Optical scattering patterns from single urban aerosol particles at Adelphi, Maryland, USA: A classification relating to particle morphologies

Aptowicz, Kevin B.; Pinnick, Ronald G.; Hill, Steven C.; Pan, Yong‐Le; Chang, Richard K.

doi:10.1029/2005jd006774

Cited by 58 publications

(45 citation statements)

References 66 publications

(96 reference statements)

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“…Alternatively, the aerodynamic particle size is determined from the time it takes a particle to travel a given distance (as measured by light scattering at two positions). Some instruments measure elastic scattering from many angles and try to deduce something about particle shape (49). However, elastic scattering instruments are relatively uninformative regarding chemical composition.…”

Section: Some Instrumentation Used To Measure Bioaerosolsmentioning

confidence: 99%

Fluorescence of Bacteria, Pollens, and Naturally Occurring Airborne Particles: Excitation/Emission Spectra

Hill¹,

Mayo²,

Chang³

2009

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Approved for public release; distribution unlimited. FOR OFFICIAL USE ONLYii REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

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Section: Some Instrumentation Used To Measure Bioaerosolsmentioning

confidence: 99%

Fluorescence of Bacteria, Pollens, and Naturally Occurring Airborne Particles: Excitation/Emission Spectra

Hill¹,

Mayo²,

Chang³

2009

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“…The forward-scattering detector is additionally split into four quadrants that separately record intensity, quantifying the asymmetry factor (AF) of the scattering pattern. The morphology of a particle affects this pattern (Aptowicz et al, 2006) and AF in turn provides rudimentary information about the relative shape of each particle in an aerosol population. In this work we will refer only briefly to this aspect of the data to highlight general relative changes in particle morphology.…”

Section: Instrument Descriptionmentioning

confidence: 99%

Observations of fluorescent and biological aerosol at a high-altitude site in central France

et al. 2013

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Total bacteria, fungal spore and yeast counts were compared with ultraviolet-light-induced fluorescence (UV-LIF) measurements of ambient aerosol at the summit of the Puy de Dôme (PdD) mountain in central France (1465 m a.s.l), which represents a background elevated site. Bacteria, fungal spores and yeast were enumerated by epifluorescence microscopy (EFM) and found to number 2.2 to 23 L⁻¹ and 0.8 to 2 L⁻¹, respectively. Bacteria counts on two successive nights were an order of magnitude larger than in the intervening day.

A wide issue bioaerosol spectrometer, version 3 (WIBS-3) was used to perform UV-LIF measurements on ambient aerosol sized 0.8 to 20 μm. Mean total number concentration was 270 L⁻¹ (σ = 66 L⁻¹), found predominantly in a size mode at 2 μm for most of the campaign. Total concentration (fluorescent + non-fluorescent aerosol) peaked at 500 L⁻¹ with a size mode at 1 μm because of a change in air mass origin lasting around 48 h. The WIBS-3 features two excitation and fluorescence detection wavelengths corresponding to different biological molecules, although non-biological interferents also contribute. The mean fluorescent particle concentration after short-wave (280 nm; associated with tryptophan) excitation was 12 L⁻¹ (σ = 6 L⁻¹), and did not vary much throughout the campaign. In contrast, the mean concentration of particles fluorescent after long-wave (370 nm; associated with NADH) excitation was 95 L⁻¹ (σ = 25 L⁻¹), and a nightly rise and subsequent fall of up to 100 L⁻¹ formed a strong diurnal cycle in the latter. The two fluorescent populations exhibited size modes at 3 μm and 2 to 3 μm, respectively. A hierarchical agglomerative cluster analysis algorithm was applied to the data and used to extract different particle factors. A cluster concentration time series representative of bacteria was identified. This was found to exhibit a diurnal cycle with a maximum peak appearing during the day.

Analysis of organic mass spectra recorded using an aerosol mass spectrometer (AMS; Aerodyne Inc.) suggests that aerosol reaching the site at night was more aged than that during the day, indicative of sampling the residual layer at night. Supplementary meteorological data and previous work also show that PdD lies in the residual layer/free troposphere at night, and this is thought to cause the observed diurnal cycles in organic-type and fluorescent aerosol particles.

Based on the observed disparity between bacteria and fluorescent particle concentrations, fluorescent non-PBA is likely to be important in the WIBS-3 data and the surprisingly high fluorescent concentration in the residual layer/free troposphere raises questions about a ubiquitous background in continental air during the summer

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“…More details are provided by the captions. From the early versions of the 1990's [3] , the design and implementation of TAOS instrumentation has advanced to the point of being field-deployable and fit for outdoor or indoor air sampling [13] . A typical collected pattern is shown by FIGURE 3.…”

Section: Methodsmentioning

confidence: 99%

Automated classification of single airborne particles from two-dimension, angle-resolved optical scattering (TAOS) patterns

2011

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Two-dimension, angle-resolved optical scattering (TAOS) is an experimental technique by which patterns of LASER light intensity scattered by single (micrometer or sub-micrometer sized) airborne particles are collected. In the past 10 years TAOS instrumentation has evolved from laboratory prototypes to field-deployable equipment; patterns are collected by the thousands during indoor or outdoor sampling in short times. Although comparison between experimental and computed scattering patterns has been carried out extensively, there is no satisfactory way to relate a given pattern to the particle it comes from. This paper reports about the ongoing development and implementation of a method which is aimed at classifying patterns, rather than identifying original particles. A machine learning algorithm includes the extraction of morphological features and their multivariate statistical analysis. A classifier is trained and validated in a supervised mode, by relying on patterns from known materials. Then the tuned classifier is applied to the recognition of patterns of unknown origin.

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Optical scattering patterns from single urban aerosol particles at Adelphi, Maryland, USA: A classification relating to particle morphologies

Cited by 58 publications

References 66 publications

Fluorescence of Bacteria, Pollens, and Naturally Occurring Airborne Particles: Excitation/Emission Spectra

Fluorescence of Bacteria, Pollens, and Naturally Occurring Airborne Particles: Excitation/Emission Spectra

Observations of fluorescent and biological aerosol at a high-altitude site in central France

Automated classification of single airborne particles from two-dimension, angle-resolved optical scattering (TAOS) patterns

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