scholarly journals On the functional form of particle number size distributions: influence of particle source and meteorological variables

2018 ◽  
Vol 18 (7) ◽  
pp. 4831-4842 ◽  
Author(s):  
Katia Cugerone ◽  
Carlo De Michele ◽  
Antonio Ghezzi ◽  
Vorne Gianelle ◽  
Stefania Gilardoni
Keyword(s):  
Particle Number ◽  
Functional Form ◽  
Size Range ◽  
Winter Season ◽  
Size Distributions ◽  
Weather Variables ◽  
Different Shapes ◽  
Distribution Family ◽  
Combustion Processes ◽  
Johnson System

Abstract. Particle number size distributions (PNSDs) have been collected periodically in the urban area of Milan, Italy, during 2011 and 2012 in winter and summer months. Moreover, comparable PNSD measurements were carried out in the rural mountain site of Oga–San Colombano (2250 m a.s.l.), Italy, during February 2005 and August 2011. The aerosol data have been measured through the use of optical particle counters in the size range 0.3–25 µm, with a time resolution of 1 min. The comparison of the PNSDs collected in the two sites has been done in terms of total number concentration, showing higher numbers in Milan (often exceeding 103 cm−3 in winter season) compared to Oga–San Colombano (not greater than 2×102 cm−3), as expected. The skewness–kurtosis plane has been used in order to provide a synoptic view, and select the best distribution family describing the empirical PNSD pattern. The four-parameter Johnson system-bounded distribution (called Johnson SB or JSB) has been tested for this aim, due to its great flexibility and ability to assume different shapes. The PNSD pattern has been found to be generally invariant under site and season changes. Nevertheless, several PNSDs belonging to the Milan winter season (generally more than 30 %) clearly deviate from the standard empirical pattern. The seasonal increase in the concentration of primary aerosols due to combustion processes in winter and the influence of weather variables throughout the year, such as precipitation and wind speed, could be considered plausible explanations of PNSD dynamics.

scholarly journals On the functional form of particle number size distributions: influence of particle source and meteorological variables

2017 ◽  
Author(s):  
Katia Cugerone ◽  
Carlo De Michele ◽  
Antonio Ghezzi ◽  
Vorne Gianelle ◽  
Stefania Gilardoni
Keyword(s):  
Particle Number ◽  
Functional Form ◽  
Size Range ◽  
Winter Season ◽  
Size Distributions ◽  
Weather Variables ◽  
Mountain Site ◽  
Different Shapes ◽  
Distribution Family ◽  
Combustion Processes

Abstract. Particle number size distributions (PNSDs) have been collected periodically in Milan urban area, Italy, during 2011 and 2012 in winter and summer months. Moreover, comparable PNSD measurements were carried out in the rural mountain site of Oga-San Colombano (2250 m a.s.l.), Italy, during February 2005 and August 2011. The aerosol data have been measured through the use of Optical Particle Counters in the size range 0.3–25 µm, mainly belonging to the coarse mode (PMcoarse), with a time resolution of one minute. The comparison of the PNSDs collected in the two sites has been done in terms of total number concentration, showing higher numbers in Milan (often exceeding 103 cm−3 in winter season) compared to Oga-San Colombano (not greater than 2 ∙ 102 cm−3), as expected. The skewness-kurtosis plane has been used in order to provide a synoptic view, and select the best distribution family describing the empirical PNSD pattern. The four-parameter Johnson SB (JSB) distribution has been tested for this aim, due to its great flexibility and ability of assuming different shapes. The PNSD pattern has been found to be generally invariant under site and season changes. Nevertheless, several PNSDs belonging to Milan winter season (generally more than 30 %) clearly deviate from the standard empirical pattern. The seasonal increase of the concentration of primary aerosols due to combustion processes in winter and the influence of weather variables, such as precipitation and wind speed, throughout the year, could be considered plausible explanations of PNSD dynamics.

scholarly journals Urban aerosol number size distributions

2004 ◽  
Vol 4 (2) ◽  
pp. 391-411 ◽  
Author(s):  
T. Hussein ◽  
A. Puustinen ◽  
P. P. Aalto ◽  
J. M. Mäkelä ◽  
K. Hämeri ◽  
...  
Keyword(s):  
Particle Number ◽  
Size Range ◽  
Particle Diameter ◽  
Temporal Variations ◽  
Number Concentration ◽  
Building Construction ◽  
Urban Aerosol ◽  
Size Distributions ◽  
Arithmetic Means ◽  
Accumulation Mode

Abstract. Aerosol number size distributions have been measured since 5 May 1997 in Helsinki, Finland. The presented aerosol data represents size distributions within the particle diameter size range 8-400nm during the period from May 1997 to March 2003. The daily, monthly and annual patterns of the aerosol particle number concentrations were investigated. The temporal variation of the particle number concentration showed close correlations with traffic activities. The highest total number concentrations were observed during workdays; especially on Fridays, and the lowest concentrations occurred during weekends; especially Sundays. Seasonally, the highest total number concentrations were observed during winter and spring and lower concentrations were observed during June and July. More than 80% of the number size distributions had three modes: nucleation mode (Dp<30nm), Aitken mode (20-100nm) and accumulation mode (Dp>90nm). Less than 20% of the number size distributions had either two modes or consisted of more than three modes. Two different measurement sites were used; in the first (Siltavuori, 5.5.1997-5.3.2001), the arithmetic means of the particle number concentrations were 7000cm-3, 6500cm-3, and 1000cm-3 respectively for nucleation, Aitken, and accumulation modes. In the second site (Kumpula, 6.3.2001-28.2.2003) they were 5500cm-3, 4000cm-3, and 1000cm-3. The total number concentration in nucleation and Aitken modes were usually significantly higher during workdays than during weekends. The temporal variations in the accumulation mode were less pronounced. The lower concentrations at Kumpula were mainly due to building construction and also the slight overall decreasing trend during these years. During the site changing a period of simultaneous measurements over two weeks were performed showing nice correlation at both sites.

scholarly journals Contribution of residential wood combustion and other sources to hourly winter aerosol in Northern Sweden determined by positive matrix factorization

2008 ◽  
Vol 8 (13) ◽  
pp. 3639-3653 ◽  
Author(s):  
P. Krecl ◽  
E. Hedberg Larsson ◽  
J. Ström ◽  
C. Johansson
Keyword(s):  
Matrix Factorization ◽  
Particle Number ◽  
Winter Season ◽  
Positive Matrix Factorization ◽  
Small Towns ◽  
Size Distributions ◽  
Northern Sweden ◽  
Wood Combustion ◽  
Positive Matrix ◽  
Mass Concentrations

Abstract. The combined effect of residential wood combustion (RWC) emissions with stable atmospheric conditions, which frequently occurs in Northern Sweden during wintertime, can deteriorate the air quality even in small towns. To estimate the contribution of RWC to the total atmospheric aerosol loading, positive matrix factorization (PMF) was applied to hourly mean particle number size distributions measured in a residential area in Lycksele during winter 2005/2006. The sources were identified based on the particle number size distribution profiles of the PMF factors, the diurnal contributions patterns estimated by PMF for both weekends and weekdays, and correlation of the modeled particle number concentration per factor with measured aerosol mass concentrations (PM10, PM1, and light-absorbing carbon MLAC) Through these analyses, the factors were identified as local traffic (factor 1), local RWC (factor 2), and local RWC plus long-range transport (LRT) of aerosols (factor 3). In some occasions, the PMF model could not separate the contributions of local RWC from background concentrations since their particle number size distributions partially overlapped. As a consequence, we report the contribution of RWC as a range of values, being the minimum determined by factor 2 and the possible maximum as the contributions of both factors 2 and 3. A multiple linear regression (MLR) of observed PM10, PM1, total particle number, and MLAC concentrations is carried out to determine the source contribution to these aerosol variables. The results reveal RWC is an important source of atmospheric particles in the size range 25–606 nm (44–57%), PM10 (36–82%), PM1 (31–83%), and MLAC (40–76%) mass concentrations in the winter season. The contribution from RWC is especially large on weekends between 18:00 LT and midnight whereas local traffic emissions show similar contributions every day.

scholarly journals Contribution of residential wood combustion to hourly winter aerosol in Northern Sweden determined by positive matrix factorization

2008 ◽  
Vol 8 (2) ◽  
pp. 5725-5760 ◽  
Author(s):  
P. Krecl ◽  
E. Hedberg Larsson ◽  
J. Ström ◽  
C. Johansson
Keyword(s):  
Matrix Factorization ◽  
Particle Number ◽  
Winter Season ◽  
Positive Matrix Factorization ◽  
Small Towns ◽  
Size Distributions ◽  
Northern Sweden ◽  
Wood Combustion ◽  
Positive Matrix ◽  
Mass Concentrations

Abstract. The combined effect of residential wood combustion (RWC) emissions with stable atmospheric conditions, which is a frequent occurrence in Northern Sweden during wintertime, can deteriorate the air quality even in small towns. To estimate the contribution of RWC to the total atmospheric aerosol loading, the positive matrix factorization (PMF) method was applied to hourly mean particle number size distributions measured in a residential area in Lycksele during winter 2005/2006. The sources were identified based on the particle number size distribution profiles of the PMF factors, the diurnal contributions patterns estimated by PMF for both weekends and weekdays, and correlation of the modeled particle number concentration per factor with measured aerosol mass concentrations (PM10, PM1, and light-absorbing carbon MLAC). Through these analyses, the factors were identified as local traffic (factor 1), local RWC (factor 2), and local RWC plus long-range transport (LRT) of aerosols (factor 3). In some occasions, it was difficult to detach the contributions of local RWC from background concentrations since their particle number size distributions partially overlapped and the model was not able to separate these two sources. As a consequence, we report the contribution of RWC as a range of values, being the minimum determined by factor 2 and the possible maximum as the contributions of both factors 2 and 3. A multiple linear regression (MLR) of observed PM10, PM1, total particle number, and MLAC concentrations is carried out to determine the source contribution to these aerosol variables. The results reveal RWC is an important source of atmospheric particles in the size range 25–606 nm (44–57%), PM10 (36–82%), PM1 (31–83%), and MLAC (40–76%) mass concentrations in the winter season. The contribution from RWC is especially large on weekends between 18:00 LT and midnight whereas local traffic emissions show similar contributions every day.

scholarly journals Evaluation and modeling of the size fractionated aerosol number concentration measurements near a major road in Helsinki

2007 ◽  
Vol 7 (2) ◽  
pp. 4001-4034
Author(s):  
T. Hussein ◽  
J. Kukkonen ◽  
H. Korhonen ◽  
M. Pohjola ◽  
L. Pirjola ◽  
...  
Keyword(s):  
Process Model ◽  
Particle Number ◽  
Size Range ◽  
Pearson Correlation ◽  
Substantial Contribution ◽  
Background Concentration ◽  
Size Distributions ◽  
Major Road ◽  
Urban Background ◽  
Concentration Measurements

Abstract. This study presents an evaluation and modeling of the size fractionated aerosol number concentrations that were measured near a major road of Itäväylä in Helsinki, during 23 August – 19 September 2003 and 14 January – 11 February 2004. The measurement system contained also electronic traffic counts, on-site meteorological measurements, and urban background concentration measurements. We have evaluated the temporal variations and the dependencies on local meteorological conditions of the measured aerosol number concentrations and size distributions. The ultrafine particle (UFP) number concentrations at the roadside site were approximately an order of magnitude higher than those at the urban background site during daytime, due to vehicular emissions from the road. We also determined the statistical correlations of the sequential time series of the particle number size distributions at the roadside site, and the traffic densities. The computed Pearson correlation coefficients for the downwind cases were substantially high for UFP's (>0.6), and low for accumulation mode particles; the latter is due to the substantial contribution of long-range transported particles in that size range. We also utilized this dataset for evaluating the performance of a modeling system that consists of a roadside dispersion model CAR-FMI (Contaminants in the Air from a Road – Finnish Meteorological Institute), a meteorological pre-processing model MPP-FMI and an aerosol process model UHMA (University of Helsinki Model for Aerosol processes). Model simulations underpredicted the particle number concentrations at the measurement site, which was caused by uncertainties in the emission modeling, especially in the UFP size range.

scholarly journals Aerosol particle number size distributions and particulate light absorption at the ZOTTO tall tower (Siberia), 2006–2009

2011 ◽  
Vol 11 (16) ◽  
pp. 8703-8719 ◽  
Author(s):  
J. Heintzenberg ◽  
W. Birmili ◽  
R. Otto ◽  
M. O. Andreae ◽  
J.-C. Mayer ◽  
...  
Keyword(s):  
Aerosol Particle ◽  
Forest Fires ◽  
Particle Number ◽  
Size Range ◽  
Geometric Mean ◽  
Potential Temperature ◽  
Size Distributions ◽  
Air Masses ◽  
Secondary Maximum ◽  
Tall Tower

Abstract. This paper analyses aerosol particle number size distributions, particulate absorption at 570 nm wavelength and carbon monoxide (CO) measured between September 2006 and January 2010 at heights of 50 and 300 m at the Zotino Tall Tower Facility (ZOTTO) in Siberia (60.8° N; 89.35° E). Average number, surface and volume concentrations are broadly comparable to former studies covering shorter observation periods. Fits of multiple lognormal distributions yielded three maxima in probability distribution of geometric mean diameters in the Aitken and accumulation size range and a possible secondary maximum in the nucleation size range below 25 nm. The seasonal cycle of particulate absorption shows maximum concentrations in high winter (December) and minimum concentrations in mid-summer (July). The 90th percentile, however, indicates a secondary maximum in July/August that is likely related to forest fires. The strongly combustion derived CO shows a single winter maximum and a late summer minimum, albeit with a considerably smaller seasonal swing than the particle data due to its longer atmospheric lifetime. Total volume and even more so total number show a more complex seasonal variation with maxima in winter, spring, and summer. A cluster analysis of back trajectories and vertical profiles of the pseudo-potential temperature yielded ten clusters with three levels of particle number concentration: Low concentrations in Arctic air masses (400–500 cm−3), mid-level concentrations for zonally advected air masses from westerly directions between 55° and 65° N (600–800 cm−3), and high concentrations for air masses advected from the belt of industrial and population centers in Siberia and Kazakhstan (1200 cm−3). The observational data is representative for large parts of the troposphere over Siberia and might be particularly useful for the validation of global aerosol transport models.

scholarly journals Configuration of the Martian dust rings: shapes, densities, and size distributions from direct integrations of particle trajectories

2020 ◽  
Vol 500 (3) ◽  
pp. 2979-2985
Author(s):  
Xiaodong Liu ◽  
Jürgen Schmidt
Keyword(s):  
Size Range ◽  
Solar Radiation Pressure ◽  
Dust Particles ◽  
Size Distributions ◽  
Grain Sizes ◽  
Gravitational Perturbations ◽  
Ring Configuration ◽  
Upper Limits ◽  
Configuration Simulation ◽  
Fifth Order

ABSTRACT It is expected since the early 1970s that tenuous dust rings are formed by grains ejected from the Martian moons Phobos and Deimos by impacts of hypervelocity interplanetary projectiles. In this paper, we perform direct numerical integrations of a large number of dust particles originating from Phobos and Deimos. In the numerical simulations, the most relevant forces acting on the dust are included: Martian gravity with spherical harmonics up to fifth degree and fifth order, gravitational perturbations from the Sun, Phobos, and Deimos, solar radiation pressure, as well as the Poynting–Robertson drag. In order to obtain the ring configuration, simulation results of various grain sizes ranging from submicrometres to 100 μm are averaged over a specified initial mass distribution of ejecta. We find that for the Phobos ring grains smaller than about 2 μm are dominant; while the Deimos ring is dominated by dust in the size range of about 5–20 μm. The asymmetries, number densities, and geometric optical depths of the rings are quantified from simulations. The results are compared with the upper limits of the optical depth inferred from Hubble observations. We compare to previous work and discuss the uncertainties of the models.

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