scholarly journals Determination of Fitted Size Distribution for Atmospheric Aerosols

2017 ◽  
Vol 14 (2) ◽  
Author(s):  
Kaitlin DuPaul ◽  
Adam Whitten
Keyword(s):  
Particle Swarm Optimization ◽  
Size Distribution ◽  
Atmospheric Aerosols ◽  
Particle Swarm ◽  
Bimodal Distribution ◽  
Aerosol Size Distribution ◽  
Size Distributions ◽  
Swarm Optimization ◽  
Large Variability ◽  
Lognormal Distributions

A synthetic set of aerosol optical depths (AODs) generated from a standard set of aerosol size distributions was analyzed by a parameter based particle swarm optimization (PBPSO) routine in order to test the reproducibility of the results. Junge and lognormal size distributions were consistently reproduced. Gamma and bimodal distributions showed large variability in solutions. values were used to determine the best subset of possible solutions allowing quantification of parameters with uncertainties when using PBPSO. AODs measured by a sun photometer on a clear day (20160413) and a foggy day (20160508) were then processed by the PBPSO program for both bimodal and lognormal distributions. Results showed that in general the foggy day has smaller values indicating that the PBPSO algorithm is better able to match AODs when there is a larger aerosol load in the atmosphere. The bimodal distribution from the clear day best describes the aerosol size distribution since the values are lower. The lognormal distribution best describes the aerosol size distribution on the foggy day (20160508). KEYWORDS: Atmospheric Aerosols; Size Distributions; Junge; Bimodal; Gamma; Lognormal; Particle Swarm Optimization; Inverse Problem; Aerosol Optical Depth

Determination of atmospheric aerosol particle size distribution and visibility using a mobile laboratory

1982 ◽  
Vol 60 (8) ◽  
pp. 1101-1107
Author(s):  
C. V. Mathai ◽  
A. W. Harrison
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Atmospheric Aerosols ◽  
Suspended Particle ◽  
Aerosol Size Distribution ◽  
Size Distributions ◽  
Mobile Laboratory ◽  
Mean Values ◽  
The City

As part of an ongoing general research program on the effects of atmospheric aerosols on visibility and its dependence on aerosol size distributions in Calgary, this paper presents the results of a comparative study of particle size distribution and visibility in residential (NW) and industrial (SE) sections of the city using a mobile laboratory. The study was conducted in the period October–December, 1979. An active scattering aerosol spectrometer measured the size distributions and the corresponding visibilities were deduced from scattering coefficients measured with an integrating nephelometer.The results of this transit study show significantly higher suspended particle concentrations and reduced visibilities in the SE than in the NW. The mean values of the visibilities are 44 and 97 km for the SE and the NW respectively. The exponent of R (particle radius) in the power law aerosol size distribution has a mean value of −3.36 ± 0.24 in the SE compared with the corresponding value of −3.89 ± 0.39 for the NW. These results arc in good agreement with the observations of Alberta Environment; however, they are in contradiction with a recent report published by the City of Calgary.

scholarly journals Inversion of particle size distribution by spectral extinction technique using the attractive and repulsive particle swarm optimization algorithm

2015 ◽  
Vol 19 (6) ◽  
pp. 2151-2160 ◽  
Author(s):  
Hong Qi ◽  
Zhen-Zong He ◽  
Shuai Gong ◽  
Li-Ming Ruan
Keyword(s):  
Particle Size ◽  
Particle Swarm Optimization ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Particle Swarm ◽  
Incident Laser ◽  
Swarm Optimization ◽  
N Distribution ◽  
Repulsive Particle Swarm Optimization ◽  
Inverse Results

The particle size distribution (PSD) plays an important role in environmental pollution detection and human health protection, such as fog, haze and soot. In this study, the Attractive and Repulsive Particle Swarm Optimization (ARPSO) algorithm and the basic PSO were applied to retrieve the PSD. The spectral extinction technique coupled with the Anomalous Diffraction Approximation (ADA) and the Lambert-Beer Law were employed to investigate the retrieval of the PSD. Three commonly used monomodal PSDs, i.e. the Rosin-Rammer (R-R) distribution, the normal (N-N) distribution, the logarithmic normal (L-N) distribution were studied in the dependent model. Then, an optimal wavelengths selection algorithm was proposed. To study the accuracy and robustness of the inverse results, some characteristic parameters were employed. The research revealed that the ARPSO showed more accurate and faster convergence rate than the basic PSO, even with random measurement error. Moreover, the investigation also demonstrated that the inverse results of four incident laser wavelengths showed more accurate and robust than those of two wavelengths. The research also found that if increasing the interval of the selected incident laser wavelengths, inverse results would show more accurate, even in the presence of random error.

scholarly journals Investigation of Atmospheric Aerosol Size Distributions from Ground-Based Solar Spectrometer Measurements Synthesized with Satellite Data

2019 ◽  
Vol 16 (1) ◽  
pp. 23-32
Author(s):  
Dane Kuhr ◽  
Adam Whitten
Keyword(s):  
Particle Swarm Optimization ◽  
Aerosol Particle ◽  
Satellite Imagery ◽  
Forest Fires ◽  
Atmospheric Aerosol ◽  
Particle Swarm ◽  
Size Distributions ◽  
Number Density ◽  
Swarm Optimization ◽  
Aitken Mode

Data collected by a ground-based solar spectrometer at Collegeville, MN, was used to generate Aerosol Optical Depths (AODs) throughout the 2017 calendar year. The AOD data was then visualized at 13 selected wavelengths throughout the year and analyzed in comparison to satellite imagery, upper air charts and backwards trajectories of air masses moving towards Central Minnesota in order to determine key dates of interest that correspond to times before (20170615), during (20170729), and at the conclusion of (20170914) forest fires that burned in British Columbia (BC) during the summer of 2017. The data from these specific days were analyzed further by inputting the maximum and minimum AODs for each day into a Parameter Based Particle Swarm Optimization (PBPSO) algorithm in order to generate bimodal lognormal particle size distributions. The bimodal distributions were chosen because they carry more information about the aerosol loads across the entire spectrum of particle radii. The resulting distributions show an increase in number density and decrease in median radius in the Aitken mode during the BC forest fires and a relatively constant (within uncertainty) number density of accumulation mode particles at daily maximum AODs. Comparing the resulting bimodal lognormal distribution for daily minimum AODs (where evaporation and other diurnal effects are at a minimum) shows an increased number density of Aitken mode particles by two orders of magnitude from pre- to post-forest fires. This measured increase in the number density of smaller radii particles due to forest fires illustrates the PBPSO’s capability of distinguishing variations in atmospheric aerosol particle number size distributions in the Aitken mode based on data collected by the Kipp-Zonen PGS-100 solar spectrometer. KEYWORDS: Atmospheric Aerosol; Particle Swarm Optimization; Aerosol Optical Depth; Solar Spectrometer; Size Distributions; Forest Fire; Satellite Imagery; Upper Air Charts; Backward Trajectory

scholarly journals Lake spray aerosol generation: A method for producing representative particles from freshwater wave breaking

2016 ◽  
Author(s):  
Nathaniel W. May ◽  
Jessica L. Axson ◽  
Alexa Watson ◽  
Kerri A. Pratt ◽  
Andrew P. Ault
Keyword(s):  
Size Distribution ◽  
Atmospheric Aerosols ◽  
Wave Breaking ◽  
Lake Michigan ◽  
Cloud Condensation Nuclei ◽  
Aerosol Size Distribution ◽  
Size Distributions ◽  
Salt Solutions ◽  
Synthetic Seawater ◽  
Aerosol Generation

Abstract. Wave breaking action in bodies of freshwater produces atmospheric aerosols via a similar mechanism to sea spray aerosol (SSA) from seawater. The term lake spray aerosol (LSA) is proposed to describe particles formed by this mechanism, which have been observed over the Laurentian Great Lakes. Though LSA has been identified from size distribution measurements during a single measurement campaign, no measurements of LSA composition or relationship to bubble bursting dynamics have been conducted. A LSA generator utilizing a plunging jet, similar to many SSA generators, was constructed for the generation of aerosol from freshwater samples and model salt solutions. To evaluate this new generator, bubble and aerosol number size distributions were measured for salt solutions representative of freshwater (CaCO3) and seawater (NaCl) at concentrations ranging from that of freshwater to seawater (0.05–35 g L−1), synthetic seawater (inorganic), synthetic freshwater (inorganic), and a freshwater sample from Lake Michigan. Following validation of the bubble and aerosol size distributions using synthetic seawater, a range of salt concentrations was investigated. Decreasing salt concentrations from seawater to freshwater led to greater bubble coalescence and formation of larger bubbles, which generated larger particles and lower aerosol number concentrations. The systematic studies of the model salts, synthetic freshwater, and Lake Michigan sample indicate that LSA is characterized by a larger bubble size distribution, compared to seawater, with a peak near 300 μm. This resulted in a bimodal aerosol size distribution with a primary mode (180 ± 20 nm) larger than that of SSA, and a secondary mode (46 ± 6 nm) smaller than that of SSA. This new method for studying LSA under isolated conditions is needed as models, at present, utilize SSA parametrizations for freshwater systems, which are not accurate for predicting climate properties of the different size distributions observed for LSA. Given the abundance of freshwater globally, this potentially important source of aerosol needs to be thoroughly characterized, as the sizes produced are relevant to light scattering, cloud condensation nuclei (CCN), and ice nuclei (IN) concentrations over the bodies of freshwater.

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