National Repository of Grey Literature 86 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Black carbon measuruments comparison
Vítová, Jana ; Zíková, Naděžda (advisor) ; Vondráková Pokorná, Petra (referee)
This thesis focuses on comparing three devices designed for measuring equivalent black carbon (referred to as eBC - equivalent black carbon), specifically the MAAP instrument (Multi-Angle Absorption Photometer) model 5012, the Aethalometer model AE33, and a semi-continuous analyzer of organic and elemental carbon. The instruments collected eBC concentrations at the Institute of Chemical Process Fundamentals of the Czech Academy of Sciences (Ústav chemických procesů AV ČR, v.v.i.) in the northwest of Prague from October 4, 2021, to September 30, 2022. Initially, total eBC concentrations were compared between all mentioned instruments using the non-parametric Wilcoxon test. Subsequently, daily, weekly, and annual variations in BC were determined. Finally, values of the Ångström absorption coefficient, mass absorption cross section (MAC), and harmonization factor C, which had not been determined for the mentioned measurement area, were calculated. For all instruments, a mutual agreement was found, confirmed by correlation coefficients: AE33 and MAAP with r=0.88, AE33 and OC/EC with r=0.83, and MAAP and OC/EC with r=0.76. The coefficients of determination between individual instruments were also obtained: AE33 and OC/EC with Rš=0.68, OC/EC and MAAP with Rš=0.57, and AE33 and MAAP with Rš=0.77. The...
PHYSICOCHEMICAL CHARACTERISTICS AND EVOLUTION OF AEROSOL FROM OPEN COMBUSTION OF BIOMASS DURING THE TRADITIONAL “BURNING OF THE WITCHES”
Mbengue, Saliou ; Vodička, Petr ; Komínková, Kateřina ; Schwarz, Jaroslav ; Zíková, Naděžda ; Vítková, Gabriela ; Windell, Laurence Christian ; Suchánková, Lenka ; Lhotka, Radek ; Julaha, Kajal ; Prokeš, Roman ; Šmejkalová Holubová, A. ; Ondráček, Jakub ; Ždímal, Vladimír ; Holoubek, Ivan
Open biomass burning (OBB) is a major source releasing large quantities of gaseous and particulate pollutants into the atmosphere, with global, regional and local impacts on air quality, public health and climate (Andreae, 2019, Chen et al., 2017). OBB aerosols mainly consist of carbonaceous matter, and a considerable amount of inorganic salts, which present distinctly different optical properties (Chen et al., 2017, Reid et al., 2005). In this study, we investigate the influence of OBB during the traditional Burning of the Witches (BoW), referred to in Czech as “Pálení čarodějnic”, on the physico-chemical properties of atmospheric aerosols collected at the National Atmospheric Observatory Košetice (NAOK). The BoW is a centuries-old pagan tradition very popular in the Czech Republic. Today, it is celebrated during the night from April 30 to May 1 by lighting bonfires made of woodpiles with fake witches.
ON OUR RECENT WORK IN STUDYING NEW PARTICLE FORMATION (NPF)
Kovářík, Jiří ; Špalová, Anna ; Roztočil, Petr ; Zíková, Naděžda ; Schwarz, Jaroslav ; Ždímal, Vladimír
New particle formation (NPF) is increasingly gaining attention since it emerged roughly twenty years ago as a field of interest within the aerosol science. It studies the transition process between gas phase molecules, forming clusters and eventually becoming aerosol particles. Thus, this field is a multidisciplinary one, ranging from meteorology, atmospheric chemistry and physics, all the way through physical chemistry towards chemistry and physics of aerosols. \nRecent development of instrumentation techniques allows measuring of sub-5 nm particles and molecule clusters, neutral and also charged ones. Therefore, modern analytical methods based on these measurements are often used for NPF studies.
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WATER-SOLUBLE COMPOUNDS PM2.5 AT THREE RURAL BACKGROUND SITES IN CENTRAL EUROPE DURING COLD AND WARM PERIODS
Schwarz, Jaroslav ; Vodička, Petr ; Lhotka, Radek ; Pokorná, Petra ; Zíková, Naděžda ; Ondráček, Jakub ; Aurora, S. ; Poulain, L. ; Herrmann, H. ; Ždímal, Vladimír
Ion chromatography (IC) was used to characterize water soluble compounds in PM2.5 during winter and summer campaigns at three rural sites in Central Europe in 12-hour (day/night) time resolution. Concentrations of biomass combustion aerosolsdoubled from Melpitz to Košetice in winter, sea salt exhibited opposite behaviour. Summer exhibited higher sulphates and methane sulphonic acid in Melpitz. Day to night ratios showed higher day concentrations for phosphates and compounds connected to fungal spores and bacteria, while higher night concentrations were connected to wood combustion. Ventilation index was used as an approximate measure to distinguish local and long range transported aerosols. Biomass combustion products were identified as the \nmajority of local aerosols, while sea salt as long range transported one.
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SUBMICRON AEROSOL AT TWO URBAN STATIONS IN PRAGUE
Pokorná, Petra ; Zíková, Naděžda ; Vodička, Petr ; Lhotka, Radek ; Ondráček, Jakub ; Schwarz, Jaroslav ; Ždímal, Vladimír ; Hopke, P.
The aim of this work was to determine the submicron aerosol dynamics, chemical compositions, and origins at two sites in Prague based on the particle number size distribution (PNSD) and chemical composition of 2/12/24h atmospheric aerosol samples (PM1) collected in parallel for half-year/within two seasons at two urban sites (suburban – Suchdol and traffic – Vršovice). Chemical analysis of PM1 for carbon (elemental, equivalent black – eBC and organic) by thermo-optical method and for water-soluble inorganic ions by IC was performed. For most months, both number and mass median \nconcentrations based on the SMPS data differed. Higher eBC concentrations were measured in Vršovice however eBC concentrations showed good correlation (r=0.80, yintercept=0) at the two stations. Higher average PM1 at the traffic site in summer and at the suburban site in winter, and seasonal differences in ionic PM1 composition reflected the seasonality of the local sources. Nevertheless, there were no statistically significant differences in PM1 concentration and ionic composition between the sites.
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HIGHLY-TIME RESOLVED ELEMENTAL SOURCE APPORTIONMENT OF PM2.5 AT AN URBAN TRAFFIC SITE IN PRAGUE
Windell, Laurence Christian ; Pokorná, Petra ; Ondráček, Jakub ; Schwarz, Jaroslav ; Lhotka, Radek ; Vodička, Petr ; Zíková, Naděžda ; Hopke, P.K. ; Ždímal, Vladimír
This work aims to quantify metal emissions from traffic at an urban traffic site in Prague, Czech Republic, identify key tracers of emissions, and investigate exhaust and non-exhaust emissions observable in fine particulate matter (PM2.5). This project signifies the first high-time resolution elemental analysis of Prague aerosols.
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DRONE-BASED VERTICAL MEASUREMENTS OF BLACK CARBON AEROSOLS AT A RURAL BACKGROUND AND AN URBAN SITE
Julaha, Kajal ; Zíková, Naděžda ; Ždímal, Vladimír
Black Carbon (BC) aerosols are primary particles emitted into the atmosphere as a by-product of incomplete combustion processes. BC absorbs solar radiation and altersthe radiation budget of the Earth(Bond et al., 2013). The radiative properties of BC heavily depend on its vertical profiles(Haywood and Ramaswamy, 1998). For example, BC in the free troposphere can enhance its radiative forcing by trapping energy emitted from lower cloud layers. \nThe modeling-based studies on BC vertical distribution are particularly poor (Chen et al., 2022), creating a need to measure the vertical distribution of BC on a regional scale,from areas characterized by anthropogenic emissions from the ground to those characterized by long-range transport(Ramana et al., 2010). Among all the other methods, drones have recently gained popularity because of their high-cost efficiency, flexibility, and mobility. Besides comparing BC aerosol vertical distribution at an urban and a regional background site, this study also calibrates drone measurements using a 230-meter tower.
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(IN)DEPENDENCE OF AEROSOL ACTIVATION ON CLOUD POSITION
Zíková, Naděžda ; Pokorná, Petra ; Sedlák, Pavel ; Sokol, Zbyněk ; Ždímal, Vladimír
Five in situ campaigns focused on aerosol-cloud interactions were conducted at Mount Milešovka in the Czech Republic to gain more insight into aerosol activation and its dependence on meteorological parameters, mainly vertical air velocity and position within the cloud. The activated fraction was calculated from the difference of concentrations measured behind the whole air inlet and the PM2.5 inlet. The liquid water content (LWC) was calculated from visibility, cloud base position was estimated from ceilometer data. Vertical air velocity was estimated from cloud radar. No strong dependence was found between visibility and vertical velocity, suggesting that the clouds at the station are mostly of advection or inversion origin. Both visibility and LWC depend on the position within the cloud, with the highest LWC values found when the station was between 100 and 400 m above the cloud base, independently of the actual value.
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New particle formation measurement down to 1.2 nm at noak
Holubová, Adéla ; Zíková, Naděžda ; Ždímal, Vladimír
Atmospheric aerosols influence Earth’s climatic system and human health. Role of aerosols in climatic system still includes uncertainties strongly influencing model simulations (Zhao et al. \n2018). One of the uncertainties is caused by secondary aerosol formation and their consequent growth. Nucleation of aerosol particles is a process determined by presence of aerosol precursors in atmosphere and by ambient atmospheric conditions (Dada et al. 2017). \nSince new particle formation (NPF) events have been observed in many types of environment (Kulmala et al. 2004), we have focused on NPF events at background station in the Czech Republic, representative for central European region. In this study we investigate NPF process of aerosol clusters from 1.2 nm in size.\n
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Atmospheric aerosol and hydrometeors
Jüthner, Ludvík ; Zíková, Naděžda (advisor) ; Hůnová, Iva (referee)
This thesis examines the interactions between ultrafine and fine modes of atmospheric aerosol and precipitation episodes of rain, snow and drizzle. For the research were used data from the period 1.11.2018 to 30.4.2020 at the rural background station Milešovka. It was chosen a combination of a disdrometer together with a Scanning mobility particle sizer spectrometer (SMPS) for the data collection. Ten-minute averages were then used to determine the change in aerosol particle concentration during individual precipitation episodes and to calculate the scavenging coefficient. Then was calculated a Pearson correlation to determine the effect of raindrop size, rainfall intensity, temperature, relative humidity and wind speed on the decrease in aerosol concentration by individual hydrometeors. Finally, a cluster analysis of the air mass history was performed. An assessment of the change in aerosol particle concentration during each event showed that although all three selected hydrometeors contributed to the decrease in particle concentrations, only rain caused a decrease in all size classes (-5,7%). The result of the scavenging coefficient estimation further confirmed the higher success of rain, with a median coefficient of 6,62 x 10-4 s-1 . The atmospheric cleaning by rain then proceeded best between...

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