scholarly journals Aerosol properties, source identification, and cloud processing in orographic clouds measured by single particle mass spectrometry on a Central European mountain site during HCCT-2010

2015 ◽  
Vol 15 (17) ◽  
pp. 24419-24472 ◽  
Author(s):  
A. Roth ◽  
J. Schneider ◽  
T. Klimach ◽  
S. Mertes ◽  
D. van Pinxteren ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Single Particle ◽  
Mass Spectra ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Algorithm Analysis ◽  
Sorting Algorithm ◽  
Condensation Nuclei ◽  
Cloud Processing ◽  
Orographic Clouds

Abstract. Cloud residues and out-of-cloud aerosol particles with diameters between 150 and 900 nm have been analysed by on-line single particle aerosol mass spectrometry during the six-week study HCCT-2010 in September/October 2010. The measurement location was the mountain Schmücke (937 m a.s.l.) in Central Germany. More than 170 000 bipolar mass spectra from out-of-cloud aerosol particles and more than 14 000 bipolar mass spectra from cloud residual particles were obtained and were classified using a fuzzy c-means clustering algorithm. Analysis of the uncertainty of the sorting algorithm was conducted on a subset of the data by comparing the clustering output with particle-by-particle inspection and classification by the operator. This analysis yielded a false classification probability between 13 and 48 %. Additionally, particle types were identified by specific marker ions. The results from the ambient aerosol analysis show that 63 % of the analysed particles belong to clusters indicating a diurnal variation, suggesting that local or regional sources dominate the aerosol, especially for particles containing soot and biomass burning particles. In the cloud residues the relative percentage of large soot-containing particles and particles containing amines was found to be increased compared to the out-of-cloud aerosol, while in general organic particles were less abundant in the cloud residues. In the case of amines this can be explained by the high solubility of the amines, while the large soot-containing particles were found to be internally mixed with inorganics, which explains their activation as cloud condensation nuclei. Furthermore, the results show that during cloud processing, both sulphate and nitrate are added to the residual particles, thereby changing the mixing state and increasing the fraction of particles with nitrate and/or sulphate. This is expected to lead to higher hygroscopicity after cloud evaporation, and therefore to an increase of the particles' ability to act as cloud condensation nuclei after their cloud passage.

scholarly journals Aerosol properties, source identification, and cloud processing in orographic clouds measured by single particle mass spectrometry on a central European mountain site during HCCT-2010

2016 ◽  
Vol 16 (2) ◽  
pp. 505-524 ◽  
Author(s):  
A. Roth ◽  
J. Schneider ◽  
T. Klimach ◽  
S. Mertes ◽  
D. van Pinxteren ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Single Particle ◽  
Mass Spectra ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Algorithm Analysis ◽  
Sorting Algorithm ◽  
Condensation Nuclei ◽  
Cloud Processing ◽  
Orographic Clouds

Abstract. Cloud residues and out-of-cloud aerosol particles with diameters between 150 and 900 nm were analysed by online single particle aerosol mass spectrometry during the 6-week study Hill Cap Cloud Thuringia (HCCT)-2010 in September–October 2010. The measurement location was the mountain Schmücke (937 m a.s.l.) in central Germany. More than 160 000 bipolar mass spectra from out-of-cloud aerosol particles and more than 13 000 bipolar mass spectra from cloud residual particles were obtained and were classified using a fuzzy c-means clustering algorithm. Analysis of the uncertainty of the sorting algorithm was conducted on a subset of the data by comparing the clustering output with particle-by-particle inspection and classification by the operator. This analysis yielded a false classification probability between 13 and 48 %. Additionally, particle types were identified by specific marker ions. The results from the ambient aerosol analysis show that 63 % of the analysed particles belong to clusters having a diurnal variation, suggesting that local or regional sources dominate the aerosol, especially for particles containing soot and biomass burning particles. In the cloud residues, the relative percentage of large soot-containing particles and particles containing amines was found to be increased compared to the out-of-cloud aerosol, while, in general, organic particles were less abundant in the cloud residues. In the case of amines, this can be explained by the high solubility of the amines, while the large soot-containing particles were found to be internally mixed with inorganics, which explains their activation as cloud condensation nuclei. Furthermore, the results show that during cloud processing, both sulfate and nitrate are added to the residual particles, thereby changing the mixing state and increasing the fraction of particles with nitrate and/or sulfate. This is expected to lead to higher hygroscopicity after cloud evaporation, and therefore to an increase of the particles' ability to act as cloud condensation nuclei after their cloud passage.

scholarly journals On-line determination of the chemical composition of single activated cloud condensation nuclei – a first investigation of single urban CCN and CCN obtained from sea water samples

2020 ◽  
Author(s):  
Carmen Dameto de España ◽  
Anna Wonaschuetz ◽  
Gerhard Steiner ◽  
Harald Schuh ◽  
Constantinos Sioutas ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Single Particle ◽  
Indirect Effect ◽  
Water Samples ◽  
Sea Water ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Condensation Nuclei ◽  
San Sebastian

Abstract. Cloud condensation nuclei (CCN) play an important role in cloud microphysics and are crucial for the second indirect effect of aerosols on global climate. One of the uncertainties in calculations of the indirect effect is due to insufficient data on CCN activation. The formation and growth processes of aerosol particles which subsequently become CCN determine their chemical composition. Due to the numerous organic and inorganic components present in atmospheric aerosol particles, a determination of the chemical composition of individual CCN is still challenging. To expand our understanding of activation of real-world CCN we introduce a novel method to characterize the chemical composition of single activated CCN in their droplet state. This method consists of a coupling of two essential instruments, a CCN-VACES (Cloud Condensation Nuclei-Versatile Aerosol Concentration Enrichment System) which is a modification of the original VACES to select and enrich CCN concentrations, and a Laser Ablation Aerosol Particle Time of Flight mass spectrometer (LAAPTOF), a single particle mass spectrometer. In the CCN-VACES, an aerosol flow is exposed to a specific water vapour supersaturation (in this study: 0.035 %, 0.054 %, 0.1 % and 0.6 %, respectively) and the CCN in the flow grow to droplets if their critical supersaturation is exceeded. These grown droplets are subsequently enriched in concentration by means of a virtual impactor at the end of the growth region by a factor of ca. 16 and pass directly into a LAAPTOF to measure the chemical composition of individual activated droplets. Contrary to widely held beliefs, the LAAPTOF is able to analyse refractory and non-refractory components even in aqueous droplets and can therefore be used to determine the chemical composition of actually activated CCN in their droplet state. Single particle spectra (for both positive and negative ions) were obtained from activated CCN in the ambient aerosol as well as activated CCN originating from aerosolized sea water samples collected at two different regions (Palma de Mallorca and San Sebastián, Spain). Ambient CCN were found to contain sometimes highly complex mixtures of different carbonaceous and non-carbonaceous components. Sea water derived CCN show the expected content of sea salt constituents, but the presence of organics is also observed. Activated CCN from the San Sebastián water samples have stronger sulphate signals than the Mallorca water sample. The LAAPTOF was found to provide insights into the composition of individual activated CCN.

scholarly journals Improved identification of primary biological aerosol particles using single particle mass spectrometry

2016 ◽  
Author(s):  
Maria A. Zawadowicz ◽  
Karl D. Froyd ◽  
Daniel M. Murphy ◽  
Daniel J. Cziczo
Keyword(s):  
Mass Spectrometry ◽  
Single Particle ◽  
Mass Spectra ◽  
Aerosol Particles ◽  
Particle Mass ◽  
Cloud Formation ◽  
Single Particle Mass Spectrometry ◽  
Ambient Data ◽  
By Products ◽  
Biological Aerosol Particles

Abstract. Measurements of primary biological aerosol particles, especially at altitudes relevant to cloud formation, are scarce. Single particle mass spectrometry (SPMS) has been used to probe aerosol chemical composition from ground and aircraft for over 20 years. Here we develop a method for identifying bioaerosols using SPMS. We show that identification of bioaerosol using SPMS is complicated because phosphorus-bearing mineral dust and phosphorus-rich combustion by-products such as fly ash produce mass spectra with peaks similar to those typically used as markers for bioaerosol. We have developed a methodology to differentiate and identify bioaerosol using machine learning statistical techniques applied to mass spectra of known particle types. This improved method provides far fewer false positives compared to approaches reported in the literature. The new method was then applied to ambient data collected at Storm Peak Laboratory to show that 0.04–0.3 % of particles in the 200–3000 nm aerodynamic diameter range were identified as bioaerosol.

scholarly journals Improved identification of primary biological aerosol particles using single-particle mass spectrometry

2017 ◽  
Vol 17 (11) ◽  
pp. 7193-7212 ◽  
Author(s):  
Maria A. Zawadowicz ◽  
Karl D. Froyd ◽  
Daniel M. Murphy ◽  
Daniel J. Cziczo
Keyword(s):  
Mass Spectrometry ◽  
Single Particle ◽  
Mass Spectra ◽  
Mineral Dust ◽  
Aerosol Particles ◽  
Central Valley ◽  
Particle Mass ◽  
Cloud Formation ◽  
Single Particle Mass Spectrometry ◽  
Biological Aerosol Particles

Abstract. Measurements of primary biological aerosol particles (PBAP), especially at altitudes relevant to cloud formation, are scarce. Single-particle mass spectrometry (SPMS) has been used to probe aerosol chemical composition from ground and aircraft for over 20 years. Here we develop a method for identifying bioaerosols (PBAP and particles containing fragments of PBAP as part of an internal mixture) using SPMS. We show that identification of bioaerosol using SPMS is complicated because phosphorus-bearing mineral dust and phosphorus-rich combustion by-products such as fly ash produce mass spectra with peaks similar to those typically used as markers for bioaerosol. We have developed a methodology to differentiate and identify bioaerosol using machine learning statistical techniques applied to mass spectra of known particle types. This improved method provides far fewer false positives compared to approaches reported in the literature. The new method was then applied to two sets of ambient data collected at Storm Peak Laboratory and a forested site in Central Valley, California to show that 0.04–2 % of particles in the 200–3000 nm aerodynamic diameter range were identified as bioaerosol. In addition, 36–56 % of particles identified as biological also contained spectral features consistent with mineral dust, suggesting internal dust–biological mixtures.

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 Intercomparison of modal and sectional aerosol microphysics representations within the same 3-D global chemical transport model

2012 ◽  
Vol 12 (1) ◽  
pp. 623-689 ◽  
Author(s):  
G. W. Mann ◽  
K. S. Carslaw ◽  
D. A. Ridley ◽  
D. V. Spracklen ◽  
K. J. Pringle ◽  
...  
Keyword(s):  
Size Distribution ◽  
Transport Model ◽  
Cloud Condensation Nuclei ◽  
Particle Growth ◽  
Free Troposphere ◽  
Chemical Transport Model ◽  
Condensation Nuclei ◽  
Chemistry Transport Model ◽  
Surface Mass ◽  
Cloud Processing

Abstract. A global modal aerosol microphysics module (GLOMAP-mode) is evaluated and improved by comparing against a sectional version (GLOMAP-bin) and observations in the same 3-D global offline chemistry transport model. With both schemes, the model captures the main features of the global particle size distribution, with sub-micron aerosol approximately unimodal in continental regions and bi-modal in marine regions. Initial bin-mode comparisons showed that various size distribution parameter settings (mode widths and inter-modal separation sizes) resulted in clear biases compared to the sectional scheme. By adjusting these parameters in the modal scheme, much better agreement is achieved against the bin scheme and observations. Surface mass of sulphate, sea-salt, black carbon (BC) and organic carbon (OC) are, on the annual mean, within 25 % in the two schemes in nearly all regions. On the annual mean, surface level concentrations of condensation nuclei (CN), cloud condensation nuclei (CCN), surface area density and condensation sink also compare within 25 % in most regions. However, marine CCN concentrations between 30° N and 30° S are systematically higher in the modal scheme, by 25–60 %, which we attribute to differences in size-resolved particle growth or cloud-processing. Larger differences also exist in regions or seasons dominated by biomass burning and in free-troposphere and high-latitude regions. Indeed, in the free-troposphere, GLOMAP-mode BC is a factor 2–4 higher than GLOMAP-bin, likely due to differences in size-resolved scavenging. Nevertheless, in most parts of the atmosphere, we conclude that bin-mode differences are much less than model-observation differences, although some processes are missing in these runs which may pose a bigger challenge to modal schemes (e.g. boundary layer nucleation, ultra-fine sea-spray). The findings here underline the need for a spectrum of complexity in global models, with size-resolved aerosol properties predicted by modal schemes needing to be continually benchmarked and improved against freely evolving sectional schemes and observations.

scholarly journals Effects of Cloud Condensation Nuclei and Ice Nucleating Particles on Precipitation Processes and Supercooled Liquid in Mixed-phase Orographic Clouds

2016 ◽  
Author(s):  
Jiwen Fan ◽  
L. Ruby Leung ◽  
Daniel Rosenfeld ◽  
Paul J. DeMott
Keyword(s):  
Water Content ◽  
Sierra Nevada ◽  
Cloud Condensation Nuclei ◽  
Supercooled Water ◽  
Mixed Phase ◽  
Condensation Nuclei ◽  
Local Circulation ◽  
Orographic Clouds ◽  
Snow Precipitation ◽  
Mixed Phase Clouds

Abstract. How orographic mixed-phase clouds respond to the change of cloud condensation nuclei (CCN) and ice nucleating particles (INPs) are highly uncertain. The main snow production mechanism in warm and cold mixed-phase orographic clouds (referred to as WMOC and CMOC, respectively, distinguished here as those having cloud tops warmer and colder than −20 °C) could be very different. We quantify the CCN and INP impacts on supercooled water content, cloud phases and precipitation for a WMOC and a CMOC case with a set of sensitivity tests. It is found that deposition plays a more important role than riming for forming snow in the CMOC, while the role of riming is dominant in the WMOC case. As expected, adding CCN suppresses precipitation especially in WMOC and low INP. However, this reverses strongly for CCN > 1000 cm−3. We find a new mechanism through which CCN can invigorate mixed-phase clouds over the Sierra Nevada Mountains and drastically intensify snow precipitation when CCN concentrations are high (1000 cm−3 or higher). In this situation, more widespread shallow clouds with greater amount of cloud water form in the valley and foothills, which changes the local circulation through more latent heat release that transports more moisture to the windward slope, leading to much more invigorated mixed-phase clouds over the mountains that produce higher amounts of snow precipitation. Increasing INPs leads to decreased riming and mixed-phase fraction in the CMOC but has the opposite effects in the WMOC, as a result of liquid-limited and ice-limited conditions, respectively. However, it increases precipitation in both cases due to an increase of deposition for the CMOC but enhanced riming and deposition in the WMOC. Increasing INPs dramatically reduces supercooled water content and increases the cloud glaciation temperature, while increasing CCN has the opposite effects with much smaller significance.

scholarly journals Resonance-Enhanced Detection of Metals in Aerosols using Single Particle Mass Spectrometry

2020 ◽  
Author(s):  
Johannes Passig ◽  
Julian Schade ◽  
Ellen Iva Rosewig ◽  
Robert Irsig ◽  
Thomas Kröger-Badge ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Excimer Laser ◽  
Single Particle ◽  
Aerosol Particles ◽  
Ambient Air ◽  
Particle Mass ◽  
Anthropogenic Aerosols ◽  
Single Particle Mass Spectrometry ◽  
Krf Excimer Laser ◽  
The Impact

Abstract. We describe resonance effects in laser desorption/ionization (LDI) of particles that substantially increase the sensitivity and selectivity to metals in single particle mass spectrometry (SPMS). Within the proposed scenario, resonant light absorption by ablated metal atoms increases their ionization rate within a single laser pulse. By choosing the appropriate laser wavelength, the key micronutrients Fe, Zn and Mn can be detected on individual aerosol particles with considerably improved efficiency. These ionization enhancements for metals apply to natural dust and anthropogenic aerosols, both important sources of bioavailable metals to marine environments. Transferring the results into applications, we show that the spectrum of our KrF-excimer laser is in resonance with a major absorption line of iron atoms. To estimate the impact of resonant LDI on the metal detection efficiency in SPMS applications, we performed a field experiment on ambient air with two alternately firing excimer lasers of different wavelengths. Herein, resonant LDI with the KrF-excimer laser (248.3 nm) revealed Fe signatures for many more aerosol particles compared to the more common ArF-excimer laser line of 193.3 nm. Moreover, resonant ionization of iron appeared to be less dependent on the particle matrix than conventional non-resonant LDI, allowing a more universal and secure detection of Fe. Our findings show a way to improve the detection and source attribution capabilities of SPMS for particle-bound metals, a health-relevant aerosol component and an important source of micronutrients to the surface oceans affecting marine primary productivity.

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