10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
High Temporal Resolution Analysis of Fine Particles Concentrations in 5D Virtual Space
LIBOR HEJKRLÍK, Helena Plachá, Dáša Richterová, Czech Hydrometeorological Institute
Abstract Number: 320 Working Group: Remote/Regional Atmospheric Aerosol
Abstract Number concentrations N of fine particles had been measured by SMPS in 7 channels (10–20 nm, 20–30 nm, 30–50 nm, 50–70 nm, 70–100 nm, 100–200 nm, 200–800 nm) with time resolution of one hour since June 2012 to December 2015 at a background urban site in Northern Bohemia. At the same measuring station of the National Air Pollution Network operated by the Czech Hydrometeorological Institute hourly means of three pollutants had been measured (mass concentrations of SO2, NO2 and PM1 – black carbon). At two nearby climatological stations one-hour values of three meteorological elements were available (air temperature Th, relative air humidity Hh and global radiation Rh). The whole period of observations covered 1309 days, periodically involving all of the seasons of the year with no respect to weekdays or rush hours. Night hours (Rh=0) were excluded even though they amounted to more than one half of available data. Th varied between 11,2 °C and 36,1 °C, for Hh it was between 21% and 100% and Rh reached its extremes between 0,2 and 940,5 W/m2. The maximum of mean concentration of SO2 slightly exceeded the level 20 μg/m3/hour, the highest value for NO2 was registered at 100 μg/m3/hour and PM1 was mostly less than 14 μg/m3/hour. Resulting number of analyzed rows of 5 variables (in two versions, one for SO2 and another for NO2) was approximately 14 000. The nearly-continuous combinations of meteorological data were transformed into THREE-DIMENSIONAL matrix where Th, Hh and Rh were assigned only few discrete values (48, 13 and 13 respectively). In the resulting 8112 cells of the 3D matrix mean concentrations of the modes of fine particles were calculated. To clarify the whole picture only the cells containing at least 15 values of N were taken into account. The results were displayed in the form of XYZ bubble graph, diameters of the spheres being the FOURTH dimension. GrapherTM 11 (Golden Software, LLC) enables colouring of the bubbles regarding specific key, in this case one of four classes of mean hourly concentration of SO2 or NO2 in corresponding cells. The colour of the spheres may be regarded as the FIFTH dimension. The nucleation modes of nanoparticles (10–50 nm) demonstrate strong proliferation (N~104/cm3/hour) under extreme both temperature and solar radiation while air moisture remains moderate. The overall picture changes for fine particles with diameter up to 800 nm. Their concentrations are one order less, the maximum values show considerable affinity to periods of low visibility and high humidity. They are possibly primary particles of anthropogenic origin; this is also supported by practically identical graphs for numeric concentrations of particles with diameter 200–800 nm and for mass concentrations of PM1, obtained by MAAP instrument, it is by different physical method. Highest quantities of nanoparticles correlate with elevated concentrations of sulphur dioxide, whereas concentrations of NO2 are low. The picture gradually fades out towards 50 nm limit probably due to advancing nucleation of sulphuric acid formed from the atmospheric oxidation of SO2. Primary particles 50–800 nm reach their maximal values in correspondence with anthropogenically induced high concentrations of sulphur dioxide, probably of industrial origin as well as with elevated values of nitrogen dioxide that is a strong indicator of vehicle emissions.