seedlings

2009 ◽  
Vol 9 (2) ◽  
pp. 8223-8260 ◽  
Author(s):  
L. Q. Hao ◽  
P. Yli-Pirilä ◽  
P. Tiitta ◽  
S. Romakkaniemi ◽  
P. Vaattovaara ◽  
...  
Keyword(s):  
Scots Pine ◽  
Formation Rate ◽  
Particle Formation ◽  
Effective Density ◽  
Particle Nucleation ◽  
New Particle Formation ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Pine Seedlings ◽  
Condensational Growth

Abstract. Measurements of particle formation following the gas phase oxidation of volatile organic compounds (VOCs) emitted by Scots pine (Pinus sylvestris L.) seedlings are reported. Particle nucleation and condensational growth both from ozone (O3) and hydroxyl radical (OH) initiated oxidation of pine emissions (about 20–120 ppb) were investigated in a~smog chamber. During experiments, tetramethylethylene (TME) and 2-butanol were added to control the concentrations of O3 and OH. Particle nucleation and condensational growth rates were interpreted with a chemical kinetics model. Scots pine emissions mainly included α-pinene, β-pinene, Δ3-carene, limonene, myrcene, β-phellandrene and isoprene, composing more than 95% of total emissions. Modeled OH concentration in the O3+OH induced experiments was at a level of ~106 molecular cm−3. Our results demonstrate that OH-initiated oxidation of VOCs plays an important role in the nucleation process during the initial new particle formation stage. The highest average nucleation rate of 360 cm−3 s−1 was observed for the OH-dominated nucleation events and the lowest aerosol mean formation rate less than 0.5 cm−3 s−1 for the case with only O3 present as an oxidant. On the other hand, ozonolysis of monoterpenes appears to be much more efficient to the aerosol growth process following nucleation. Higher contributions of more oxygenated products to the SOA mass loadings from OH-dominating oxidation systems were found as compared to the ozonolysis systems. Comparison of mass and volume distributions from the aerosol mass spectrometer and differential mobility analyzer yields estimated effective density of these SOA to be 1.34±0.06 g cm−3 with the OH plus O3 initiated oxidation systems and 1.38±0.03 g cm−3 with the ozonolysis dominated chemistry.

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 Secondary new particle formation in Northern Finland Pallas site between the years 2000 and 2010

2011 ◽  
Vol 11 (24) ◽  
pp. 12959-12972 ◽  
Author(s):  
E. Asmi ◽  
N. Kivekäs ◽  
V.-M. Kerminen ◽  
M. Komppula ◽  
A.-P. Hyvärinen ◽  
...  
Keyword(s):  
Growth Rates ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Detailed Examination ◽  
Particle Formation ◽  
New Particle Formation ◽  
Air Masses ◽  
Event Frequency ◽  
Marine Air

Abstract. Secondary new particle formation affects atmospheric aerosol and cloud droplet numbers and thereby, the aerosol effects on climate. In this paper, the frequency of nucleation events and the associated particle formation and growth rates, along with their seasonal variation, was analysed based on over ten years of aerosol measurements conducted at the Pallas GAW station in northern Finland. The long-term measurements also allowed a detailed examination of factors possibly favouring or suppressing particle formation. Effects of meteorological parameters and air mass properties as well as vapour sources and sinks for particle formation frequency and event parameters were inspected. In addition, the potential of secondary particle formation to increase the concentration of cloud condensation nuclei (CCN) sized particles was examined. Findings from these long-term measurements confirmed previous observations: event frequency peaked in spring and the highest growth rates were observed in summer, affiliated with increased biogenic activity. Events were almost exclusively observed in marine air masses on sunny cloud-free days. A low vapour sink by the background particle population as well as an elevated sulphuric acid concentration were found to favour particle formation. These were also conditions taking place most likely in marine air masses. Inter-annual trend showed a minimum in event frequency in 2003, when also the smallest annual median of growth rate was observed. This gives further evidence of the importance and sensitivity of particle formation for the condensing vapour concentrations at Pallas site. The particle formation was observed to increase CCN80 (>80 nm particle number) concentrations especially in summer and autumn seasons when the growth rates were the highest. When the growing mode exceeded the selected 80 nm limit, on average in those cases, 211 ± 114% increase of CCN80 concentrations was observed.

scholarly journals Spring and summer contrast in new particle formation over nine forest areas in North America

2015 ◽  
Vol 15 (24) ◽  
pp. 13993-14003 ◽  
Author(s):  
F. Yu ◽  
G. Luo ◽  
S. C. Pryor ◽  
P. R. Pillai ◽  
S. H. Lee ◽  
...  
Keyword(s):  
North America ◽  
Radiative Forcing ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Formation Rate ◽  
Ultrafine Particle ◽  
Particle Formation ◽  
New Particle Formation ◽  
Forest Sites ◽  
Chamber Studies

Abstract. Recent laboratory chamber studies indicate a significant role for highly oxidized low-volatility organics in new particle formation (NPF), but the actual role of these highly oxidized low-volatility organics in atmospheric NPF remains uncertain. Here, particle size distributions (PSDs) measured in nine forest areas in North America are used to characterize the occurrence and intensity of NPF and to evaluate model simulations using an empirical formulation in which formation rate is a function of the concentrations of sulfuric acid and low-volatility organics from alpha-pinene oxidation (Nucl-Org), and using an ion-mediated nucleation mechanism (excluding organics) (Nucl-IMN). On average, NPF occurred on ~ 70 % of days during March for the four forest sites with springtime PSD measurements, while NPF occurred on only ~ 10 % of days in July for all nine forest sites. Both Nucl-Org and Nucl-IMN schemes capture the observed high frequency of NPF in spring, but the Nucl-Org scheme significantly overpredicts while the Nucl-IMN scheme slightly underpredicts NPF and particle number concentrations in summer. Statistical analyses of observed and simulated ultrafine particle number concentrations and frequency of NPF events indicate that the scheme without organics agrees better overall with observations. The two schemes predict quite different nucleation rates (including their spatial patterns), concentrations of cloud condensation nuclei, and aerosol first indirect radiative forcing in North America, highlighting the need to reduce NPF uncertainties in regional and global earth system models.

scholarly journals New particle formation in the southern Aegean Sea during the Etesians: importance for CCN production and cloud droplet number

2017 ◽  
Vol 17 (1) ◽  
pp. 175-192 ◽  
Author(s):  
Panayiotis Kalkavouras ◽  
Elissavet Bossioli ◽  
Spiros Bezantakos ◽  
Aikaterini Bougiatioti ◽  
Nikos Kalivitis ◽  
...  
Keyword(s):  
Water Vapor ◽  
Eastern Mediterranean ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Aegean Sea ◽  
Particle Formation ◽  
Cloud Formation ◽  
Particle Nucleation ◽  
Surface Winds ◽  
New Particle Formation

Abstract. This study examines how new particle formation (NPF) in the eastern Mediterranean in summer affects CCN (cloud condensation nuclei) concentrations and cloud droplet formation. For this, the concentration and size distribution of submicron aerosol particles, along with the concentration of trace gases and meteorological variables, were studied over the central (Santorini) and southern Aegean Sea (Finokalia, Crete) from 15 to 28 July 2013, a period that includes Etesian events and moderate northern surface winds. Particle nucleation bursts were recorded during the Etesian flow at both stations, with those observed at Santorini reaching up to 1.5  ×  104 particles cm−3; the fraction of nucleation-mode particles over Crete was relatively diminished, but a higher number of Aitken-mode particles were observed as a result of aging. Aerosol and photochemical pollutants covaried throughout the measurement period; lower concentrations were observed during the period of Etesian flow (e.g., 43–70 ppbv for ozone and 1.5–5.7 µg m−3 for sulfate) but were substantially enhanced during the period of moderate surface winds (i.e., increase of up to 32 for ozone and 140 % for sulfate). We find that NPF can double CCN number (at 0.1 % supersaturation), but the resulting strong competition for water vapor in cloudy updrafts decreases maximum supersaturation by 14 % and augments the potential droplet number only by 12 %. Therefore, although NPF events may strongly elevate CCN numbers, the relative impacts on cloud droplet number (compared to pre-event levels) is eventually limited by water vapor availability and depends on the prevailing cloud formation dynamics and the aerosol levels associated with the background of the region.

scholarly journals Spring and summer contrast in new particle formation over nine forest areas in North America

2015 ◽  
Vol 15 (15) ◽  
pp. 21271-21298 ◽  
Author(s):  
F. Yu ◽  
G. Luo ◽  
S. C. Pryor ◽  
P. R. Pillai ◽  
S. H. Lee ◽  
...  
Keyword(s):  
North America ◽  
Radiative Forcing ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Formation Rate ◽  
Ultrafine Particle ◽  
Particle Formation ◽  
New Particle Formation ◽  
Forest Sites ◽  
Chamber Studies

Abstract. Recent laboratory chamber studies indicate a significant role for highly oxidized low volatility organics in new particle formation (NPF) but the actual role of these highly oxidized low volatility organics in atmospheric NPF remains uncertain. Here, particle size distributions (PSDs) measured in nine forest areas in North America are used to characterize the occurrence and intensity of NPF and to evaluate model simulations using an empirical formulation in which formation rate is a function of the concentrations of sulfuric acid and low volatility organics from alpha-pinene oxidation (Nucl-Org), and using an ion-mediated nucleation mechanism (excluding organics; Nucl-IMN). On average, NPF occurred on ~ 70 % of days during March for the four forest sites with springtime PSD measurements, while NPF occurred on only ~ 10 % of days in July for all nine forest sites. Both Nucl-Org and Nucl-IMN schemes capture the observed high frequency of NPF in spring, but the Nucl-Org scheme significantly over-predicts while the Nucl-IMN scheme slightly under-predicts NPF and particle number concentrations in summer. Statistical analyses of observed and simulated ultrafine particle number concentrations and frequency of NPF events indicate that the scheme without organics agrees better overall with observations. The two schemes predict quite different nucleation rates (including their spatial patterns), concentrations of cloud condensation nuclei, and aerosol first indirect radiative forcing in North America, highlighting the need to reduce NPF uncertainties in regional and global earth system models.

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