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

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  µ m, 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.

[1]  C. De Michele,et al.  Investigating raindrop size distributions in the (L‐)skewness–(L‐)kurtosis plane , 2017 .

[2]  C. Michele,et al.  Capabilities of the Johnson SB distribution in estimating rain variables , 2016 .

[3]  J. M. Fernández-Guisuraga,et al.  Nitrogen oxides and ozone in Portugal: trends and ozone estimation in an urban and a rural site , 2016, Environmental Science and Pollution Research.

[4]  C. De Michele,et al.  Johnson SB as general functional form for raindrop size distribution , 2015 .

[5]  I. Riipinen,et al.  Particulate matter, air quality and climate: Lessons learned and future needs , 2015 .

[6]  M. Rao,et al.  Using the NO2/NOx Ratio to Understand the Spatial Heterogeneity of Secondary Pollutant Formation Capacity in Urban Atmospheres , 2014 .

[7]  D. Massabò,et al.  Spatial and seasonal variability of carbonaceous aerosol across Italy , 2014 .

[8]  Richard T. Burnett,et al.  How is cardiovascular disease mortality risk affected by duration and intensity of fine particulate matter exposure? An integration of the epidemiologic evidence , 2011 .

[9]  Raghu Pasupathy,et al.  Moment-Ratio Diagrams for Univariate Distributions , 2010 .

[10]  W. Landman.  Climate change 2007: the physical science basis , 2010 .

[11]  D. Dockery,et al.  Health Effects of Fine Particulate Air Pollution: Lines that Connect , 2006, Journal of the Air & Waste Management Association.

[12]  B. Rudolf,et al.  World Map of the Köppen-Geiger climate classification updated , 2006 .

[13]  Roberta Vecchi,et al.  The role of atmospheric dispersion in the seasonal variation of PM1 and PM2.5 concentration and composition in the urban area of Milan (Italy) , 2004 .

[14]  Peter Wåhlin,et al.  A European aerosol phenomenology—1: physical characteristics of particulate matter at kerbside, urban, rural and background sites in Europe , 2004 .

[15]  John R. Stedman,et al.  Studies of the coarse particle (2.5–10 μm) component in UK urban atmospheres , 2001 .

[16]  M. L. Laucks,et al.  Aerosol Technology Properties, Behavior, and Measurement of Airborne Particles , 2000 .

[17]  J. Seinfeld,et al.  Atmospheric Chemistry and Physics: From Air Pollution to Climate Change , 1998 .

[18]  S. Schwartz.  The whitehouse effect—Shortwave radiative forcing of climate by anthropogenic aerosols: an overview , 1996 .

[19]  N. L. Johnson,et al.  Continuous Univariate Distributions. , 1995 .

[20]  W. K. Brown,et al.  Derivation of the Weibull distribution based on physical principles and its connection to the Rosin–Rammler and lognormal distributions , 1995 .

[21]  N. Standish,et al.  A study of particle size distributions , 1990 .

[22]  J. Klett,et al.  Microphysics of Clouds and Precipitation , 1978, Nature.

[23]  O. Barndorff-Nielsen.  Exponentially decreasing distributions for the logarithm of particle size , 1977, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[24]  K. T. Whitby,et al.  Concentration and Size Distribution Measurements of Atmospheric Aerosols and a Test of the Theory of Self-Preserving Size Distributions , 1967 .

[25]  D. Deirmendjian.  Scattering and Polarization Properties of Water Clouds and Hazes in the Visible and Infrared , 1964 .

[26]  C. Craig.  A New Exposition and Chart for the Pearson System of Frequency Curves , 1936 .

[27]  A. Ghezzi,et al.  Aerosol removal due to precipitation and wind forcings in Milan urban area , 2018 .

[28]  H. Walton,et al.  Health Risks of Air Pollution in Europe HRAPIE Project , 2013 .

[29]  G. Gennaro,et al.  Sources of high PM2.5 concentrations in Milan, Northern Italy: molecular marker data and CMB modelling. , 2012, The Science of the total environment.

[30]  G. Leeuw,et al.  Birmingham Number size distributions and seasonality of submicron particles in Europe 2008–2009 , 2011 .

[31]  Yangang Liu,et al.  On the description of aerosol particle size distribution , 1994 .

[32]  G. Isaac,et al.  Tropospheric aerosol size distributions from 1982 to 1988 over eastern North America , 1991 .

[33]  K. T. Whitby.  THE PHYSICAL CHARACTERISTICS OF SULFUR AEROSOLS , 1978 .

[34]  R. Jaenicke,et al.  The mathematical expression of the size distribution of atmospheric aerosols , 1976 .

[35]  Samuel S. Butcher,et al.  An Introduction to Air Chemistry , 1972 .

[36]  D. Deirmendjian.  Electromagnetic scattering on spherical polydispersions , 1969 .

[37]  C. Junge,et al.  Air chemistry and radioactivity , 1963 .

[38]  P. Rosin.  The Laws Governing the Fineness of Powdered Coal , 1933 .

[39]  Karl Pearson,et al.  Mathematical Contributions to the Theory of Evolution. XIX. Second Supplement to a Memoir on Skew Variation , 1901 .