New particle formation events persistently reduce cloud droplets in boundary layer clouds

2020 ◽  
Author(s):  
David Patoulias ◽  
Kalliopi Florou ◽  
Spyros N. Pandis ◽  
Athanasios Nenes
Keyword(s):  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Particle Formation ◽  
New Particle Formation ◽  
Cloud Droplets ◽  
Convective Clouds ◽  
Boundary Layer Clouds ◽  
Stratiform Clouds ◽  
Local Warming ◽  
Climate Cooling

<p>Α considerable fraction of cloud condensation nuclei (CCN) originates from new particle formation (NPF). Because of this, NPF events themselves are thought to also increase CCN and cloud droplet number (CDN) and contribute to climate cooling. High resolution state-of-the-art simulations over Europe however portray a different view: radiatively important stratiform clouds influenced by NPF events experience a systematic and substantial decrease in droplet number during and after nucleation events. The drop in CDN occurs because particles present prior to the NPF experiences slower growth during and after each event (as the condensable material is consumed by the growth of the NPF particles that do not typically activate), leading to fewer CCN at the low supersaturation levels characteristic of stratiform clouds (~0.1%). Convective clouds, however, tend to experience a modest increase in cloud droplet number – consistent with established views on the NPF-cloud link. Our results are corroborated by published observational evidence and all together reshape our conceptual understanding of NPF events on clouds, where droplets in stratiform clouds tend to be reduced (leading to local warming from reductions in cloud albedo) but enhance in convection. Combined, these effects could bear important impacts on cloud structure following NPF events.</p>

scholarly journals Atmospheric new particle formation as source of CCN in the Eastern Mediterranean marine boundary layer

2015 ◽  
Vol 15 (7) ◽  
pp. 11143-11178 ◽  
Author(s):  
N. Kalivitis ◽  
V.-M. Kerminen ◽  
G. Kouvarakis ◽  
I. Stavroulas ◽  
A. Bougiatioti ◽  
...  
Keyword(s):  
Organic Material ◽  
Marine Boundary Layer ◽  
Size Range ◽  
Eastern Mediterranean ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Particle Formation ◽  
New Particle Formation ◽  
Multiple Sources ◽  
Marine Air

Abstract. While Cloud Condensation Nuclei (CCN) production associated with atmospheric new particle formation (NPF) is thought to be frequent throughout the continental boundary layers, few studies on this phenomenon in marine air exist. Here, based on simultaneous measurement of particle number size distributions, CCN properties and aerosol chemical composition, we present the first direct evidence on CCN production resulting from NPF in the Eastern Mediterranean atmosphere. We show that condensation of both gaseous sulfuric acid and organic compounds from multiple sources leads to the rapid growth of nucleated particles to CCN sizes in this environment during the summertime. Sub-100 nm particles were found to be substantially less hygroscopic than larger particles during the period with active NPF and growth (0.2–0.4 lower κ between the 60 and 120 nm particles), probably due to enrichment of organic material in the sub-100 nm size range. The aerosol hygroscopicity tended to be at minimum just before the noon and at maximum in afternoon, which was very likely due to the higher sulfate to organic ratios and higher degree of oxidation of the organic material during the afternoon. Simultaneously to the formation of new particles during daytime, particles formed in the previous day or even earlier were growing into the size range relevant to cloud droplet activation, and the particles formed in the atmosphere were possibly mixed with long-range transported particles.

scholarly journals Evaluation of the contribution of new particle formation to cloud droplet in urban atmosphere

2021 ◽  
Author(s):  
Sihui Jiang ◽  
Fang Zhang ◽  
Jingye Ren ◽  
Lu Chen ◽  
Xing Yan ◽  
...  
Keyword(s):  
Water Vapor ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Cloud Droplet ◽  
Particle Formation ◽  
Urban Atmosphere ◽  
Primary Sources ◽  
New Particle Formation ◽  
Multiple Sources ◽  
Considerable Impact

Abstract. New particle formation (NPF) is a large source of cloud condensation nuclei (CCN) and cloud droplet in the troposphere. In this study, we quantified the contribution of NPF to cloud droplet number concentration (CDNC, or Nd) at typical updraft velocities (V) in clouds using a field campaign data of aerosol number size distribution and chemical composition observed on May 25–June 18, 2017 in urban Beijing. We show that the NPF drives the variations of CCN and cloud droplet and increases Nd by 30–33 % at V = 0.3–3 m s−1 in urban atmosphere. A markedly reduction in Nd is observed due to water vapor competition with consideration of actual environmental updraft velocity, decreasing by 11.8 ± 5.0 % at V = 3 m s−1 and 19.0 ± 4.5 % at V = 0.3 m s−1 compared to that from a prescribed supersaturation. The effect of water vapor competition becomes smaller at larger V that can provide more sufficient water vapor. Essentially, water vapor competition led to the reduction in Nd by decreasing the environmental maximum supersaturation (Smax) for the activation of aerosol particles. It is shown that Smax was decreased by 14.5–11.7 % for V = 0.3–3 m s−1. Particularly, the largest suppression of cloud droplet formation due to the water vapor competition is presented at extremely high aerosol particle number concentrations. As a result, although a larger increase of CCN-size particles by NPF event is derived on clean NPF day when pre-existing background aerosol particles are very low, there is no large discrepancy in the enhancement of Nd by NPF between the clean and polluted NPF day. We finally show a considerable impact of the primary sources when evaluating the NPF contribution to cloud droplet based on a case study. Our study highlights the importance of fully consideration of both the environmental meteorological conditions and multiple sources (i.e. secondary and primary) to evaluate the NPF effect on clouds and the associated climate effects in polluted regions.

scholarly journals Atmospheric new particle formation as a source of CCN in the eastern Mediterranean marine boundary layer

2015 ◽  
Vol 15 (16) ◽  
pp. 9203-9215 ◽  
Author(s):  
N. Kalivitis ◽  
V.-M. Kerminen ◽  
G. Kouvarakis ◽  
I. Stavroulas ◽  
A. Bougiatioti ◽  
...  
Keyword(s):  
Organic Material ◽  
Marine Boundary Layer ◽  
Size Range ◽  
Eastern Mediterranean ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Particle Formation ◽  
New Particle Formation ◽  
Multiple Sources ◽  
Marine Air

Abstract. While cloud condensation nuclei (CCN) production associated with atmospheric new particle formation (NPF) is thought to be frequent throughout the continental boundary layers, few studies on this phenomenon in marine air exist. Here, based on simultaneous measurement of particle number size distributions, CCN properties and aerosol chemical composition, we present the first direct evidence on CCN production resulting from NPF in the eastern Mediterranean atmosphere. We show that condensation of both gaseous sulfuric acid and organic compounds from multiple sources leads to the rapid growth of nucleated particles to CCN sizes in this environment during the summertime. Sub-100 nm particles were found to be substantially less hygroscopic than larger particles during the period with active NPF and growth (the value of κ was lower by 0.2–0.4 for 60 nm particles compared with 120 nm particles), probably due to enrichment of organic material in the sub-100 nm size range. The aerosol hygroscopicity tended to be at minimum just before the noon and at maximum in the afternoon, which was very likely due to the higher sulfate-to-organic ratios and higher degree of oxidation of the organic material during the afternoon. Simultaneous with the formation of new particles during daytime, particles formed during the previous day or even earlier were growing into the size range relevant to cloud droplet activation, and the particles formed in the atmosphere were possibly mixed with long-range-transported particles.

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 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 Regional new particle formation as modulators of cloud condensation nuclei and cloud droplet number in the eastern Mediterranean

2019 ◽  
Vol 19 (9) ◽  
pp. 6185-6203 ◽  
Author(s):  
Panayiotis Kalkavouras ◽  
Aikaterini Bougiatioti ◽  
Nikos Kalivitis ◽  
Iasonas Stavroulas ◽  
Maria Tombrou ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Particle Formation ◽  
Cloud Formation ◽  
New Particle Formation ◽  
Condensation Nuclei ◽  
Low Cloud ◽  
Condensational Growth ◽  
The Impact

Abstract. A significant fraction of atmospheric particles that serve as cloud condensation nuclei (CCN) are thought to originate from the condensational growth of new particle formation (NPF) from the gas phase. Here, 7 years of continuous aerosol and meteorological measurements (June 2008 to May 2015) at a remote background site of the eastern Mediterranean were recorded and analyzed to assess the impact of NPF (of 162 episodes identified) on CCN and cloud droplet number concentration (CDNC) formation in the region. A new metric is introduced to quantitatively determine the initiation and duration of the influence of NPF on the CCN spectrum. NPF days were found to increase CCN concentrations (from 0.10 % to 1.00 % supersaturation) between 29 % and 77 %. Enhanced CCN concentrations from NPF are mostly observed, as expected, under low preexisting particle concentrations and occur in the afternoon, relatively later in the winter and autumn than in the summer. Potential impacts of NPF on cloud formation were quantified by introducing the observed aerosol size distributions and chemical composition into an established cloud droplet parameterization. We find that the supersaturations that develop are very low (ranging between 0.03 % and 0.27 %) for typical boundary layer dynamics (σw ∼0.3 m s−1) and NPF is found to enhance CDNC by a modest 13 %. This considerable contrast between CCN and CDNC response is in part from the different supersaturation levels considered, but also because supersaturation drops from increasing CCN because of water vapor competition effects during the process of droplet formation. The low cloud supersaturation further delays the appearance of NPF impacts on CDNC to clouds formed in the late evening and nighttime – which has important implications for the extent and types of indirect effects induced by NPF events. An analysis based on CCN concentrations using prescribed supersaturation can provide very different, even misleading, conclusions and should therefore be avoided. The proposed approach here offers a simple, yet highly effective way for a more realistic impact assessment of NPF events on cloud formation.

scholarly journals Seasonal variation of CCN concentrations and aerosol activation properties in boreal forest

2011 ◽  
Vol 11 (24) ◽  
pp. 13269-13285 ◽  
Author(s):  
S.-L. Sihto ◽  
J. Mikkilä ◽  
J. Vanhanen ◽  
M. Ehn ◽  
L. Liao ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Cloud Condensation Nuclei ◽  
Critical Diameter ◽  
Cloud Droplet ◽  
Particle Formation ◽  
Distribution Data ◽  
New Particle Formation ◽  
Hygroscopic Growth ◽  
Average Value ◽  
Kohler Theory

Abstract. As a part of EUCAARI activities, the annual cycle of cloud condensation nuclei (CCN) concentrations and critical diameter for cloud droplet activation as a function of supersaturation were measured using a CCN counter and a HTDMA (hygroscopicity tandem differential mobility analyzer) at SMEAR II station, Hyytiälä, Finland. The critical diameters for CCN activation were estimated from (i) the measured CCN concentration and particle size distribution data, and (ii) the hygroscopic growth factors by applying κ-Köhler theory, in both cases assuming an internally mixed aerosol. The critical diameters derived by these two methods were in good agreement with each other. The effect of new particle formation on the diurnal variation of CCN concentration and critical diameters was studied. New particle formation was observed to increase the CCN concentrations by 70–110%, depending on the supersaturation level. The average value for the κ-parameter determined from hygroscopicity measurements was κ = 0.18 and it predicted well the CCN activation in boreal forest conditions in Hyytiälä. The derived critical diameters and κ-parameter confirm earlier findings with other methods, that aerosol particles at CCN sizes in Hyytiälä are mostly organic, but contain also more hygrosopic, probably inorganic salts like ammonium sulphate, making the particles more CCN active than pure secondary organic aerosol.

scholarly journals Evaluation of the contribution of new particle formation to cloud droplet number concentration in the urban atmosphere

2021 ◽  
Vol 21 (18) ◽  
pp. 14293-14308
Author(s):  
Sihui Jiang ◽  
Fang Zhang ◽  
Jingye Ren ◽  
Lu Chen ◽  
Xing Yan ◽  
...  
Keyword(s):  
Water Vapor ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Particle Formation ◽  
Number Concentration ◽  
Urban Atmosphere ◽  
New Particle Formation ◽  
High Background ◽  
Effect Of Water ◽  
Cloud Droplet Number Concentration

Abstract. The effect of new particle formation (NPF) on cloud condensation nuclei (CCN) varies widely in diverse environments. CCN or cloud droplets from NPF sources remain highly uncertain in the urban atmosphere; they are greatly affected by the high background aerosols and frequent local emissions. In this study, we quantified the effect of NPF on cloud droplet number concentration (CDNC, or Nd) at typical updraft velocities (V) in clouds based on field observations on 25 May–18 June 2017 in urban Beijing. We show that NPF increases the Nd by 32 %–40 % at V=0.3–3 m s−1 during the studied period. The Nd is reduced by 11.8 ± 5.0 % at V=3 m s−1 and 19.0 ± 4.5 % at V=0.3 m s−1 compared to that calculated from constant supersaturations due to the water vapor competition effect, which suppresses the cloud droplet formation by decreasing the environmental maximum supersaturation (Smax). The effect of water vapor competition becomes smaller at larger V that can provide more sufficient water vapor. However, under extremely high aerosol particle number concentrations, the effect of water vapor competition becomes more pronounced. As a result, although a larger increase of CCN-sized particles by NPF events is derived on clean NPF days when the number concentration of preexisting background aerosol particles is very low, no large discrepancy is presented in the enhancement of Nd by NPF between clean and polluted NPF days. We finally reveal a considerable impact of the primary sources on the evaluation of the contribution of NPF to CCN number concentration (NCCN) and Nd based on a case study. Our study highlights the importance of full consideration of both the environmental meteorological conditions and multiple sources (i.e., secondary and primary) to evaluate the effect of NPF on clouds and the associated climate effects in polluted regions.

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

2011 ◽  
Vol 11 (9) ◽  
pp. 25709-25750 ◽  
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.

Sign in / Sign up

Export Citation Format

Share Document