Národní úložiště šedé literatury Nalezeno 19 záznamů.  1 - 10další  přejít na záznam: Hledání trvalo 0.01 vteřin. 
PROCESSING OF THE DATA MEASURED WITH CLOUD CONDENSATION NUCLEI COUNTER IN YEAR 2020 FOR SUBMISSION TO EBAS DATABASE
Moravec, Pavel ; Jindra, Tomáš ; Wagner, Zdeněk ; Ždímal, Vladimír
Aerosol particles in the atmosphere that allow water vapor to condense and form cloud droplets are called Cloud Condensation Nuclei (CCN). Elevated concentrations of CCN tend to increase the concentration and decrease the size of cloud droplets. This can lead to suppression of precipitation in shallow and short-lived clouds and to greater convective overturning and more precipitation in deep convective clouds, Rose et al.(2010). The response of cloud properties and precipitation processes to increasing anthropogenic aerosol concentrations represents one of the largest uncertainties in the current understanding of climate change. One of the fundamental challenges is to determine the ability of aerosol particles to act as CCN under relevant atmospheric conditions. Knowledge of the spatial and temporal distribution in the atmosphere is essential to incorporate the effects of CCN into meteorological models of all scales, Huang et al. (2007). Long-term CCN measurements are performed at aerosol monitoring sites such as those forming ACTRIS (Aerosols, Clouds, and Trace Gases Research Infrastructure) network. Measured data are then submitted to the EBAS database, where they are available for the other ACTRIS researchers. In this paper, we present our experience with the processing of the data measured with CCNC for submission to the EBAS database. The data prepared for submission to EBAS from year 2020 are also presented.
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The effect of meteorology and aerosol size distribution on light scattering properties at a rural background site in Central Europe
Suchánková, Lenka
The aim of this study is to characterize the light scattering properties of aerosols at the rural background site National Atmospheric\nObservatory Košetice (NAOK; 49°34’20.787”N, 15°4’48.155”E) in Central Europe, namely the coefficients of total light scattering (σsp) and backscattering (σbsp), the Ångström exponent (SAE), the backscattering ratio (b), and the asymmetry factor (g), with special attention to the influence of meteorology and aerosol size distribution on these properties. We measured σ𝑠𝑝 and σ𝑏𝑠𝑝 at three wavelengths (450, 550, and 700 nm) using the Integrating Nephelometer TSI 3563 (PM10 inlet). The measurements were performed from August 16, 2012 to December 31, 2019.
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Ambient organic aerosol origin at rural background site in the Czech Republic
Lhotka, Radek
Atmospheric aerosols (AA) are ubiquitous particles in the atmosphere that influence the Earth’s climatic system, environmental interactions, and human health. Among AA, great interest is dedicated to organic aerosols (OA) since it can represent from 20 to 90% of total submicron mass. Source apportionment of OA at background sites is one of the important tasks of current air quality protection.
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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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Závislost aktivace aerosolu na meteorologických podmínkách
Zíková, Naděžda ; Pokorná, Petra ; Sedlák, Pavel ; Ždímal, Vladimír
V šesté hodnotící zprávě IPCC byla nejvyšší hodnota aerosolového forcingu připsána tzv. nepřímému aerosolovému efektu, tedy interakci mezi atmosférickým aerosolem (AA) a oblačností (Arias a kol., 2021). Tato interakce závisí na množství aktivovaných oblačných jader, což je veličina, kterou je náročné měřit i modelovat. Proto byl zkoumán vliv velikostně diferencované aktivace AA na meteorologických veličinách a jevech.
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NMR Aerosolomics Study of Water-Soluble Organic Compounds in Size-Resolved Particulate Matter
Horník, Štěpán ; Vodička, Petr ; Pokorná, Petra ; Schwarz, Jaroslav ; Ždímal, Vladimír ; Sýkora, Jan
Organic aerosols (OA) account for a significant fraction (10 – 90%) of atmospheric particulate matter (Hallquist et al., 2009). The composition of organic aerosols is very complex and is usually characterized by their water solubility. Water-soluble organic compounds (WSOC) constitute a large fraction of OA (10 – 80%) and consist of chemical species containing oxygenated functional groups such as hydroxyl, carboxyl, or carbonyl groups. NMR spectroscopy represents an alternative to commonly used techniques (gas chromatography-mass spectrometry, liquid chromatography-based techniques) for WSOC analysis. Our recently introduced method, called NMR aerosolomics, allows quantitative analysis of dozens of individual compounds from different aerosol samples. An important part of the characterization of aerosols is their classification by particle size. The analysis of individual compounds in the size-resolved fractions of the WSOC class has been performed only in a few studies that focus mainly on a particular subclass of compounds or use multiple analytical techniques.
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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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