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Markku Kulmala - One of the best experts on this subject based on the ideXlab platform.
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effect of ions on sulfuric acid water binary Particle Formation 1 theory for kinetic and nucleation type Particle Formation and atmospheric implications
Journal of Geophysical Research, 2016Co-Authors: Joonas Merikanto, Jonathan Duplissy, Anni Maattanen, Henning Henschel, Neil M Donahue, David Brus, Siegfried Schobesberger, Markku KulmalaAbstract:We derive a version of Classical Nucleation Theory normalized by quantum chemical results on sulfuric acid-water hydration to describe neutral and ion-induced Particle Formation in the binary sulfuric acid-water system. The theory is extended to treat the kinetic regime where the nucleation free energy barrier vanishes at high sulfuric acid concentrations or low temperatures. In the kinetic regime Particle Formation rates become proportional to sulfuric acid concentration to second power in the neutral system or first power in the ion-induced system. We derive simple general expressions for the prefactors in kinetic-type and activation-type Particle Formation calculations applicable also to more complex systems stabilized by other species. The theory predicts that the binary water-sulfuric acid system can produce strong new Particle Formation in the free troposphere both through barrier crossing and through kinetic pathways. At cold stratospheric and upper free tropospheric temperatures neutral Formation dominates the binary Particle Formation rates. At midtropospheric temperatures the ion-induced pathway becomes the dominant mechanism. However, even the ion-induced binary mechanism does not produce significant Particle Formation in warm boundary layer conditions, as it requires temperatures below 0°C to take place at atmospheric concentrations. The theory successfully reproduces the characteristics of measured charged and neutral binary Particle Formation in CERN CLOUD3 and CLOUD5 experiments, as discussed in a companion paper.
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Effect of ions on sulfuric acid‐water binary Particle Formation: 1. Theory for kinetic‐ and nucleation‐type Particle Formation and atmospheric implications
Journal of Geophysical Research: Atmospheres, 2016Co-Authors: Joonas Merikanto, Markku Kulmala, Jonathan Duplissy, Anni Maattanen, Henning Henschel, Neil M Donahue, David Brus, Siegfried Schobesberger, Hanna VehkamäkiAbstract:We derive a version of Classical Nucleation Theory normalized by quantum chemical results on sulfuric acid-water hydration to describe neutral and ion-induced Particle Formation in the binary sulfuric acid-water system. The theory is extended to treat the kinetic regime where the nucleation free energy barrier vanishes at high sulfuric acid concentrations or low temperatures. In the kinetic regime Particle Formation rates become proportional to sulfuric acid concentration to second power in the neutral system or first power in the ion-induced system. We derive simple general expressions for the prefactors in kinetic-type and activation-type Particle Formation calculations applicable also to more complex systems stabilized by other species. The theory predicts that the binary water-sulfuric acid system can produce strong new Particle Formation in the free troposphere both through barrier crossing and through kinetic pathways. At cold stratospheric and upper free tropospheric temperatures neutral Formation dominates the binary Particle Formation rates. At midtropospheric temperatures the ion-induced pathway becomes the dominant mechanism. However, even the ion-induced binary mechanism does not produce significant Particle Formation in warm boundary layer conditions, as it requires temperatures below 0°C to take place at atmospheric concentrations. The theory successfully reproduces the characteristics of measured charged and neutral binary Particle Formation in CERN CLOUD3 and CLOUD5 experiments, as discussed in a companion paper.
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How do organic vapors contribute to new-Particle Formation?
Faraday discussions, 2013Co-Authors: Neil M Donahue, Markku Kulmala, Siegfried Schobesberger, Ilona Riipinen, Ismael K. Ortega, Wayne Chuang, Francesco Riccobono, Josef Dommen, Urs Baltensperger, Douglas R. WorsnopAbstract:Highly oxidised organic vapors can effectively stabilize sulphuric acid in heteronuclear clusters and drive new-Particle Formation. We present quantum chemical calculations of cluster stability, showing that multifunctional species can stabilize sulphuric acid and also present additional polar functional groups for subsequent cluster growth. We also model the multi-generation oxidation of vapors associated with secondary organic aerosol Formation using a two-dimensional volatility basis set. The steady-state saturation ratios and absolute concentrations of extremely low volatility products are sufficient to drive new-Particle Formation with sulphuric acid at atmospherically relevant rates.
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Observations of nighttime new Particle Formation in the troposphere
Journal of Geophysical Research, 2008Co-Authors: Shanhu Lee, Markku Kulmala, D. R. Benson, L.-h. Young, Teresa Campos, David C. Rogers, Tanja Suni, Heikki Junninen, Jorgen B. JensenAbstract:[1] We present atmospheric observations which indicate efficient new Particle Formation during the nighttime in the troposphere under low condensation sinks, in contrast to the current prevailing assumption that aerosol nucleation takes place only during the daytime and typically from sulfuric acid. High concentrations of ultrafine Particles with diameters from 4 to 9 nm (∼1000 cm−3) were measured from the three days of nighttime observations in the upper troposphere during the NSF/NCAR GV Progressive Science Missions. Long-term ground-based observations of charged and neutral clusters and aerosols made in Tumbarumba, Australia, also showed surprisingly high frequency of nighttime new Particle Formation (30%) with low condensation sinks. Nighttime nucleation can be significant for global aerosol load and cloud condensation nuclei productions and thus needs to be included in global climate models. Future studies are required to understand the nighttime nucleation mechanisms.
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Contribution of Particle Formation to global cloud condensation nuclei concentrations
Geophysical Research Letters, 2008Co-Authors: Dominick V. Spracklen, Markku Kulmala, Joonas Merikanto, Kenneth S. Carslaw, Veli-matti Kerminen, S.-l. Sihto, Ilona Riipinen, Graham Mann, Martyn P. Chipperfield, Alfred WiedensohlerAbstract:[1] We use a global aerosol microphysics model to predict the contribution of boundary layer (BL) Particle Formation to regional and global distributions of cloud condensation nuclei (CCN). Including an observationally derived Particle Formation scheme, where the Formation rate of molecular clusters is proportional to gas-phase sulfuric acid to the power one, improves modeled Particle size distribution and total Particle number concentration at three continental sites in Europe. Particle Formation increases springtime BL global mean CCN (0.2% supersaturation) concentrations by 3–20% and CCN (1%) by 5–50%. Uncertainties in Particle Formation and growth rates must be reduced before the accuracy of these predictions can be improved. These results demonstrate the potential importance of BL Particle Formation as a global source of CCN.
Joonas Merikanto - One of the best experts on this subject based on the ideXlab platform.
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new parameterizations for neutral and ion induced sulfuric acid water Particle Formation in nucleation and kinetic regimes
Journal of Geophysical Research, 2017Co-Authors: Anni Maattanen, Joonas Merikanto, Jonathan Duplissy, Henning Henschel, Ismael K. Ortega, Risto Makkonen, Hanna VehkamäkiAbstract:We have developed new parameterizations of electrically neutral homogeneous and ion-induced sulfuric acid - water Particle Formation for large ranges of environmental conditions, based on an improved model that has been validated against a Particle Formation rate data set produced by Cosmics Leaving OUtdoor Droplets (CLOUD) experiments at CERN. The model uses a thermodynamically consistent version of the Classical Nucleation Theory normalized using quantum chemical data. Unlike the earlier parameterizations for H 2 SO 4 -H 2 O nucleation, the model is applicable to extreme dry conditions where the one-component sulfuric acid limit is approached. Parameterizations are presented for the critical cluster sulfuric acid mole fraction, the critical cluster radius, the total number of molecules in the critical cluster, and the Particle Formation rate. If the critical cluster contains only one sulfuric acid molecule, a simple formula for kinetic Particle Formation can be used: this threshold has also been parameterized. The parameterization for electrically neutral Particle Formation is valid for the following ranges: temperatures 165-400 K, sulfuric acid concentrations 10 4 -10 13 cm −3 and relative humidities 0.001-100%. The ion-induced Particle Formation parameterization is valid for temperatures 195-400 K, sulfuric acid concentrations 10 4 -10 16 cm −3 and relative humidities 10 −5 -100%. The new parameterizations are thus applicable for the full range of conditions in the Earth's atmosphere relevant for binary sulfuric acid - water Particle Formation, including both tropospheric and stratospheric conditions. They are also suitable for describing Particle Formation in the atmosphere of Venus.
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effect of ions on sulfuric acid water binary Particle Formation 1 theory for kinetic and nucleation type Particle Formation and atmospheric implications
Journal of Geophysical Research, 2016Co-Authors: Joonas Merikanto, Jonathan Duplissy, Anni Maattanen, Henning Henschel, Neil M Donahue, David Brus, Siegfried Schobesberger, Markku KulmalaAbstract:We derive a version of Classical Nucleation Theory normalized by quantum chemical results on sulfuric acid-water hydration to describe neutral and ion-induced Particle Formation in the binary sulfuric acid-water system. The theory is extended to treat the kinetic regime where the nucleation free energy barrier vanishes at high sulfuric acid concentrations or low temperatures. In the kinetic regime Particle Formation rates become proportional to sulfuric acid concentration to second power in the neutral system or first power in the ion-induced system. We derive simple general expressions for the prefactors in kinetic-type and activation-type Particle Formation calculations applicable also to more complex systems stabilized by other species. The theory predicts that the binary water-sulfuric acid system can produce strong new Particle Formation in the free troposphere both through barrier crossing and through kinetic pathways. At cold stratospheric and upper free tropospheric temperatures neutral Formation dominates the binary Particle Formation rates. At midtropospheric temperatures the ion-induced pathway becomes the dominant mechanism. However, even the ion-induced binary mechanism does not produce significant Particle Formation in warm boundary layer conditions, as it requires temperatures below 0°C to take place at atmospheric concentrations. The theory successfully reproduces the characteristics of measured charged and neutral binary Particle Formation in CERN CLOUD3 and CLOUD5 experiments, as discussed in a companion paper.
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Effect of ions on sulfuric acid‐water binary Particle Formation: 1. Theory for kinetic‐ and nucleation‐type Particle Formation and atmospheric implications
Journal of Geophysical Research: Atmospheres, 2016Co-Authors: Joonas Merikanto, Markku Kulmala, Jonathan Duplissy, Anni Maattanen, Henning Henschel, Neil M Donahue, David Brus, Siegfried Schobesberger, Hanna VehkamäkiAbstract:We derive a version of Classical Nucleation Theory normalized by quantum chemical results on sulfuric acid-water hydration to describe neutral and ion-induced Particle Formation in the binary sulfuric acid-water system. The theory is extended to treat the kinetic regime where the nucleation free energy barrier vanishes at high sulfuric acid concentrations or low temperatures. In the kinetic regime Particle Formation rates become proportional to sulfuric acid concentration to second power in the neutral system or first power in the ion-induced system. We derive simple general expressions for the prefactors in kinetic-type and activation-type Particle Formation calculations applicable also to more complex systems stabilized by other species. The theory predicts that the binary water-sulfuric acid system can produce strong new Particle Formation in the free troposphere both through barrier crossing and through kinetic pathways. At cold stratospheric and upper free tropospheric temperatures neutral Formation dominates the binary Particle Formation rates. At midtropospheric temperatures the ion-induced pathway becomes the dominant mechanism. However, even the ion-induced binary mechanism does not produce significant Particle Formation in warm boundary layer conditions, as it requires temperatures below 0°C to take place at atmospheric concentrations. The theory successfully reproduces the characteristics of measured charged and neutral binary Particle Formation in CERN CLOUD3 and CLOUD5 experiments, as discussed in a companion paper.
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Contribution of Particle Formation to global cloud condensation nuclei concentrations
Geophysical Research Letters, 2008Co-Authors: Dominick V. Spracklen, Markku Kulmala, Joonas Merikanto, Kenneth S. Carslaw, Veli-matti Kerminen, S.-l. Sihto, Ilona Riipinen, Graham Mann, Martyn P. Chipperfield, Alfred WiedensohlerAbstract:[1] We use a global aerosol microphysics model to predict the contribution of boundary layer (BL) Particle Formation to regional and global distributions of cloud condensation nuclei (CCN). Including an observationally derived Particle Formation scheme, where the Formation rate of molecular clusters is proportional to gas-phase sulfuric acid to the power one, improves modeled Particle size distribution and total Particle number concentration at three continental sites in Europe. Particle Formation increases springtime BL global mean CCN (0.2% supersaturation) concentrations by 3–20% and CCN (1%) by 5–50%. Uncertainties in Particle Formation and growth rates must be reduced before the accuracy of these predictions can be improved. These results demonstrate the potential importance of BL Particle Formation as a global source of CCN.
Hanna Vehkamäki - One of the best experts on this subject based on the ideXlab platform.
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Guanidine: A Highly Efficient Stabilizer in Atmospheric New-Particle Formation
The journal of physical chemistry. A, 2018Co-Authors: Nanna Myllys, Hanna Vehkamäki, Tuomo Ponkkonen, Monica Passananti, Jonas Elm, Tinja OleniusAbstract:The role of a strong organobase, guanidine, in sulfuric acid-driven new-Particle Formation is studied using state-of-the-art quantum chemical methods and molecular cluster Formation simulations. Cluster Formation mechanisms at the molecular level are resolved, and theoretical results on cluster stability are confirmed with mass spectrometer measurements. New-Particle Formation from guanidine and sulfuric acid molecules occurs without thermodynamic barriers under studied conditions, and clusters are growing close to a 1:1 composition of acid and base. Evaporation rates of the most stable clusters are extremely low, which can be explained by the proton transfers and symmetrical cluster structures. We compare the ability of guanidine and dimethylamine to enhance sulfuric acid-driven Particle Formation and show that more than 2000-fold concentration of dimethylamine is needed to yield as efficient Particle Formation as in the case of guanidine. At similar conditions, guanidine yields 8 orders of magnitude hig...
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new parameterizations for neutral and ion induced sulfuric acid water Particle Formation in nucleation and kinetic regimes
Journal of Geophysical Research, 2017Co-Authors: Anni Maattanen, Joonas Merikanto, Jonathan Duplissy, Henning Henschel, Ismael K. Ortega, Risto Makkonen, Hanna VehkamäkiAbstract:We have developed new parameterizations of electrically neutral homogeneous and ion-induced sulfuric acid - water Particle Formation for large ranges of environmental conditions, based on an improved model that has been validated against a Particle Formation rate data set produced by Cosmics Leaving OUtdoor Droplets (CLOUD) experiments at CERN. The model uses a thermodynamically consistent version of the Classical Nucleation Theory normalized using quantum chemical data. Unlike the earlier parameterizations for H 2 SO 4 -H 2 O nucleation, the model is applicable to extreme dry conditions where the one-component sulfuric acid limit is approached. Parameterizations are presented for the critical cluster sulfuric acid mole fraction, the critical cluster radius, the total number of molecules in the critical cluster, and the Particle Formation rate. If the critical cluster contains only one sulfuric acid molecule, a simple formula for kinetic Particle Formation can be used: this threshold has also been parameterized. The parameterization for electrically neutral Particle Formation is valid for the following ranges: temperatures 165-400 K, sulfuric acid concentrations 10 4 -10 13 cm −3 and relative humidities 0.001-100%. The ion-induced Particle Formation parameterization is valid for temperatures 195-400 K, sulfuric acid concentrations 10 4 -10 16 cm −3 and relative humidities 10 −5 -100%. The new parameterizations are thus applicable for the full range of conditions in the Earth's atmosphere relevant for binary sulfuric acid - water Particle Formation, including both tropospheric and stratospheric conditions. They are also suitable for describing Particle Formation in the atmosphere of Venus.
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Effect of ions on sulfuric acid‐water binary Particle Formation: 1. Theory for kinetic‐ and nucleation‐type Particle Formation and atmospheric implications
Journal of Geophysical Research: Atmospheres, 2016Co-Authors: Joonas Merikanto, Markku Kulmala, Jonathan Duplissy, Anni Maattanen, Henning Henschel, Neil M Donahue, David Brus, Siegfried Schobesberger, Hanna VehkamäkiAbstract:We derive a version of Classical Nucleation Theory normalized by quantum chemical results on sulfuric acid-water hydration to describe neutral and ion-induced Particle Formation in the binary sulfuric acid-water system. The theory is extended to treat the kinetic regime where the nucleation free energy barrier vanishes at high sulfuric acid concentrations or low temperatures. In the kinetic regime Particle Formation rates become proportional to sulfuric acid concentration to second power in the neutral system or first power in the ion-induced system. We derive simple general expressions for the prefactors in kinetic-type and activation-type Particle Formation calculations applicable also to more complex systems stabilized by other species. The theory predicts that the binary water-sulfuric acid system can produce strong new Particle Formation in the free troposphere both through barrier crossing and through kinetic pathways. At cold stratospheric and upper free tropospheric temperatures neutral Formation dominates the binary Particle Formation rates. At midtropospheric temperatures the ion-induced pathway becomes the dominant mechanism. However, even the ion-induced binary mechanism does not produce significant Particle Formation in warm boundary layer conditions, as it requires temperatures below 0°C to take place at atmospheric concentrations. The theory successfully reproduces the characteristics of measured charged and neutral binary Particle Formation in CERN CLOUD3 and CLOUD5 experiments, as discussed in a companion paper.
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The role of highly oxidized organics in new Particle Formation
2013Co-Authors: Ismael K. Ortega, Hanna VehkamäkiAbstract:The role of organic compounds in atmospheric new Particle Formation is still not clear, some studies concludes that they play no role in new Particle Formation, while others conclude that they are crucial. In the present work we have used quantum chemical calculations to estimate how stable clusters can form different organic compounds. We have chosen three different organic compounds with increasing O:C ratio. Our results indicate that highly oxidized organic compounds can form stable clusters with sulfuric acid. Thus, they may play an important role in new Particle Formation.
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atmospheric Particle Formation events at varrio measurement station in finnish lapland 1998 2002
Atmospheric Chemistry and Physics, 2004Co-Authors: Hanna Vehkamäki, R Flanagan, A P Hyvarinen, J Lauros, P Merikanto, Tareq Hussein, David Mas Maso, Mikko Mönkkönen, K PihlatieAbstract:During the calendar years 1998-2002, 147 clear 8nm diameter Particle Formation events have been identified at the SMEAR I station in Varrio, northern Finland. The events have been classified in detail according to the Particle Formation rate, growth rate, event starting time, different trace gas concentrations and pre-existing Particle concentrations as well as various meteorological conditions. The frequency of Particle Formation and growth events was highest during the spring months between March and May, suggesting that increasing biological activity might produce the precursor gases for Particle Formation. The apparent 8nm Particle Formation rates were around 0.1 /cm 3 s, and they were uncorrelated with growth rates that varied between 0.5 and 10nm/h. The air masses with clearly elevated sulphur dioxide concentrations (above 1.6ppb) came, as expected, from the direction of the Nikel and Monschegorsk smelters. Only 15 Formation events can be explained by the pollution plume from these sources.
Jonathan Duplissy - One of the best experts on this subject based on the ideXlab platform.
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new parameterizations for neutral and ion induced sulfuric acid water Particle Formation in nucleation and kinetic regimes
Journal of Geophysical Research, 2017Co-Authors: Anni Maattanen, Joonas Merikanto, Jonathan Duplissy, Henning Henschel, Ismael K. Ortega, Risto Makkonen, Hanna VehkamäkiAbstract:We have developed new parameterizations of electrically neutral homogeneous and ion-induced sulfuric acid - water Particle Formation for large ranges of environmental conditions, based on an improved model that has been validated against a Particle Formation rate data set produced by Cosmics Leaving OUtdoor Droplets (CLOUD) experiments at CERN. The model uses a thermodynamically consistent version of the Classical Nucleation Theory normalized using quantum chemical data. Unlike the earlier parameterizations for H 2 SO 4 -H 2 O nucleation, the model is applicable to extreme dry conditions where the one-component sulfuric acid limit is approached. Parameterizations are presented for the critical cluster sulfuric acid mole fraction, the critical cluster radius, the total number of molecules in the critical cluster, and the Particle Formation rate. If the critical cluster contains only one sulfuric acid molecule, a simple formula for kinetic Particle Formation can be used: this threshold has also been parameterized. The parameterization for electrically neutral Particle Formation is valid for the following ranges: temperatures 165-400 K, sulfuric acid concentrations 10 4 -10 13 cm −3 and relative humidities 0.001-100%. The ion-induced Particle Formation parameterization is valid for temperatures 195-400 K, sulfuric acid concentrations 10 4 -10 16 cm −3 and relative humidities 10 −5 -100%. The new parameterizations are thus applicable for the full range of conditions in the Earth's atmosphere relevant for binary sulfuric acid - water Particle Formation, including both tropospheric and stratospheric conditions. They are also suitable for describing Particle Formation in the atmosphere of Venus.
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effect of ions on sulfuric acid water binary Particle Formation 1 theory for kinetic and nucleation type Particle Formation and atmospheric implications
Journal of Geophysical Research, 2016Co-Authors: Joonas Merikanto, Jonathan Duplissy, Anni Maattanen, Henning Henschel, Neil M Donahue, David Brus, Siegfried Schobesberger, Markku KulmalaAbstract:We derive a version of Classical Nucleation Theory normalized by quantum chemical results on sulfuric acid-water hydration to describe neutral and ion-induced Particle Formation in the binary sulfuric acid-water system. The theory is extended to treat the kinetic regime where the nucleation free energy barrier vanishes at high sulfuric acid concentrations or low temperatures. In the kinetic regime Particle Formation rates become proportional to sulfuric acid concentration to second power in the neutral system or first power in the ion-induced system. We derive simple general expressions for the prefactors in kinetic-type and activation-type Particle Formation calculations applicable also to more complex systems stabilized by other species. The theory predicts that the binary water-sulfuric acid system can produce strong new Particle Formation in the free troposphere both through barrier crossing and through kinetic pathways. At cold stratospheric and upper free tropospheric temperatures neutral Formation dominates the binary Particle Formation rates. At midtropospheric temperatures the ion-induced pathway becomes the dominant mechanism. However, even the ion-induced binary mechanism does not produce significant Particle Formation in warm boundary layer conditions, as it requires temperatures below 0°C to take place at atmospheric concentrations. The theory successfully reproduces the characteristics of measured charged and neutral binary Particle Formation in CERN CLOUD3 and CLOUD5 experiments, as discussed in a companion paper.
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Effect of ions on sulfuric acid‐water binary Particle Formation: 1. Theory for kinetic‐ and nucleation‐type Particle Formation and atmospheric implications
Journal of Geophysical Research: Atmospheres, 2016Co-Authors: Joonas Merikanto, Markku Kulmala, Jonathan Duplissy, Anni Maattanen, Henning Henschel, Neil M Donahue, David Brus, Siegfried Schobesberger, Hanna VehkamäkiAbstract:We derive a version of Classical Nucleation Theory normalized by quantum chemical results on sulfuric acid-water hydration to describe neutral and ion-induced Particle Formation in the binary sulfuric acid-water system. The theory is extended to treat the kinetic regime where the nucleation free energy barrier vanishes at high sulfuric acid concentrations or low temperatures. In the kinetic regime Particle Formation rates become proportional to sulfuric acid concentration to second power in the neutral system or first power in the ion-induced system. We derive simple general expressions for the prefactors in kinetic-type and activation-type Particle Formation calculations applicable also to more complex systems stabilized by other species. The theory predicts that the binary water-sulfuric acid system can produce strong new Particle Formation in the free troposphere both through barrier crossing and through kinetic pathways. At cold stratospheric and upper free tropospheric temperatures neutral Formation dominates the binary Particle Formation rates. At midtropospheric temperatures the ion-induced pathway becomes the dominant mechanism. However, even the ion-induced binary mechanism does not produce significant Particle Formation in warm boundary layer conditions, as it requires temperatures below 0°C to take place at atmospheric concentrations. The theory successfully reproduces the characteristics of measured charged and neutral binary Particle Formation in CERN CLOUD3 and CLOUD5 experiments, as discussed in a companion paper.
Shanhu Lee - One of the best experts on this subject based on the ideXlab platform.
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Observations of nighttime new Particle Formation in the troposphere
Journal of Geophysical Research, 2008Co-Authors: Shanhu Lee, Markku Kulmala, D. R. Benson, L.-h. Young, Teresa Campos, David C. Rogers, Tanja Suni, Heikki Junninen, Jorgen B. JensenAbstract:[1] We present atmospheric observations which indicate efficient new Particle Formation during the nighttime in the troposphere under low condensation sinks, in contrast to the current prevailing assumption that aerosol nucleation takes place only during the daytime and typically from sulfuric acid. High concentrations of ultrafine Particles with diameters from 4 to 9 nm (∼1000 cm−3) were measured from the three days of nighttime observations in the upper troposphere during the NSF/NCAR GV Progressive Science Missions. Long-term ground-based observations of charged and neutral clusters and aerosols made in Tumbarumba, Australia, also showed surprisingly high frequency of nighttime new Particle Formation (30%) with low condensation sinks. Nighttime nucleation can be significant for global aerosol load and cloud condensation nuclei productions and thus needs to be included in global climate models. Future studies are required to understand the nighttime nucleation mechanisms.
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When does new Particle Formation not occur in the upper troposphere
Atmospheric Chemistry and Physics, 2007Co-Authors: D. R. Benson, Shanhu Lee, L.-h. Young, D. C. Rogers, Teresa Campos, Jorgen B. JensenAbstract:Recent aircraft studies showed that new Particle Formation is very active in the free troposphere and lower stratosphere. And, these observations lead to a new question: when does new Particle Formation not occur? Here, we provide case studies to show how convection and surface area affect new Particle Formation in the upper troposphere, using the measured aerosol size distributions during the NSF/NCAR GV Progressive Science Missions in December 2005. There were ten research flights, including three days of nighttime experiments, at latitudes from 18 to 52° N and altitudes up to 14 km. About 78% of the total samples showed the new Particle Formation feature with number concentrations of Particles with diameters from 4 to 9 nm, 670±1270 cm ?3 , and the total Particle number concentrations with diameters from 4 to 2000 nm, 920±1470 cm ?3 . Our case studies show that new Particle Formation was closely associated with convection and low surface areas of preexisting aerosol Particles ( ?3 ). On the other hand, for the cases where no new Particle Formation events were observed, air masses usually did not experience a vertical motion and air often originated from either the upper troposphere or lower stratosphere where precursor concentrations are relatively low; in addition, it was also a general trend that non-event cases also had higher surface areas (~16 ?m² cm ?3 ). These observations are consistent with other observations during the Progressive Science Missions (Young et al., 2007). Because of the lower temperatures in this region (T
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Enhanced new Particle Formation observed in the northern midlatitude tropopause region
Journal of Geophysical Research: Atmospheres, 2007Co-Authors: L.-h. Young, Shanhu Lee, D. R. Benson, Jorgen B. Jensen, William M. Montanaro, Laura L. Pan, David C. Rogers, Jeffrey L. Stith, Christopher A. Davis, Teresa CamposAbstract:3960 cm � 3 , were measured during tropopause folds. Our observations show that stratospheric and tropospheric air exchange during tropopause folding events, with a large gradient of temperature and relative humidity, may have enhanced new Particle Formation. Our results are consistent with other modeling predictions showing that nucleation rates are increased with mixing of two air masses with different temperatures and relative humidities. In addition, new Particle Formation events were also associated with vertical motion that may also have brought higher concentrations of water vapor and aerosol precursors (that originate at the ground level) from lower altitudes to higher altitudes where temperatures and surface areas are lower. The average ultrafine Particle concentrations for the regions that were not affected by tropopause folds were also high (>100 cm � 3 ), indicating that nucleation is active in the tropopause region, in general. Our results suggest that atmospheric dynamics, such as stratosphere and troposphere exchange and vertical motion, affect new Particle Formation in this region.
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new Particle Formation observed in the tropical subtropical cirrus clouds
Journal of Geophysical Research, 2004Co-Authors: Shanhu Lee, J C Wilson, D Baumgardner, R L Herman, E M Weinstock, B G Lafleur, Gregory L Kok, B E Anderson, P LawsonAbstract:[1] Previous studies show that new Particle Formation takes place in the outflows of marine stratus and cumulus clouds. Here we show measurements of high concentrations of ultrafine Particles, diameters (Dp) from 4 to 9 nm (N4–9), in interstitial cloud aerosol. These ultrafine Particles indicate that in situ new Particle Formation occurs interstitially in cirrus clouds. Measurements were made at altitudes from 7 to 16 km over Florida with instruments on the WB-57F aircraft during Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiments (CRYSTAL-FACE) in July 2002. Sizeresolved ice crystal Particle concentrations and water vapor concentrations were measured to help identify the presence of cirrus clouds. About 72% of the in-cloud samples showed new Particle Formation events with the average N4–9 of 3.0 10 3 cm 3 , whereas about 56% of the out-of-cloud samples had events with the lower N4–9of 1.3 10 3 cm 3 . The periods during which high N4–9 appeared were often associated with times of increasing ice water content (IWC) and high relative humidity with respect to ice (RHI); however, the measured N4–9was not quantitatively correlated to IWC. The magnitude and frequency of new Particle Formation events seen in cirrus clouds were also higher than those previously observed in the tropical/subtropical upper troposphere in the absence of clouds. These results suggest that cirrus clouds may provide favorable conditions for Particle Formation, such as low temperatures, high RHI, high OH production (due to high water vapor), cloud electricity, and atmospheric convection. At present, however, Particle Formation mechanisms in clouds are unidentified. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and Particles (0345, 4801); 0320 Atmospheric Composition and Structure: Cloud physics and chemistry; 0335 Atmospheric Composition and Structure: Ion chemistry of the atmosphere (2419, 2427); 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 0368 Atmospheric Composition and Structure: Troposphere—constituent transport and chemistry;
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New Particle Formation observed in the tropical//subtropical cirrus clouds
Journal of Geophysical Research, 2004Co-Authors: Shanhu Lee, J C Wilson, D Baumgardner, R L Herman, E M Weinstock, B G Lafleur, Gregory L Kok, B E Anderson, P Lawson, B. BakerAbstract:[1] Previous studies show that new Particle Formation takes place in the outflows of marine stratus and cumulus clouds. Here we show measurements of high concentrations of ultrafine Particles, diameters (Dp) from 4 to 9 nm (N4–9), in interstitial cloud aerosol. These ultrafine Particles indicate that in situ new Particle Formation occurs interstitially in cirrus clouds. Measurements were made at altitudes from 7 to 16 km over Florida with instruments on the WB-57F aircraft during Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiments (CRYSTAL-FACE) in July 2002. Sizeresolved ice crystal Particle concentrations and water vapor concentrations were measured to help identify the presence of cirrus clouds. About 72% of the in-cloud samples showed new Particle Formation events with the average N4–9 of 3.0 10 3 cm 3 , whereas about 56% of the out-of-cloud samples had events with the lower N4–9of 1.3 10 3 cm 3 . The periods during which high N4–9 appeared were often associated with times of increasing ice water content (IWC) and high relative humidity with respect to ice (RHI); however, the measured N4–9was not quantitatively correlated to IWC. The magnitude and frequency of new Particle Formation events seen in cirrus clouds were also higher than those previously observed in the tropical/subtropical upper troposphere in the absence of clouds. These results suggest that cirrus clouds may provide favorable conditions for Particle Formation, such as low temperatures, high RHI, high OH production (due to high water vapor), cloud electricity, and atmospheric convection. At present, however, Particle Formation mechanisms in clouds are unidentified. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and Particles (0345, 4801); 0320 Atmospheric Composition and Structure: Cloud physics and chemistry; 0335 Atmospheric Composition and Structure: Ion chemistry of the atmosphere (2419, 2427); 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 0368 Atmospheric Composition and Structure: Troposphere—constituent transport and chemistry;