The potential for atmospheric mixing processes to enhance the binary nucleation rate

Nilsson, E. Douglas; Kulmala, Markku

doi:10.1029/97jd02629

Cited by 125 publications

(96 citation statements)

References 33 publications

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“…Abrupt air mixing can also take place during rapid uplifting. As shown in previous theoretical predictions (Nilsson and Kulmala., 1998), because nucleation is a non-linear process, when two airmasses mix with each other with different RHI, temperatures, and aerosol precursors, nucleation rates can be much higher than without mixing.…”

Section: Discussionsupporting

confidence: 65%

“…Such differences suggest that the airmass from the strong NPF event underwent a significant extent of vertical motion and rapidly brought higher concentrations of the expected aerosol precursors (e.g., H 2 SO 4 , NH 3 , organic compounds and water vapor, as well as OH and sulfur compounds that can be oxidized to form H 2 SO 4 , including SO 2 ) from lower altitudes to aid in NPF at higher altitudes with lower temperatures. It is also possible that air mixing might occur when the humid and warm air was rapidly uplifted to higher altitudes and mixed with the cold and dry air at the higher altitudes and this case, a steep gradient of temperature and RH took place to enhance nucleation rates because nucleation is a non-linier process as discussed in Nilsson and Kulmala (1998). For the non-event, there was no uplifting present at all.…”

Section: Overallmentioning

confidence: 99%

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The effects of airmass history on new particle formation in the free troposphere: case studies

et al. 2008

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Abstract. Recent aircraft studies showed that new particle formation (NPF) is very active in the free troposphere. And, these observations lead to a new question: when does NPF not occur? Here, we provide case studies to show how different meteorological parameters affect NPF in the upper troposphere, using the aerosol size distributions measured at latitudes from 18 • N-52 • N and altitudes up to 14 km during the NSF/NCAR GV Progressive Science Missions. About 95% of the total samples showed the NPF feature with median number concentrations of particles with diameters from 4 to 9 nm (N 4−9 ), 288±199 cm −3 , and the total particle number concentrations with diameters from 4 to 2000 nm (N 4−2000 ), 500±259 cm −3 . Surface areas were in general very low in the free troposphere, 1.58±0.87 µm 2 cm −3 , which in part explains the high frequency of NPF measured in this region, but there was no distinctive difference in surface area for the NPF and non-NPF cases. Our case studies show that rather airmass history is more important for nucleation in this region. Weak-or non-events did not display uplifting of airmasses. On the other hand, strong NPF events were usually associated with uplifting of airmasses, although there were also NPF cases in which uplift did not occur, consistent with the previous observations (Young et al., 2007). NPF tends to easily occur in the free troposphere because of low surface areas and low temperatures (Carslaw and Kärcher, 2006), but because of the low aerosol precursors in this region, vertical motion (that can bring higher concentrations of aerosol precursors from low altitude source regions to higher altitudes) can play a critical role. Latitude dependence of new particles also shows higher particle concentrations in the midlatitude and subtropics tropopause region than in the tropics, consistent with Hermann et al. (2003).

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Section: Discussionsupporting

confidence: 65%

Section: Overallmentioning

confidence: 99%

The effects of airmass history on new particle formation in the free troposphere: case studies

et al. 2008

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“…He proposed that mixing of air masses can enhance new particle formation, for example, through a local reduction of the saturation water vapor pressure. This is supported by model calculations by Nilsson and Kulmala [1998].…”

Section: Introductionsupporting

confidence: 50%

Particle production in the lowermost stratosphere by convective lifting of the tropopause

Reus¹,

Ström²,

Hoor³

et al. 1999

J. Geophys. Res.

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Abstract. Aircraft measurements of aerosol particles and trace gases were performed in the upper free troposphere and lower stratosphere during the Stratosphere and Troposphere Experiment by Aircraft Measurements (STREAM-96) campaign from Shannon airport, Ireland. During one measurement flight, ultrafine particle number densities up to 10 4 cm -3 (STP) were observed in the lowermost stratosphere. Concurrent with these very high number densities of ultrafine particles, high accumulation mode particle number densities were observed over the same geographical location in the free troposphere, which were attributed to convective transport in the troposphere. The observations suggest that adiabatic cooling of the stratospheric air, as a result of the convective transport in the troposphere that lifted the tropopause and the air in the lowermost stratosphere, was responsible for triggering the formation of new particles.However, also aircraft emissions could have contributed to the enhancement in ultrafine particles. level of the anvil outflow. They explain particle formation in these regions by the high relative humidity and the low preexisting particle number concentration in the air detraining from the cloud. Both conditions are favorable for new particle formation. Similar observations were made by Hegg et al. [1990] near the tops of marine stratiform clouds. They, however, also showed one case where the enhanced Aitken particle layer was separated from the cloud, which they explained by advection of continental air. In this study we present observations of high number densities of ultrafine particles in the lowermost stratosphere, which are proposed to be associated with convective activity in the troposphere. ExperimentDuring the Stratosphere and Troposphere Experiment by Aircraft Measurements (STREAM-96) campaign, six flights were conducted in the free troposphere and lower stratosphere from Shannon airport, Ireland. Instruments for in situ measurements of aerosols and trace gases were installed on a Cessna Citation II twinjet aircraft, operated by the Technical University of Delft, Netherlands. This study focuses on the particle measurements performed on May 22, 1996, over the Atlantic Ocean close to the west coast of Ireland, since this was the only flight where indications for new particle formation were observed in the lower stratosphere. A selection of the measured trace gases is used for the interpretation of the data, namely, ozone, carbon dioxide, and water vapor. On this day a vertical "stack flight," composed of five isobaric flight legs in the free troposphere and lower stratosphere, was carried out between 1400 and 1800 UTC. The flight pattern is shown in Figure 1. The flight section that we focus on covered a region of 6 km in altitude (between 6.5 and 12.5 km altitude), 2 ø in latitude (•220 km) and 1.5 ø in longitude (• 135 km). Horizontal flight tracks were flown at 428, 315, 262, 216, and 178 hPa, respectively.The flight was performed about 6 to 10 hours after the passage of a cold front, whi...

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“…29,30 Other researchers noted that favorable atmospheric conditions, specifically turbulent mixing processes, can enhance nucleation rates by up to several orders of magnitude. [35][36][37][38] Hellmuth and Helmert 38 pointed out that second-order turbulence statistics should be used to represent spatiotemporal variations acting upon the nucleation rate and that there is a strong effect increasing the H 2 SO 4 -H 2 O nucleation rate. On the basis of these findings, a secondorder turbulence closure approach was utilized in the study presented here, and the mesh was chosen to be smallest near the region where the strongest dilution takes place.…”

Section: Resultsmentioning

confidence: 99%

Volatile Nanoparticle Formation and Growth within a Diluting Diesel Car Exhaust

Uhrner

Zallinger

Löwis

et al. 2011

Journal of the Air & Waste Management Association

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A major source of particle number emissions is road traffic. However, scientific knowledge concerning secondary particle formation and growth of ultrafine particles within vehicle exhaust plumes is still very limited. Volatile nanoparticle formation and subsequent growth conditions were analyzed here to gain a better understanding of "real-world" dilution conditions. Coupled computational fluid dynamics and aerosol microphysics models together with measured size distributions within the exhaust plume of a diesel car were used. The impact of soot particles on nucleation, acting as a condensational sink, and the possible role of low-volatile organic components in growth were assessed. A prescribed reduction of soot particle emissions by 2 orders of magnitude (to capture the effect of a diesel particle filter) resulted in concentrations of nucleation-mode particles within the exhaust plume that were approximately 1 order of magnitude larger. Simulations for simplified sulfuric acid-water vapor gas-oil containing nucleation-mode particles show that the largest particle growth is located in a recirculation zone in the wake of the car. Growth of particles within the vehicle exhaust plume up to detectable size depends crucially on the relationship between the mass rate of gaseous precursor emissions and rapid dilution. Chassis dynamometer measurements indicate that emissions of possible hydrocarbon precursors are significantly enhanced under high engine load conditions and high engine speed. On the basis of results obtained for a diesel passenger car, the contributions from light diesel vehicles to the observed abundance of measured nucleation-mode particles near busy roads might be attributable to the impact of two different time scales: (1) a short one within the plume, marked by sufficient precursor emissions and rapid dilution; and (2) a second and comparatively long time scale resulting from the mix of different precursor sources and the impact of atmospheric chemistry.

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The potential for atmospheric mixing processes to enhance the binary nucleation rate

Cited by 125 publications

References 33 publications

The effects of airmass history on new particle formation in the free troposphere: case studies

The effects of airmass history on new particle formation in the free troposphere: case studies

Particle production in the lowermost stratosphere by convective lifting of the tropopause

Volatile Nanoparticle Formation and Growth within a Diluting Diesel Car Exhaust

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