scholarly journals Coastal and open ocean aerosol characteristics: investigating the representativeness of coastal aerosol sampling over the North-East Atlantic Ocean

2008 ◽  
Vol 8 (6) ◽  
pp. 19035-19062 ◽  
Author(s):  
M. Rinaldi ◽  
M. C. Facchini ◽  
S. Decesari ◽  
C. Carbone ◽  
E. Finessi ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Atlantic Ocean ◽  
Size Distribution ◽  
Surf Zone ◽  
Open Ocean ◽  
Water Soluble ◽  
Research Station ◽  
Coastal Site ◽  
Physical And Chemical ◽  
Aerosol Properties

Abstract. In order to achieve a better understanding of the modifications of the physical and chemical properties of marine aerosol particles during transport from offshore to the coast, size distribution and chemical composition were measured concurrently in clean air masses over the open North Atlantic Ocean and at an Irish coastal site. Open ocean sampling was performed on board the oceanographic vessel Celtic Explorer sailing 100–300 km off the Irish west coast, while coastal measurements were performed at the Mace Head GAW station. The experiment took place between 11 June and 6 July 2006, during the period of phytoplankton bloom. The number size distribution and size-resolved chemical composition of coastal and open ocean samples were very similar, indicating homogeneous physical and chemical aerosol properties over a wide region in the marine boundary layer. The results also show that submicron chemical and physical aerosol properties measured at the coastal Mace Head Atmospheric Research Station were not unduly influenced by coastal artefacts and are thus representative of open water properties. Greater differences between the coastal site and the open ocean were observed for the aerosol supermicron sea spray components; this could be due to a variety of reasons, ranging from higher local wind speeds at the coastal site over the comparison period, to differences in sampling heights and increased local surf-zone production. Evidence of ageing processes was observed: at the costal site the ratio between non-sea-salt sulphate and methanesulphonic acid was higher, and the aerosol water soluble organic compounds were more oxidized than in the open ocean.

scholarly journals Aerosol properties associated with air masses arriving into the North East Atlantic during the 2008 Mace Head EUCAARI intensive observing period: an overview

2010 ◽  
Vol 10 (17) ◽  
pp. 8413-8435 ◽  
Author(s):  
M. Dall'Osto ◽  
D. Ceburnis ◽  
G. Martucci ◽  
J. Bialek ◽  
R. Dupuy ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Cloud Microphysics ◽  
Water Soluble ◽  
Research Station ◽  
Hygroscopic Growth ◽  
Condensation Nuclei ◽  
Air Masses ◽  
North East ◽  
Marine Air ◽  
Aerosol Properties

Abstract. As part of the EUCAARI Intensive Observing Period, a 4-week campaign to measure aerosol physical, chemical and optical properties, atmospheric structure, and cloud microphysics was conducted from mid-May to mid-June, 2008 at the Mace Head Atmospheric Research Station, located at the interface of Western Europe and the N. E. Atlantic and centered on the west Irish coastline. During the campaign, continental air masses comprising both young and aged continental plumes were encountered, along with polar, Arctic and tropical air masses. Polluted-continental aerosol concentrations were of the order of 3000 cm−3, while background marine air aerosol concentrations were between 400–600 cm−3. The highest marine air concentrations occurred in polar air masses in which a 15 nm nucleation mode, with concentration of 1100 cm−3, was observed and attributed to open ocean particle formation. Continental air submicron chemical composition (excluding refractory sea salt) was dominated by organic matter, closely followed by sulphate mass. Although the concentrations and size distribution spectral shape were almost identical for the young and aged continental cases, hygroscopic growth factors (GF) and cloud condensation nuclei (CCN) to total condensation nuclei (CN) concentration ratios were significantly less in the younger pollution plume, indicating a more oxidized organic component to the aged continental plume. The difference in chemical composition and hygroscopic growth factor appear to result in a 40–50% impact on aerosol scattering coefficients and Aerosol Optical Depth, despite almost identical aerosol microphysical properties in both cases, with the higher values been recorded for the more aged case. For the CCN/CN ratio, the highest ratios were seen in the more age plume. In marine air, sulphate mass dominated the sub-micron component, followed by water soluble organic carbon, which, in turn, was dominated by methanesulphonic acid (MSA). Sulphate concentrations were highest in marine tropical air – even higher than in continental air. MSA was present at twice the concentrations of previously-reported concentrations at the same location and the same season. Both continental and marine air exhibited aerosol GFs significantly less than ammonium sulphate aerosol pointing to a significant organic contribution to all air mass aerosol properties.

scholarly journals Aerosol properties associated with air masses arriving into the North East Atlantic during the 2008 Mace Head EUCAARI intensive observing period: an overview

2009 ◽  
Vol 9 (6) ◽  
pp. 26265-26328 ◽  
Author(s):  
M. Dall'Osto ◽  
D. Ceburnis ◽  
G. Martucci ◽  
J. Bialek ◽  
R. Dupuy ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Cloud Microphysics ◽  
Sea Salt ◽  
Water Soluble ◽  
Research Station ◽  
Hygroscopic Growth ◽  
Condensation Nuclei ◽  
Air Masses ◽  
Marine Air ◽  
Aerosol Properties

Abstract. As part of the EUCAARI Intensive Observing Period, a 4-week campaign to measure aerosol physical, chemical and optical properties, atmospheric structure, and cloud microphysics was conducted from mid-May to mid-June 2008 at the Mace Head Atmospheric Research Station, located at the interface of Western Europe and the NE Atlantic and centered on the west Irish coastline. During the campaign, continental air masses comprising both young and aged continental plumes were encountered, along with polar, Arctic and tropical air masses. Polluted-continental aerosol concentrations were of the order of 3000 cm−3, while background marine air aerosol concentrations were between 400–600 cm−3. The highest marine air concentrations occurred in polar air masses in which a 15 nm nucleation mode, with concentration of 1100 cm−3, was observed and attributed to open ocean particle formation. Black carbon concentrations in polluted air were between 300–400 ng m−3, and in clean marine air were less than 50 ng m−3. Continental air submicron chemical composition (excluding refractory sea salt) was dominated by organic matter, closely followed by sulphate mass. Although the concentrations and size distribution spectral shape were almost identical for the young and aged continental cases, hygroscopic growth factors (GF) and cloud condensation nuclei (CCN) to total condensation nuclei (CN) concentration ratios were significantly less in the younger pollution plume, indicating a more oxidized organic component to the aged continental plume. The difference in chemical composition and hygroscopic growth factor appear to result in a 40–50% impact on aerosol scattering coefficients and Aerosol Optical Depth, despite almost identical aerosol microphysical properties in both cases, with the higher values been recorded for the more aged case. For the CCN/CN ratio, the highest ratios were seen in the more age plume. In marine air, sulphate mass dominated the sub-micron component, followed by water soluble organic carbon, which, in turn, was dominated by methanesulphonic acid (MSA). Sulphate concentrations were highest in marine tropical air – even higher than in continental air. MSA was present at twice the concentrations of previously-reported concentrations at the same location and the same season. Both continental and marine air exhibited aerosol GFs significantly less than ammonium sulphate and even less in terms of sea salt aerosol pointing to a significant organic contribution to all air mass aerosol properties.

scholarly journals Impact of long-range transport over the Atlantic Ocean on Saharan dust optical and microphysical properties

2017 ◽  
Author(s):  
Cristian Velasco-Merino ◽  
David Mateos ◽  
Carlos Toledano ◽  
Joseph M. Prospero ◽  
Jack Molinie ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Size Distribution ◽  
Mineral Dust ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
West African ◽  
Asymmetry Factor ◽  
Caribbean Basin ◽  
Air Mass ◽  
Aerosol Properties

Abstract. Mineral dust aerosol can be a major driver of aerosol climatology in regions distant from the sources. This study addresses the change of columnar aerosol properties when mineral dust arrives to the Caribbean Basin after transport from Africa over the Atlantic Ocean. We use data from NASA Aerosol Robotic Network (AERONET) sites in five Caribbean and two West African sites to characterize changes in aerosol properties: aerosol optical depth, size distribution, single scattering albedo, and refractive indexes. After obtaining local aerosol climatology in each area, the air mass connections between West Africa and Caribbean Basin have been investigated by means of air mass back trajectories. Over the period 1996–2014 we identify 3174 connection days, on average, 167 connection days per year. Among these, 1162 pairs of data present aerosol data in Caribbean sites with corresponding aerosol observations in Western Africa sites ~5–7 days before. Of these 1162 days, 484 meet the criteria to be characterized as mineral dust outbreaks. Based on these days we observe the following changes in aerosol-related properties in transiting the Atlantic: AOD decreases about 0.16 or −30 %; the volume particle size distribution shape shows no changes; single scattering albedo, refractive indexes, and asymmetry factor remain unchanged; the difference in the effective radius in West African area with respect to Caribbean Basin is between 0 and +0.3 µm; and half of the analyzed cases present predominance of non-spherical particles in both areas.

scholarly journals Chemical composition and source apportionment of atmospheric aerosols on the Namibian coast

2020 ◽  
Vol 20 (24) ◽  
pp. 15811-15833
Author(s):  
Danitza Klopper ◽  
Paola Formenti ◽  
Andreas Namwoonde ◽  
Mathieu Cazaunau ◽  
Servanne Chevaillier ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Biomass Burning ◽  
Mineral Dust ◽  
Open Ocean ◽  
Sea Salt ◽  
Water Soluble ◽  
Marine Phytoplankton ◽  
Fugitive Dust ◽  
The South ◽  
North West

Abstract. The chemical composition of aerosols is of particular importance to assess their interactions with radiation, clouds and trace gases in the atmosphere and consequently their effects on air quality and the regional climate. In this study, we present the results of the first long-term dataset of the aerosol chemical composition at an observatory on the coast of Namibia, facing the south-eastern Atlantic Ocean. Aerosol samples in the mass fraction of particles smaller than 10 µm in aerodynamic diameter (PM10) were collected during 26 weeks between 2016 and 2017 at the ground-based Henties Bay Aerosol Observatory (HBAO; 22∘6′ S, 14∘30′ E; 30 m above mean sea level). The resulting 385 filter samples were analysed by X-ray fluorescence and ion chromatography for 24 inorganic elements and 15 water-soluble ions. Statistical analysis by positive matrix factorisation (PMF) identified five major components, sea salt (mass concentration: 74.7±1.9 %), mineral dust (15.7±1.4 %,), ammonium neutralised (6.1±0.7 %), fugitive dust (2.6±0.2 %) and industry (0.9±0.7 %). While the contribution of sea salt aerosol was persistent, as the dominant wind direction was south-westerly and westerly from the open ocean, the occurrence of mineral dust was episodic and coincided with high wind speeds from the south-south-east and the north-north-west, along the coastline. Concentrations of heavy metals measured at HBAO were higher than reported in the literature from measurements over the open ocean. V, Cd, Pb and Nd were attributed to fugitive dust emitted from bare surfaces or mining activities. As, Zn, Cu, Ni and Sr were attributed to the combustion of heavy oils in commercial ship traffic across the Cape of Good Hope sea route, power generation, smelting and other industrial activities in the greater region. Fluoride concentrations up to 25 µg m−3 were measured, as in heavily polluted areas in China. This is surprising and a worrisome result that has profound health implications and deserves further investigation. Although no clear signature for biomass burning could be determined, the PMF ammonium-neutralised component was described by a mixture of aerosols typically emitted by biomass burning, but also by other biogenic activities. Episodic contributions with moderate correlations between NO3-, nss-SO42- (higher than 2 µg m−3) and nss-K+ were observed, further indicative of the potential for an episodic source of biomass burning. Sea salt accounted for up to 57 % of the measured mass concentrations of SO42-, and the non-sea salt fraction was contributed mainly by the ammonium-neutralised component and small contributions from the mineral dust component. The marine biogenic contribution to the ammonium-neutralised component is attributed to efficient oxidation in the moist marine atmosphere of sulfur-containing gas phase emitted by marine phytoplankton in the fertile waters offshore in the Benguela Upwelling System. The data presented in this paper provide the first ever information on the temporal variability of aerosol concentrations in the Namibian marine boundary layer. This data also provide context for intensive observations in the area.

scholarly journals Characteristics of Aerosol during a Severe Haze-Fog Episode in the Yangtze River Delta: Particle Size Distribution, Chemical Composition, and Optical Properties

Atmosphere ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 56 ◽  
Author(s):  
Ankang Liu ◽  
Honglei Wang ◽  
Yi Cui ◽  
Lijuan Shen ◽  
Yan Yin ◽  
...  
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Chemical Composition ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Water Soluble ◽  
Air Masses ◽  
Soluble Ions ◽  
Wide Range ◽  
Water Soluble Ions

Particle size distribution, water soluble ions, and black carbon (BC) concentration in a long-term haze-fog episode were measured using a wide-range particle spectrometer (WPS), a monitor for aerosols and gases (MARGA), and an aethalometer (AE33) in Nanjing from 16 to 27 November, 2018. The observation included five processes of clean, mist, mix, haze, and fog. Combined with meteorological elements, the HYSPLIT model, and the IMPROVE model, we analyzed the particle size distribution, chemical composition, and optical properties of aerosols in different processes. The particle number size distribution (PNSD) in five processes differed: It was bimodal in mist and fog and unimodal in clean, mix, and haze. The particle surface area size distribution (PSSD) in different processes showed a bimodal distribution, and the second peak of the mix and fog processes shifted to a larger particle size at 480 nm. The dominant air masses in five processes differed and primarily originated in the northeast direction in the clean process and the southeast direction in the haze process. In the mist, mix, and fog processes local air masses dominated. NO3− was the primary component of water soluble ions, with the lowest proportion of 45.6% in the clean process and the highest proportion of 53.0% in the mix process. The ratio of NH4+ in the different processes was stable at approximately 23%. The ratio of SO42− in the clean process was 26.2%, and the ratio of other processes was approximately 20%. The average concentration of BC in the fog processes was 10,119 ng·m−3, which was 3.55, 1.80, 1.60, and 1.46 times that in the processes of clean, mist, mix, and haze, respectively. In the different processes, BC was primarily based on liquid fuel combustion. NO3−, SO42−, and BC were the main contributors to the atmospheric extinction coefficient and contributed more than 90% in different processes. NO3− contributed 398.43 Mm−1 in the mix process, and SO42− and BC contributed 167.90 Mm−1 and 101.19 Mm−1, respectively, during the fog process.

scholarly journals Chemical composition of boundary layer aerosol over the Atlantic Ocean and at an Antarctic site

2006 ◽  
Vol 6 (11) ◽  
pp. 3407-3421 ◽  
Author(s):  
A. Virkkula ◽  
K. Teinilä ◽  
R. Hillamo ◽  
V.-M. Kerminen ◽  
S. Saarikoski ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Atlantic Ocean ◽  
Biomass Burning ◽  
High Volume ◽  
Sea Salt ◽  
Saharan Dust ◽  
Submicron Particles ◽  
Research Station ◽  
Anthropogenic Influence ◽  
Anthropogenic Aerosol

Abstract. Aerosol chemical composition was measured over the Atlantic Ocean in November–December 1999 and at the Finnish Antarctic research station Aboa in January 2000. The concentrations of all anthropogenic aerosol compounds decreased clearly from north to south. An anthropogenic influence was still evident in the middle of the tropical South Atlantic, background values were reached south of Cape Town. Chemical mass apportionment was calculated for high volume filter samples (Dp<3 μm). North of the equator 70–80% of the aerosol consisted of non-sea-salt species. The contribution of sea salt was ~25% in the polluted latitudes, >80% in the Southern Ocean, and <10% at Aboa. The contribution of organic carbon was >10% in most samples, also at Aboa. The correlation of biomass-burning-related aerosol components with 210Pb was very high compared with that between nss calcium and 210Pb which suggests that 210Pb is a better tracer for biomass burning than for Saharan dust. The ratio of the two clear tracers for biomass burning, nss potassium and oxalate, was different in European and in African samples, suggesting that this ratio could be used as an indicator of biomass burning type. The concentrations of continent-related particles decreased exponentially with the distance from Africa. The shortest half-value distance, ~100 km, was for nss calcium. The half-value distance of particles that are mainly in the submicron particles was ~700±200 km. The MSA to nss sulfate ratio, R, increased faster than MSA concentration with decreasing anthropogenic influence, indicating that the R increase could largely be explained by the decrease of anthropogenic sulfate.

scholarly journals Chemical composition and aerosol size distribution of the middle mountain range in the Nepal Himalayas during the 2009 pre-monsoon season

2010 ◽  
Vol 10 (6) ◽  
pp. 15629-15670
Author(s):  
P. Shrestha ◽  
A. P. Barros ◽  
A. Khlystov
Keyword(s):  
Boundary Layer ◽  
Chemical Composition ◽  
Organic Carbon ◽  
Size Distribution ◽  
Elemental Carbon ◽  
Monsoon Season ◽  
Number Concentration ◽  
Water Soluble ◽  
Aerosol Size Distribution ◽  
Aerosol Number Concentration

Abstract. Aerosol particle number size distribution and chemical composition were measured at two low altitude sites, one urban and one relatively pristine valley, in Central Nepal during the 2009 pre-monsoon season (May–June). This is the first time that aerosol size distribution and chemical composition were measured simultaneously at lower elevation in the Middle Himalayan region in Nepal. The aerosol size distribution was measured using a Scanning Mobility Particle Sizer (SMPS, 14~340 nm), and the chemical composition of the filter samples collected during the field campaign was analyzed in the laboratory. Teflon membrane filters were used for ion chromatography (IC) and water-soluble organic carbon and nitrogen analysis. Quartz fiber filters were used for organic carbon and elemental carbon analysis. Multi-lognormal fits to the measured aerosol size distribution indicated a consistent larger mode around 100 nm which is usually the oldest, most processed background aerosol. The smaller mode was located around 20 nm, which is indicative of fresh but not necessarily local aerosol. The diurnal cycle of the aerosol number concentration showed the presence of two peaks (early morning and evening), during the transitional period of boundary layer growth and collapse. The increase in number concentration during the peak period was observed for the entire size distribution. Although the possible contribution of local emissions in size ranges similar to the larger mode cannot be completely ruled out, another plausible explanation is the mixing of aged elevated aerosol in the residual layer during the morning period as suggested by previous studies. Similarly, the evening time concentration peaks when the boundary layer becomes shallow concurrent with increase in local activity. A decrease in aerosol number concentration was observed during the nighttime with the development of cold (downslope) mountain winds that force the low level warmer air in the valley to rise. The mountain valley wind mechanisms induced by the topography along with the valley geometry appear to have a strong control in the diurnal cycle of the aerosol size distribution. During the sampling period, the chemical composition of PM2.5 was dominated by organic matter at both sites. Organic carbon (OC) comprised the major fraction (64~68%) of the aerosol concentration followed by ionic species (24~26% mainly SO42- and NH4+). Elemental Carbon (EC) compromised 7~10% of the total composition. A large fraction of OC was found to be water soluble (nearly 27% at both sites).

scholarly journals Chemical composition of boundary layer aerosol over the Atlantic Ocean and at an Antarctic site

2006 ◽  
Vol 6 (1) ◽  
pp. 455-491 ◽  
Author(s):  
A. Virkkula ◽  
K. Teinilä ◽  
R. Hillamo ◽  
V.-M. Kerminen ◽  
S. Saarikoski ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Atlantic Ocean ◽  
Biomass Burning ◽  
High Volume ◽  
Sea Salt ◽  
Saharan Dust ◽  
Submicron Particles ◽  
Research Station ◽  
Anthropogenic Influence ◽  
Anthropogenic Aerosol

Abstract. Aerosol chemical composition was measured over the Atlantic Ocean in November–December 1999 and at the Finnish Antarctic research station Aboa in January 2000. The concentrations of all anthropogenic aerosol compounds decreased clearly from north to south. An anthropogenic influence was still evident in the middle of the tropical South Atlantic, background values were reached south of Cape Town. Chemical mass balance was calculated for high volume filter samples (Dp<3 μm). North of the equator 70–80% of the aerosol consisted of non-sea-salt species. The contribution of sea salt was ~25% in the polluted latitudes, >80% in the Southern Ocean, and <10% at Aboa. The contribution of organic carbon was >10% in most samples, also at Aboa. The correlation of biomass-burning-related aerosol components with 210Pb was very high compared with that between nss calcium and 210Pb which suggests that 210Pb is a better tracer for biomass burning than for Saharan dust. The ratio of the two clear tracers for biomass burning, nss potassium and oxalate, was different in European and in African samples, suggesting that this ratio could be used as an indicator of biomass burning type. The concentrations of continent-related particles decreased exponentially with the distance from Africa. The shortest half-value distance, ~100 km, was for nss calcium. The half-value distance of particles that are mainly in the submicron particles was ~700±200 km. The MSA to nss sulfate ratio, R, increased faster than MSA concentration with decreasing anthropogenic influence, indicating that the R increase could largely be explained by the decrease of anthropogenic sulfate.

scholarly journals Earth System Model Aerosol-Cloud Diagnostics Package (ESMAC Diags) Version 1: Assessing E3SM Aerosol Predictions Using Aircraft, Ship, and Surface Measurements

2021 ◽  
Author(s):  
Shuaiqi Tang ◽  
Jerome D. Fast ◽  
Kai Zhang ◽  
Joseph C. Hardin ◽  
Adam C. Varble ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Size Distribution ◽  
Number Concentration ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Aerosol Cloud ◽  
Surface Measurements ◽  
Aerosol Number Concentration ◽  
Aerosol Properties

Abstract. An Earth System Model (ESM) aerosol-cloud diagnostics package is developed to facilitate the routine evaluation of aerosols, clouds and aerosol-cloud interactions simulated by the Department of Energy’s (DOE) Energy Exascale Earth System Model (E3SM). The first version focuses on comparing simulated aerosol properties with aircraft, ship, and surface measurements, most of them are measured in-situ. The diagnostics currently covers six field campaigns in four geographical regions: Eastern North Atlantic (ENA), Central U.S. (CUS), Northeastern Pacific (NEP) and Southern Ocean (SO). These regions produce frequent liquid or mixed-phase clouds with extensive measurements available from the Atmospheric Radiation Measurement (ARM) program and other agencies. Various types of diagnostics and metrics are performed for aerosol number, size distribution, chemical composition, CCN concentration and various meteorological quantities to assess how well E3SM represents observed aerosol properties across spatial scales. Overall, E3SM qualitatively reproduces the observed aerosol number concentration, size distribution and chemical composition reasonably well, but underestimates Aitken mode and overestimates accumulation mode aerosols over the CUS region, and underestimates aerosol number concentration over the SO region. The current version of E3SM struggles to reproduce new particle formation events frequently observed over both the CUS and ENA regions, indicating missing processes in current parameterizations. The diagnostics package is coded and organized in a way that can be easily extended to other field campaign datasets and adapted to higher-resolution model simulations. Future releases will include comprehensive cloud and aerosol-cloud interaction diagnostics.

scholarly journals Chemical composition and droplet size distribution of cloud at the summit of Mount Tai, China

2017 ◽  
Author(s):  
Jiarong Li ◽  
Xinfeng Wang ◽  
Jianmin Chen ◽  
Chao Zhu ◽  
Weijun Li ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Size Distribution ◽  
Droplet Size ◽  
Atmospheric Aerosols ◽  
Ph Value ◽  
Inorganic Ions ◽  
Droplet Size Distribution ◽  
Dilution Effect ◽  
Water Soluble ◽  
Cloud Droplets

Abstract. Chemical composition of 39 cloud samples and droplet size distribution in 24 cloud events were investigated at the summit of Mt. Tai from July to October 2014. Inorganic ions, organic acids, metals, HCHO, H2O2, sulfur(IV), organic carbon, element carbon as well as pH and electrical conductivity were analyzed. The acidity of the cloud water significantly decreased from a reported value of pH 3.86 in 2007–2008 (Guo et al., 2012) to pH 5.87 in the present study. The concentrations of nitrate and ammonium were both increased since 2007–2008, but the overcompensation of ammonium led to the increase of the mean pH value. The microphysical properties showed that cloud droplets were smaller than 26.0 μm and the most were in the range of 6.0–9.0 μm. The maximum droplet number concentration (Nd) was associated with droplet sizes of 7.0 μm. Cloud droplets exhibited a strong interaction with atmospheric aerosols. High PM2.5 level resulted in higher concentrations of water soluble ions and smaller sizes with more numbers of cloud droplets, and further gave rise to relatively high acidity. High degrees of relative humidity facilitated the formation of large cloud droplets and led to high liquid water contents under low PM2.5 level. The cloud droplets to wet deposition acted as an important sink of soluble material in the atmosphere and the dilution effect of the water content should be considered when estimating concentrations of soluble components in the cloud phase.

Sign in / Sign up

Export Citation Format

Share Document