scholarly journals Supplementary material to "Regional New Particle Formation as Modulators of Cloud Condensation Nuclei and Cloud Droplet Number in the Eastern Mediterranean"

2018 ◽  
Author(s):  
Panayiotis Kalkavouras ◽  
Aikaterini Bougiatioti ◽  
Nikos Kalivitis ◽  
Maria Tombrou ◽  
Athanasios Nenes ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Particle Formation ◽  
New Particle Formation ◽  
Condensation Nuclei ◽  
Supplementary Material

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 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 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 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.

A large source of cloud condensation nuclei from new particle formation in the tropics

Nature ◽  
2019 ◽  
Vol 574 (7778) ◽  
pp. 399-403 ◽  
Author(s):  
Christina J. Williamson ◽  
Agnieszka Kupc ◽  
Duncan Axisa ◽  
Kelsey R. Bilsback ◽  
ThaoPaul Bui ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Particle Formation ◽  
New Particle Formation ◽  
Condensation Nuclei ◽  
Large Source ◽  
The Tropics

scholarly journals Hygroscopic properties and cloud condensation nuclei activity of atmospheric aerosols under the influences of Asian continental outflow and new particle formation at a coastal site in eastern Asia

2020 ◽  
Vol 20 (10) ◽  
pp. 5911-5922 ◽  
Author(s):  
Hing Cho Cheung ◽  
Charles Chung-Kuang Chou ◽  
Celine Siu Lan Lee ◽  
Wei-Chen Kuo ◽  
Shuenn-Chin Chang
Keyword(s):  
Chemical Composition ◽  
Cloud Condensation Nuclei ◽  
Particle Formation ◽  
Number Concentration ◽  
Pollution Sources ◽  
New Particle Formation ◽  
Condensation Nuclei ◽  
Air Masses ◽  
Hygroscopic Properties ◽  
Aerosol Hygroscopicity

Abstract. The chemical composition of fine particulate matter (PM2.5), the size distribution and number concentration of aerosol particles (NCN), and the number concentration of cloud condensation nuclei (NCCN) were measured at the northern tip of Taiwan during an intensive observation experiment from April 2017 to March 2018. The parameters of aerosol hygroscopicity (i.e., activation ratio, activation diameter and kappa of CCN) were retrieved from the measurements. Significant variations were found in the hygroscopicity of aerosols (kappa – κ – of 0.18–0.56, for water vapor supersaturation – SS – of 0.12 %–0.80 %), which were subject to various pollution sources, including aged air pollutants originating in eastern and northern China and transported by the Asian continental outflows and fresh particles emitted from local sources and distributed by land–sea breeze circulations as well as produced by processes of new particle formation (NPF). Cluster analysis was applied to the back trajectories of air masses to investigate their respective source regions. The results showed that aerosols associated with Asian continental outflows were characterized by lower NCN and NCCN values and by higher kappa values of CCN, whereas higher NCN and NCCN values with lower kappa values of CCN were observed in the aerosols associated with local air masses. Besides, it was revealed that the kappa value of CCN exhibited a decrease during the early stage of an event of new particle formation, which turned to an increasing trend over the later period. The distinct features in the hygroscopicity of aerosols were found to be consistent with the characteristics in the chemical composition of PM2.5. This study has depicted a clear seasonal characteristic of hygroscopicity and CCN activity under the influence of a complex mixture of pollutants from different regional and/or local pollution sources. Nevertheless, the mixing state and chemical composition of the aerosols critically influence the aerosol hygroscopicity, and further investigations are necessary to elucidate the atmospheric processing involved in the CCN activation in coastal areas.

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