scholarly journals Cloud droplet activation in a continental Central European urban environment

2021 ◽  
Author(s):  
Imre Salma ◽  
Wanda Thén ◽  
Máté Vörösmarty ◽  
András Zénó Gyöngyösi
Keyword(s):  
Chemical Composition ◽  
Particle Number ◽  
Aerosol Particles ◽  
Ambient Air ◽  
Geometric Standard Deviation ◽  
Time Variability ◽  
Urban Aerosol ◽  
Large Variability ◽  
Frequency Distributions ◽  
Droplet Activation

Abstract. Collocated measurements by condensation particle counter, differential mobility particle sizer and cloud condensational nuclei counter instruments were realised in parallel in central Budapest from 15 April 2019 to 14 April 2020 to gain insight into the droplet activation behaviour of urban aerosol particles. The median total particle number concentration was 10.1 × 103 cm−3. The median concentrations of cloud condensation nuclei (CCN) at water vapour supersaturations (Ss) of 0.1, 0.2, 0.3, 0.5 and 1.0 % were 0.59, 1.09, 1.39, 1.80 and 2.5 × 103 cm−3, respectively. They represented from 7 to 27 % of the total particles. The effective critical dry particle diameters (dc,eff) were derived utilising the CCN concentrations and particle number size distributions. Their medians were 207, 149, 126, 105 and 80 nm, respectively. They were all positioned within the accumulation mode of the typical particle number size distribution. Their frequency distributions revealed a single peak, which geometric standard deviation increased monotonically with S. The broadening indicated larger time variability in the activation properties of smaller particles. The frequency distributions also showed a fine structure. Its several compositional elements seemed to change in a tendentious manner with S. They were related to the size-dependent chemical composition and external mixtures of particles. The relationships between the critical S and dc,eff suggested that the urban aerosol particles in Budapest with a diameter larger than approximately 130 nm showed similar hygroscopicity than the continental aerosol in general, while the smaller particles appeared to be less hygroscopic than that. Seasonal cycling of the CCN concentrations and activation fractions implied modest alterations and for the larger Ss only. They likely reflected the changes in particle number concentrations, chemical composition and mixing state of particles. The seasonal dependencies for dc,eff were featureless, which indicated that the urban particles exhibited more or less similar droplet activation properties over the measurement year. This is different from non-urban locations. The hygroscopicity parameters (κ values) were computed without determining time-dependent chemical composition of particles. Their medians were 0.16, 0.10, 0.07, 0.04 and 0.02, respectively. The averages suggested that the larger particles exhibited considerably higher hygroscopicity than the smaller particles. The urban aerosol was characterised by substantially smaller kappa values than for regional or remote locations. All these could be virtually linked to specific source composition in cities. The relatively large variability in the hygroscopicity parameter sets for a given S emphasized that their individual values represented the CCN population in the ambient air, while the averages stood mainly for the particles with a size close to the effective critical dry particle diameters.

scholarly journals Cloud activation properties of aerosol particles in a continental Central European urban environment

2021 ◽  
Vol 21 (14) ◽  
pp. 11289-11302
Author(s):  
Imre Salma ◽  
Wanda Thén ◽  
Máté Vörösmarty ◽  
András Zénó Gyöngyösi
Keyword(s):  
Chemical Composition ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Number Concentration ◽  
Urban Aerosol ◽  
Condensation Nuclei ◽  
Frequency Distributions ◽  
Remote Locations ◽  
Cloud Activation

Abstract. Collocated measurements using a condensation particle counter, differential mobility particle sizer and cloud condensation nuclei counter were realised in parallel in central Budapest from 15 April 2019 to 14 April 2020 to gain insight into the cloud activation properties of urban aerosol particles. The median total particle number concentration was 10.1 × 103 cm−3. The median concentrations of cloud condensation nuclei (CCN) at water vapour supersaturation (S) values of 0.1 %, 0.2 %, 0.3 %, 0.5 % and 1.0 % were 0.59, 1.09, 1.39, 1.80 and 2.5 × 103 cm−3, respectively. The CCN concentrations represented 7–27 % of all particles. The CCN concentrations were considerably larger but the activation fractions were systematically substantially smaller than observed in regional or remote locations. The effective critical dry particle diameters (dc,eff) were derived utilising the CCN concentrations and particle number size distributions. Their median values at the five supersaturation values considered were 207, 149, 126, 105 and 80 nm, respectively; all of these diameters were positioned within the accumulation mode of the typical particle number size distribution. Their frequency distributions revealed a single peak for which the geometric standard deviation increased monotonically with S. This broadening indicated high time variability in the activating properties of smaller particles. The frequency distributions also showed fine structure, with several compositional elements that seemed to reveal a consistent or monotonical tendency with S. The relationships between the critical S and dc,eff suggest that urban aerosol particles in Budapest with diameters larger than approximately 130 nm showed similar hydroscopicity to corresponding continental aerosol particles, whereas smaller particles in Budapest were less hygroscopic than corresponding continental aerosol particles. Only modest seasonal cycling in CCN concentrations and activation fractions was seen, and only for large S values. This cycling likely reflects changes in the number concentration, chemical composition and mixing state of the particles. The seasonal dependencies of dc,eff were featureless, indicating that the droplet activation properties of the urban particles remained more or less the same throughout the year. This is again different from what is seen in non-urban locations. Hygroscopicity parameters (κ values) were computed without determining the time-dependent chemical composition of the particles. The median values for κ were 0.15, 0.10, 0.07, 0.04 and 0.02, respectively, at the five supersaturation values considered. The averages suggested that the larger particles were considerably more hygroscopic than the smaller particles. We found that the κ values for the urban aerosol were substantially smaller than those previously reported for aerosols in regional or remote locations. All of these characteristics can be linked to the specific source composition of particles in cities. The relatively large variability in the hygroscopicity parameters for a given S emphasises that the individual values represent the CCN population in ambient air while the average hygroscopicity parameter mainly corresponds to particles with sizes close to the effective critical dry particle diameter.

scholarly journals Calibration of LACIS as a CCN detector and its use in measuring activation and hygroscopic growth of atmospheric aerosol particles

2006 ◽  
Vol 6 (12) ◽  
pp. 4519-4527 ◽  
Author(s):  
H. Wex ◽  
A. Kiselev ◽  
M. Ziese ◽  
F. Stratmann
Keyword(s):  
Sodium Chloride ◽  
Wall Temperature ◽  
Atmospheric Aerosol ◽  
Volume Fraction ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Urban Aerosol ◽  
Hygroscopic Growth ◽  
Atmospheric Aerosol Particles ◽  
Droplet Activation

Abstract. A calibration for LACIS (Leipzig Aerosol Cloud Interaction Simulator) for its use as a CCN (cloud condensation nuclei) detector has been developed. For this purpose, sodium chloride and ammonium sulfate particles of known sizes were generated and their grown sizes were detected at the LACIS outlet. From these signals, the effective critical super-saturation was derived as a function of the LACIS wall temperature. With this, LACIS is calibrated for its use as a CCN detector. The applicability of LACIS for measurements of the droplet activation, and also of the hygroscopic growth of atmospheric aerosol particles was tested. The activation of the urban aerosol particles used in the measurements was found to occur at a critical super-saturation of 0.46% for particles with a dry diameter of 75 nm, and at 0.42% for 85 nm, respectively. Hygroscopic growth was measured for atmospheric aerosol particles with dry diameters of 150, 300 and 350 nm at relative humidities of 98 and 99%, and it was found that the larger dry particles contained a larger soluble volume fraction of about 0.85, compared to about 0.6 for the 150 nm particles.

scholarly journals Spatio-temporal variability and principal components of the particle number size distribution in an urban atmosphere

2009 ◽  
Vol 9 (9) ◽  
pp. 3163-3195 ◽  
Author(s):  
F. Costabile ◽  
W. Birmili ◽  
S. Klose ◽  
T. Tuch ◽  
B. Wehner ◽  
...  
Keyword(s):  
Size Distribution ◽  
Particle Number ◽  
Aerosol Particles ◽  
Urban Traffic ◽  
Urban Atmosphere ◽  
Urban Aerosol ◽  
Number Size Distribution ◽  
Spatio Temporal ◽  
20 Nm ◽  
Aitken Mode

Abstract. A correct description of fine (diameter <1 μm) and ultrafine (<0.1 μm) aerosol particles in urban areas is of interest for particle exposure assessment but also basic atmospheric research. We examined the spatio-temporal variability of atmospheric aerosol particles (size range 3–800 nm) using concurrent number size distribution measurements at a maximum of eight observation sites in and around Leipzig, a city in Central Europe. Two main experiments were conducted with different time span and number of observation sites (2 years at 3 sites; 1 month at 8 sites). A general observation was that the particle number size distribution varied in time and space in a complex fashion as a result of interaction between local and far-range sources, and the meteorological conditions. To identify statistically independent factors in the urban aerosol, different runs of principal component (PC) analysis were conducted encompassing aerosol, gas phase, and meteorological parameters from the multiple sites. Several of the resulting PCs, outstanding with respect to their temporal persistence and spatial coverage, could be associated with aerosol particle modes: a first accumulation mode ("droplet mode", 300–800 nm), considered to be the result of liquid phase processes and far-range transport; a second accumulation mode (centered around diameters 90–250 nm), considered to result from primary emissions as well as aging through condensation and coagulation; an Aitken mode (30–200 nm) linked to urban traffic emissions in addition to an urban and a rural Aitken mode; a nucleation mode (5–20 nm) linked to urban traffic emissions; nucleation modes (3–20 nm) linked to photochemically induced particle formation; an aged nucleation mode (10–50 nm). Additional PCs represented only local sources at a single site, or infrequent phenomena. In summary, the analysis of size distributions of high time and size resolution yielded a surprising wealth of statistical aerosol components occurring in the urban atmosphere over one single city. A paradigm on the behaviour of sub-μm urban aerosol particles is proposed, with recommendations how to efficiently monitor individual sub-fractions across an entire city.

scholarly journals Spatio-temporal variability and principal components of the particle number size distribution in an urban atmosphere

2008 ◽  
Vol 8 (5) ◽  
pp. 18155-18217 ◽  
Author(s):  
F. Costabile ◽  
W. Birmili ◽  
S. Klose ◽  
T. Tuch ◽  
B. Wehner ◽  
...  
Keyword(s):  
Particle Number ◽  
Aerosol Particles ◽  
Urban Traffic ◽  
Urban Atmosphere ◽  
Urban Aerosol ◽  
Size Distributions ◽  
Spatial Coverage ◽  
Temporal Persistence ◽  
Spatio Temporal ◽  
20 Nm

Abstract. Due to the presence of diffusive anthropogenic sources in urban areas, the spatio-temporal variability of fine (diameter <1 μm) and ultrafine (<0.1 μm) aerosol particles has been a challenging issue in particle exposure assessment as well as atmospheric research in general. We examined number size distributions of atmospheric aerosol particles (size range 3–800 nm) that were measured simultaneously at a maximum of eight observation sites in and around a city in Central Europe (Leipzig, Germany). Two main experiments were conducted with different time span and number of observation sites (2 years at 3 sites; 1 month at 8 sites). A general observation was that the particle number size distribution varied in time and space in a complex fashion as a result of interaction between local and far-range sources, and the meteorological conditions. To identify statistically independent factors in the urban aerosol, different runs of principal component analysis were conducted encompassing aerosol, gas phase, and meteorological parameters from the multiple sites. Several of the resulting principal components, outstanding with respect to their temporal persistence and spatial coverage, could be associated with aerosol particle modes: a first accumulation mode ("droplet mode", 300–800 nm), considered to be the result of liquid phase processes and far-range transport; a second accumulation mode (centered around diameters 90–250 nm), considered to result from primary emissions as well as aging through condensation and coagulation; an Aitken mode (30–200 nm) linked to urban traffic emissions in addition to an urban and a rural Aitken mode; a nucleation mode (5–20 nm) linked to urban traffic emissions; nucleation modes (3–20 nm) linked to photochemically induced particle formation; an aged nucleation mode (10–50 nm). A number of additional components were identified to represent only local sources at a single site each, or infrequent phenomena. In summary, the analysis of size distributions of high time and size resolution yielded a surprising wealth of statistical aerosol components occurring in the urban atmosphere over one single city. Meanwhile, satisfactory physical explanations could be found for the components with the greatest temporal persistence and spatial coverage. Therefore a paradigm on the behaviour of sub-μm urban aerosol particles is proposed, with recommendations how to efficiently monitor individual sub-fractions across an entire city.

scholarly journals Photochemical aging of aerosol particles in different air masses arriving at Baengnyeong Island, Korea

2018 ◽  
Vol 18 (9) ◽  
pp. 6661-6677 ◽  
Author(s):  
Eunha Kang ◽  
Meehye Lee ◽  
William H. Brune ◽  
Taehyoung Lee ◽  
Taehyun Park ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Mass Concentration ◽  
Aerosol Particles ◽  
Ambient Air ◽  
The Yellow Sea ◽  
Chemical Compositions ◽  
Scanning Mobility Particle Sizer ◽  
Air Masses ◽  
Aerosol Mass ◽  
Photochemical Aging

Abstract. Atmospheric aerosol particles are a serious health risk, especially in regions like East Asia. We investigated the photochemical aging of ambient aerosols using a potential aerosol mass (PAM) reactor at Baengnyeong Island in the Yellow Sea during 4–12 August 2011. The size distributions and chemical compositions of aerosol particles were measured alternately every 6 min from the ambient air or through the highly oxidizing environment of a potential aerosol mass (PAM) reactor. Particle size and chemical composition were measured by using the combination of a scanning mobility particle sizer (SMPS) and a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). Inside the PAM reactor, O3 and OH levels were equivalent to 4.6 days of integrated OH exposure at typical atmospheric conditions. Two types of air masses were distinguished on the basis of the chemical composition and the degree of aging: air transported from China, which was more aged with a higher sulfate concentration and O  :  C ratio, and the air transported across the Korean Peninsula, which was less aged with more organics than sulfate and a lower O  :  C ratio. For both episodes, the particulate sulfate mass concentration increased in the 200–400 nm size range when sampled through the PAM reactor. A decrease in organics was responsible for the loss of mass concentration in 100–200 nm particles when sampled through the PAM reactor for the organics-dominated episode. This loss was especially evident for the m∕z 43 component, which represents less oxidized organics. The m∕z 44 component, which represents further oxidized organics, increased with a shift toward larger sizes for both episodes. It is not possible to quantify the maximum possible organic mass concentration for either episode because only one OH exposure of 4.6 days was used, but it is clear that SO2 was a primary precursor of secondary aerosol in northeast Asia, especially during long-range transport from China. In addition, inorganic nitrate evaporated in the PAM reactor as sulfate was added to the particles. These results suggest that the chemical composition of aerosols and their degree of photochemical aging, particularly for organics, are also crucial in determining aerosol mass concentrations.

scholarly journals Calibration of LACIS as a CCN detector and its use in measuring activation and hygroscopic growth of atmospheric aerosol particles

2006 ◽  
Vol 6 (4) ◽  
pp. 5877-5904
Author(s):  
H. Wex ◽  
A. Kiselev ◽  
M. Ziese ◽  
F. Stratmann
Keyword(s):  
Sodium Chloride ◽  
Wall Temperature ◽  
Atmospheric Aerosol ◽  
Volume Fraction ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Urban Aerosol ◽  
Hygroscopic Growth ◽  
Atmospheric Aerosol Particles ◽  
Droplet Activation

Abstract. A calibration for LACIS (Leipzig Aerosol Cloud Interaction Simulator) for its use as a CCN (cloud condensation nuclei) detector has been developed. For this purpose, sodium chloride and ammonium sulfate particles of known sizes were generated and their grown sizes were detected at the LACIS outlet. From these signals, the effective critical super-saturation was derived as a function of the LACIS wall temperature. With this, LACIS is calibrated for its use as a CCN detector. The applicability of LACIS for measurements of the droplet activation, and also of the hygroscopic growth of atmospheric aerosol particles was tested. The activation of the urban aerosol particles used in the measurements was found to occur at a critical super-saturation of 0.46% for particles with a dry diameter of 75 nm, and at 0.42% for 85 nm, respectively. Hygroscopic growth was measured for atmospheric aerosol particles with dry diameters of 150, 300 and 350 nm at relative humidities of 98 and 99%, and it was found that the larger dry particles contained a larger soluble volume fraction of about 0.85, compared to about 0.6 for the 150 nm particles.

scholarly journals Temporal Variations in Chemical Composition, In Vitro Digestibility, and Metabolizable Energy of Plant Species Browsed by Goats in Southern Mediterranean Forest Rangeland

Animals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1441
Author(s):  
Youssef Chebli ◽  
Samira El Otmani ◽  
Mouad Chentouf ◽  
Jean-Luc Hornick ◽  
Jean-François Cabaraux
Keyword(s):  
Chemical Composition ◽  
Plant Species ◽  
Nutritive Value ◽  
Condensed Tannin ◽  
Metabolizable Energy ◽  
Mediterranean Forest ◽  
In Vitro Digestibility ◽  
Large Variability ◽  
Southern Mediterranean

Forest rangelands contribute largely to goat diets in the Mediterranean area. Information about browsed plant quality is essential for adequate feeding management. The purpose of this study was to evaluate the temporal changes in chemical composition and in vitro digestibility of the main plant species selected by goats in the Southern Mediterranean forest rangeland during two consecutive years; these were very contrasted (dry and wet). The browsed species were composed of herbaceous, eleven shrubs, and four tree species. Overall, large variability in chemical composition, in vitro organic matter digestibility (IVOMD), and metabolizable energy (ME) was observed among species, grazing season (spring, summer, and autumn), and years within each species. Crude protein (CP) content varied from 60 to 240 g/kg dry matter (DM). The fiber fractions, except for Quercus suber, increased significantly by advancing maturity. Due to the water stress, the lignin level presented a higher value during the spring of the dry year. Condensed tannin (CT) content varied from 2 to 184 g/kg DM. CP, IVOMD, and ME showed a negative correlation with lignin and CT. Based on the results presented herein, it is concluded that the nutritive value of the browsed plant species was highest in the spring and lowest during the summer and autumn of both studied years. With a good grazing management strategy, the selected plant species by goats could guarantee high-quality feeding resources throughout the year.

Sign in / Sign up

Export Citation Format

Share Document