National Repository of Grey Literature 77 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
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...
The impact of covid-19 restrictions on carbonaceous aerosols at rural background site: importance of vertical distribution
Mbengue, Saliou ; Vodička, Petr ; Komínková, Kateřina ; Schwarz, Jaroslav ; Zíková, Naděžda ; Prokeš, Roman ; Suchánková, Lenka ; Julaha, Kajal ; Ondráček, Jakub ; Holoubek, Ivan ; Ždímal, Vladimír
In this study, EC and OC at 4 m elevation and EC at 230 m elevation showed a similar \nseasonal pattern with higher values in winter and lower values in summer. OC, measured \nat 230 m height showed an opposite behavior with slightly higher values in spring and \nsummer, probably related to the increased contribution of secondary organic carbon \n(SOC). Concentrations were generally higher at 4 m, where there was also a better \ncorrelation between EC and OC, suggesting a greater influence of local sources near the \nsurface.
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An Improved Method for Calculation of the Wet Particle Diameter and tha Kappa Parameters from the CCN Data
Wagner, Zdeněk ; Mishra, Gaurav ; Moravec, Pavel ; Zíková, Naděžda
The study of particle size distribution and hygroscopic growth is important for several reasons. Particle diameter is available experimentally, but the relationship of \nhygroscopic growth to cloud condensation nuclei (CCN) and AMS data can be modeled mathematically. In this paper, we present an improved algorithm for calculating the wet \nparticle diameter and the κ parameter that is faster, more accurate, and more reliable than the algorithm used by other authors.\n
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Dependence of aerosol activation on meteorological conditions
Zíková, Naděžda ; Pokorná, Petra ; Sedlák, Pavel ; Ždímal, Vladimír
Four intensive in-situ campaigns focused on aerosol-cloud interactions were performed in the autumn and spring months from Nov 2018 to Apr 2020 at Milešovka Mountain in Czechia to bring more insight into size-dependent aerosol activation and dependence on its origin for a wide variety of meteorological parameters. Most activated particles were larger than 100 nm, with a mode over 200 nm. For the description of the changes in the activation, no effect of photochemistry was found, in contrast, some dependence on relative humidity, temperature, wind speed, and liquid water content (LWC) proved to be useful. The strongest connection was found between activation and LWC. For LWC below 0.1 g/m3, in the LWC-limited regime, the LWC values and variables effecting the LWC were the main factors influencing the activation, while different parameters could have played a role at LWCs over 0.1 g/m3, in the LWC-independent regime.
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Physicochemical Properties and Origin of PM1 Measured at a Rural Background Site
Pokorná, Petra ; Zíková, Naděžda ; Vodička, Petr ; Lhotka, Radek ; Mbengue, Saliou ; Holubová Šmejkalová, A. ; Riffault, V. ; Ondráček, Jakub ; Schwarz, Jaroslav ; Ždímal, Vladimír
This study assesses the variability of organic aerosol (OA) sources monitored at the rural background site Frýdlant. Non-refractory PM1 was evaluated in two seasons of\n2021. The positive matrix factorization with the multi-linear engine was used to determine the sources of OA at Frýdlant site, with four factors resolved both in winter and\nsummer.
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Planetary Boundari Layer Effect on Vertical Transport of Black Carbon Concentration under Different Meteorological Conditions
Julaha, Kajal ; Zíková, Naděžda ; Mbengue, Saliou ; Ždímal, Vladimír
In the present study, we analyzed the impact of equivalent black carbon (eBC) aerosols at two different heights (4 m and 230 m) on the PBL height under different \nmetrological conditions such as clear sky, foggy (visibility ≤ 1km), and hazy days (visibility ≤ 8km during the non-fog day), high relative humidity, temperature, and \nobservational data, also, diurnal and seasonal variability was evaluated.
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A Seven-Years Based Characterization of Aerosol Light Scattering Properties at Central European Rural Site: Variability and Source Apportionment
Suchánková, Lenka ; Mbengue, S. ; Zíková, Naděžda ; Ondráček, Jakub ; Holubová Šmejkalová, A. ; Prokeš, R. ; Holoubek, I. ; Ždímal, Vladimír
The aim of this study is to focus on the temporal variations of light-scattering properties of aerosols at a rural background site in Central Europe. The total light scattering (σsp) and backscattering (σbsp) coefficients and associated calculated optical properties such as the Ångström exponent (SAE), the backscattering ratio (b), and the asymmetry factor (g), are characterized considering different time scales (annual, seasonal, monthly, or diurnal) based on long-term measurement. The optical properties were compared with meteorological conditions (fog, cloudiness), the concentrations of gaseous pollutants such as NOx and SO2 were inspected as well as potential sources of atmospheric aerosols. In addition, radiative forcing, and the influence of other meteorological conditions (e.g., height of planetary boundary layer), chemical composition and particle size distribution at the National Atmospheric Observatory Košetice (NAOK) are being further investigated to better understand the direct effects of aerosols on the local climate.
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Chemical composition and sources of atmospheric aerosols at the Frýdlant background station
Lhotka, Radek ; Pokorná, Petra ; Vodička, Petr ; Zíková, Naděžda ; Ondráček, Jakub ; Arora, S. ; Poulain, L. ; Hermann, H. ; Schwarz, Jaroslav ; Ždímal, Vladimír
This study assesses the variability of organic aerosol (OA) sources monitored at the rural background site Frýdlant. Non-refractory PM1 was evaluated in two seasons of\n2021. The positive matrix factorization with the multi-linear engine was used to determine the sources of OA at Frýdlant site, with four factors resolved both in winter and\nsummer.
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Ice nucleating particles in the atmosphere
Gaálová, Gabriela ; Zíková, Naděžda (advisor) ; Sedlák, Pavel (referee)
The production of clouds and precipitation in the atmosphere is greatly influenced by microscopic ice nucleating particles, acting in the process of heterogeneous ice nucleation as ice nuclei. Examining the properties and variations of ice nucleating particles concent- rations over time might help to better predict future changes to the climate. The aim of this thesis is to summarise the information about processes of homogeneous, but primarily heterogeneous ice nucleation where specific physical and chemical features of these particles are applied. In this thesis, the main aerosol sources of ice nucleating particles and their abilities to directly or indirectly influence the atmosphere and climate are described. The observational methods of the concentration of ice nucleating particles in the air are also pre- sented, while the structure of the cloud expansion chamber PINE, which was used to obtain data values representing the amount of ice nucleating particles in the Czech Republic, is also described in more detail. From the data set total average values and time dependen- cies, including daily and weekly cycle were calculated; the part of the data processing is the statistical evaluation and comparison of the results with other studies. Keywords: ice nucleating particles, nucleation, aerosol,...
Measurements of atmospheric aerosol on the top of Milešovka during the presence of fog versus during the absence of fog
Sedlák, Pavel ; Ziková, Naděžda
The paper describes the measurement of the aerosol particle size distribution during both the occurrence and absence of fog at the top of Milešovka.

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