On applicability of model aerosol distributions for urban region of Bratislava city |
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| Institution: | 1. Department of Interplanetary Matter, Astronomical Institute, Slovak Academy of Sciences, Dúbravská cesta 9, 842 28 Bratislava, Slovak Republic;2. Geophysical Institute, Slovak Academy of Sciences, Dúbravská cesta 9, 842 28 Bratislava, Slovak Republic;3. Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic;1. Headache Science Center, IRCCS C. Mondino Foundation, Pavia, Italy;2. Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy;3. Center for Pain and the Brain, Boston Children''s Hospital and Massachusetts General Hospital (MGH), Harvard Medical School, Boston, MA, USA;1. China Center for Special Economic Zone Research, College of Economics, Shenzhen University, Guangdong, 518060, China;2. School of Business and Creative Industries, University of the Sunshine Coast, 90 Sippy Downs Drive, Sippy Downs, QLD, 4556, Australia;1. Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, UK;2. Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Public Health, London School of Hygiene and Tropical Medicine, London, UK |
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| Abstract: | Long-term measurements of spectral atmospheric transparency are analysed to describe the aerosol size distribution as well as the aerosol optical thickness in the urban region of Bratislava city, capital of Slovak Republic. Aerosol characteristics are related to the most frequent air masses, especially to the continental polar (cP—with a 54% occurrence) and maritime polar (mP—with 34% occurrence), to the wind direction and speed, as well as to the relative humidity. Including both random and systematic errors of the observations into the calculation procedures, the aerosol optical thickness is obtained with approximately 4% error at all wavelengths. Averaged values of the aerosol optical thickness τa(λ) at reference wavelength λ=520 nm vary over a wide range, from 0.1 to 0.7. Besides, the aerosol optical thickness of the continental polar air mass is obviously higher than corresponding values in the maritime polar air mass. It is shown that the transformation inside the air mass reflects the changes of the optical characteristics of aerosols, especially during decay of air mass. The function τa(λ) seems to be monomodal in the majority of cases, with the mode position about λ≈400 nm for cP, and λ≈500 nm for mP. A value of power parameter δ of the function τa(λ)≈λ?δ is about 0.8–1.6 for maritime polar and about 0.3–1.2 for continental polar. Two simple model functions (Junge and gamma) are examined to find a best fit of real distribution retrieved from the aerosol optical thickness data using the inverse techniques based on Mellin transform. The gamma function much better than Junge's function supply the real aerosol component of all studied air masses (mainly for cP and mP). The average modal radius of gamma distribution practically does not exceed the value of 0.06 μm. Real distributions retrieved using a Mellin transform give an averaged morning value of particle modal radius rm about 0.084 μm, and averaged daily value rm about 0.054 μm. |
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