Secondary aerosol formation alters CCN activity in the North China Plain

2021 ◽  
Author(s):  
Jiangchuan Tao ◽  
Ye Kuang ◽  
Nan Ma ◽  
Juan Hong ◽  
Yele Sun ◽  
...  
Keyword(s):  
Particle Size ◽  
North China Plain ◽  
North China ◽  
Particle Mass ◽  
Mixing State ◽  
Particle Size Range ◽  
The North ◽  
The North China Plain ◽  
Aerosol Mixing State ◽  
Ccn Activity

<p>The formation of secondary aerosols (SA, including secondary organic and inorganic aerosols, SOA and SIA) were the dominant sources of aerosol particles in the North China Plain and can result in significant variations of particle size distribution (PNSD) and hygroscopicity. Earlier studies have shown that the mechanism of SA formation can be affected by relative humidity (RH), and thus has different influences on the aerosol hygroscopicity and PNSD under different RH conditions. Based on the measurements of size-resolved particle activation ratio (SPAR), hygroscopicity distribution (GF-PDF), PM<sub>2.5</sub> chemical composition, PNSD, meteorology and gaseous pollutants in a recent field campaign McFAN (Multiphase chemistry experiment in Fogs and Aerosols in the North China Plain) conducted at Gucheng site from November 16<sup>th</sup> to December 16<sup>th</sup> in 2018, the influences of SA formation on CCN activity and CCN number concentration (N<sub>CCN</sub>) calculation at super-saturation of 0.05% under different RH conditions were studied. Measurements showed that during daytime, SA formation could lead to a significant increase in N<sub>CCN</sub> and a strong diurnal variation in CCN activity. During periods with daytime minimum RH exceeding 50% (high RH conditions), SA formation significantly contributed to the particle mass/size changes in wide particle size range of 150 nm to 1000 nm, and led to an increase of N<sub>CCN</sub> in particle size range of 200 nm to 300 nm, while increases in particle mass concentration mainly occurred within particle sizes larger than 300nm. During periods with daytime minimum RH below 30% in (low RH conditions), SA formation mainly contributed to the particle mass/size and N<sub>CCN</sub> changes in particle sizes smaller than 300 nm. As a result, under the same amount SA formation induced mass increase, the increase of N<sub>CCN</sub> was weaker under high RH conditions, while stronger under low RH conditions. Moreover, the diurnal variations of aerosol mixing state (inferred from CCN measurements) due to SA formation was different under different RH conditions. If the variations of the aerosol mixing state were not considered, estimations of N<sub>CCN</sub> would bear significant deviations. By applying aerosol mixing state estimated by number fraction of hygroscopic particles from measurements of particle hygroscopicity or mass fraction of SA from measurements of particle chemical compositions, N<sub>CCN</sub> calculation can be largely improved with relative deviation within 30%. This study improves the understanding of the impact of SA formation on CCN activity and N<sub>CCN</sub> calculation, which is of great significance for improving parameterization of SA formation in aerosol models and CCN calculation in climate models.</p>

scholarly journals Secondary aerosol formation alters CCN activity in the North China Plain

2020 ◽  
Author(s):  
Jiangchuan Tao ◽  
Ye Kuang ◽  
Nan Ma ◽  
Juan Hong ◽  
Yele Sun ◽  
...  
Keyword(s):  
Particle Size ◽  
North China Plain ◽  
North China ◽  
Particle Mass ◽  
Particle Size Range ◽  
The North ◽  
The North China Plain ◽  
Mass Size ◽  
Aerosol Mixing State ◽  
Ccn Activity

Abstract. The formation of secondary aerosols (SA, including secondary organic and inorganic aerosols, SOA and SIA) is the dominant source of aerosol particles in the North China Plain and has a significant impact on the variations of particle size distribution (PNSD) and hygroscopicity. Previous studies have shown that the mechanism of SA formation can be affected by relative humidity (RH), and thus has different influences on the aerosol hygroscopicity and PNSD under different RH conditions. Based on the measurements of size-resolved particle activation ratio (SPAR), hygroscopicity distribution (GF-PDF), PM2.5 chemical composition, PNSD, meteorology and gaseous pollutants in a recent field campaign McFAN (Multiphase chemistry experiment in Fogs and Aerosols in the North China Plain) conducted at Gucheng site from 16th November to 16th December in 2018, the influences of SA formation on CCN activity and CCN number concentration (NCCN) calculation under different RH conditions were studied. Measurements showed that during daytime the SA formation can lead to a significant increase of NCCN and a strong diurnal variation of CCN activity. During periods with minimum RH higher than 50 % in daytime (high RH conditions), SA formation significantly contributed to the particle mass/size changes in wide particle size range of 150 nm to 1000 nm, and lead to the increase of NCCN in particle size range of 200 nm to 300 nm while increase of particle mass concentration mainly in particle size larger than 300 nm. During periods with minimum RH lower than 30 % in daytime (low RH conditions), SA formation mainly contributed to the particle mass/size changes in particle size smaller than 300 nm and so did the increases of both NCCN and particle mass concentration. As a result, upon the same amount of mass increase through SA formation, the increase of NCCN is weaker under high RH conditions while stronger under low RH conditions. Moreover, the diurnal variations of aerosol mixing state (inferred from CCN measurements) due to SA formation was different under different RH conditions, which contributed one of the largest uncertainties in NCCN predictions. By applying aerosol mixing state estimated by number fraction of hygroscopic particles from measurements of particle hygroscopicity or mass fraction of SA from measurements of particle chemical compositions, the NCCN prediction was largely improved with relative deviations smaller than 30 %. This study highlights the impact of SA formation on CCN activity and NCCN calculation, which is of great significance for improving parameterization of SA formation in chemical-transport models and CCN predictions in climate models.

Mass-based mixing state of black carbon measured by a tandem CPMA-SP2 system in wintertime in the North China Plain

2020 ◽  
Author(s):  
Shaowen Zhu ◽  
Nan Ma ◽  
Xihao Pan ◽  
Wenlin Dong ◽  
Jiangchuan Tao ◽  
...  
Keyword(s):  
Black Carbon ◽  
North China Plain ◽  
North China ◽  
Data Retrieval ◽  
Particle Mass ◽  
Radiative Properties ◽  
Mass Analyzer ◽  
Mixing State ◽  
The North ◽  
The North China Plain

<p>Black carbon (BC) is the most important light absorbing component in the atmosphere and has significant impacts on the climate, environment and public health. Its effects depend not only on its spatial-temporal distribution, but also on its physico-chemical characteristics. Mixing state is one of the most important properties of BC and strongly determines its hygroscopicity and radiative properties. During an intensive field campaign conducted in the North China Plain in winter 2018, mass-based mixing state of BC-containing particles were online measured with a Centrifugal Particle Mass Analyzer and Single Particle Soot Photometer (CPMA-SP2) tandem system. This technique directly provides the mass ratio of non-refractory coating matter to BC core (M<sub>R</sub>) in individual particles and does not require to assume the density, morphology and refractive index of BC core and coating in data retrieval, therefore has lower uncertainly compared with leading-edge fit technique. In our measurement, the mean number fraction of uncoated (M<sub>R</sub>=0), thin coated (0<M<sub>R</sub><3) and thick coated (M<sub>R</sub>≥3) BC-containing particle during the campaign were respectively ~10%, ~35% and ~55%, indicating the strong aging process of BC-containing particle in the North China Plain. The median value of M<sub>R</sub> was much higher in polluted days than clean days, for example, the median value of M<sub>R</sub> with a particle mass of 8.56 fg (~220 nm in diameter) for polluted and clean days were ~3.2 and ~1.6, respectively. The mixing state of BC-containing particles obtained by different methods were also compared and evaluated.</p>

scholarly journals Secondary aerosol formation alters CCN activity in the North China Plain

2021 ◽  
Vol 21 (9) ◽  
pp. 7409-7427
Author(s):  
Jiangchuan Tao ◽  
Ye Kuang ◽  
Nan Ma ◽  
Juan Hong ◽  
Yele Sun ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Size Range ◽  
Particle Mass ◽  
Rural Site ◽  
Formation Mechanisms ◽  
The North ◽  
The North China Plain ◽  
The Impact ◽  
Ccn Activity

Abstract. Secondary aerosols (SAs, including secondary organic and inorganic aerosols, SOAs and SIAs) are predominant components of aerosol particles in the North China Plain (NCP), and their formation has significant impacts on the evolution of particle size distribution (PNSD) and hygroscopicity. Previous studies have shown that distinct SA formation mechanisms can dominate under different relative humidity (RH). This would lead to different influences of SA formation on the aerosol hygroscopicity and PNSD under different RH conditions. Based on the measurements of size-resolved particle activation ratio (SPAR), hygroscopicity distribution (GF-PDF), PM2.5 chemical composition, PNSD, meteorology and gaseous pollutants in a recent field campaign, McFAN (Multiphase chemistry experiment in Fogs and Aerosols in the North China Plain), conducted during the autumn–winter transition period in 2018 at a polluted rural site in the NCP, the influences of SA formation on cloud condensation nuclei (CCN) activity and CCN number concentration (NCCN) calculation under different RH conditions were studied. Results suggest that during daytime, SA formation could lead to a significant increase in NCCN and a strong diurnal variation in SPAR at supersaturations lower than 0.07 %. During periods with daytime minimum RH exceeding 50 % (high RH conditions), SA formation significantly contributed to the particle mass and size changes in a broad size range of 150 to 1000 nm, leading to NCCN (0.05 %) increases within the size range of 200 to 500 nm and mass concentration growth mainly for particles larger than 300 nm. During periods with daytime minimum RH below 30 % (low RH conditions), SA formation mainly contributed to the particle mass and size and NCCN changes for particles smaller than 300 nm. As a result, under the same amount of mass increase induced by SA formation, the increase of NCCN (0.05 %) was stronger under low RH conditions and weaker under high RH conditions. Moreover, the diurnal variations of the SPAR parameter (inferred from CCN measurements) due to SA formation varied with RH conditions, which was one of the largest uncertainties within NCCN predictions. After considering the SPAR parameter (estimated through the number fraction of hygroscopic particles or mass fraction of SA), the relative deviation of NCCN (0.05 %) predictions was reduced to within 30 %. This study highlights the impact of SA formation on CCN activity and NCCN calculation and provides guidance for future improvements of CCN predictions in chemical-transport models and climate models.

scholarly journals Influence of biomass burning on mixing state of sub-micron aerosol particles in the North China Plain

2017 ◽  
Vol 164 ◽  
pp. 259-269 ◽  
Author(s):  
Simonas Kecorius ◽  
Nan Ma ◽  
Monique Teich ◽  
Dominik van Pinxteren ◽  
Shenglan Zhang ◽  
...  
Keyword(s):  
Biomass Burning ◽  
North China Plain ◽  
North China ◽  
Aerosol Particles ◽  
Mixing State ◽  
The North ◽  
The North China Plain

Influence of size and mixing state on the wet scavenging of black carbon aerosol in the North China Plain

2020 ◽  
Author(s):  
Xihao Pan ◽  
Nan Ma ◽  
Yaqing Zhou ◽  
Shaowen Zhu ◽  
Long Peng ◽  
...  
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
North China Plain ◽  
North China ◽  
Mixing State ◽  
Radiation Fog ◽  
The North ◽  
The North China Plain ◽  
Positive Direct ◽  
Scavenging Efficiency

<p>Black carbon (BC) is the most important light-absorbing species in the atmosphere and has a strong positive direct radiative forcing. In-cloud scavenging is the major way to wash out BC from the atmosphere. Understanding the connection between its physico-chemical properties and scavenging efficiency is therefore a key to evaluate its lifetime, atmospheric burden and spatial distribution. During an intensive field campaign conducted in the North China Plain in 2019, a ground-based counterflow virtual impactor was utilized to separate fog droplets in radiation fog events. BC mass and mixing state of fog droplet residues were online measured with a single particle soot photometer (SP2). In a strong radiation fog event with visibility of about 50 m, more than 20% fog droplets are found to contain a BC core. BC scavenging efficiency is found to be strongly determined by its diameter and mixing state. Driven by different mechanisms, higher scavenging efficiencies up to 10% are observed for larger and smaller BC particles, and the minimum efficiency is found at BC diameter of 120 nm. For large core (>120 nm) BC-containing particles, the scavenging efficiency increases significantly with coating thickness (CT), from about 10% for CT<100 nm to 80% for CT>300 nm. Chemical composition may also be a key parameter influencing the scavenging of BC. Based on the observation of 3 fog events, parameterizations of BC scavenging efficiency are also given in this study.</p>

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