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Příprava databáze pro studii škálovacích fenoménů v ionosféře
Mošna, Zbyšek ; Šauli, Petra ; Santolík, Ondřej
The correct forecast of the state of the ionosphere requires understanding of all the effects which influence its behaviour as well as the extent of the relationships in the system. A convenient way how to analyse large data sets and describe the coupling or disconnection at various time scales is to study the scaling phenomena. For the computations of scaling properties of the processes that influence the ionosphere dynamics we have prepared a database of several characteristics that describe the coupling processes in the solar-magnetosphere-ionosphere system. This data are of sufficient length and sampling density to verify the presence or absence of links between the processes under study.
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Vyhodnocení nejistoty plošné předpovědi silných konvektivních srážek
Zacharov, Petr, jr. ; Řezáčová, Daniela
Extreme convective events have been studied with numerical weather prediction model LM COSMO (horizontal resolution of 2.8km) and radar data. An ensemble of 13 forecasts, which followed from modyfying initial fields, was created for two of analyzed events. Uncertainty in area-related quantitative precipitation forecast (QPF) was evaluated by fraction skill score (FSS) to quantify an ensemble spread and skill. The spread assesses a difference between a control forecast and ensemble member forecasts and the skill evaluates a difference between a precipitation forecast and radar derived precipitation. The uncertainty analysis shows an effect of forecast lead time and space scale as well as a sensitivity to the area structure of precipitation field. In this paper we summarize our first results dealing with the scale influence on the ensemble spread and skill.
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Nová diagnostika pomocí Thomsonova rozptylu pro tokamak COMPASS
Aftanas, Milan ; Bělský, Petr ; Böhm, Petr ; Weinzettl, Vladimír ; Brotánková, Jana ; Barth, R. ; van der Meiden, H.
The COMPASS tokamak, originally from UKAEA, Culham laboratory, U.K., will be reinstalled at Institute of Plasma Physics, Prague. The scientific programme is focused mainly on the investigation of the edge plasma region with high temperature and density gradients called pedestal. Many innovations will be done and new diagnostics have to be constructed. One of the key diagnostics is an incoherent Thomson scattering for measurements of electron temperature Te and density ne with a high spatial resolution. Several construction options are considered. In this paper a possibility of using a Nd:YAG laser in combination with a detection system based on Avalanche Photodiodes is discussed.
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Pole rychlosti a koncentrace v oblasti křižovatky
Kellnerová, Radka ; Jaňour, Zbyněk
The aim of this project is to investigate the influence of intersection configuration on spreading of contaminants from the vehicle traffic. Experiment was performed by physical modeling method. For crossroad in the shape of perpendicular X, we have measured the mean velocity and concentration field. The flow investigation has confirmed that within the area of corner vortexes occurs to the largest accumulation. Further in the canyon the concentration field is affected by developed vertical vortex and accumulation appears mostly on the leeward side.
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Fotochemie v klastrech a nanočásticích: systémy relevantní v atmosférické chemii a v biologii
Fárník, Michal
Influence of solvation on photodissociation of molecules is investigated in clusters produced in a molecular beam experiment. Photochemistry in three different systems is compared: (i) HBrArn and (HBr)n clusters, where the fragment does not react with the solvent and an effect of the fragment caging is observed, (ii) HBr(H2O)n system where chemical reaction occurs and a reaction channel is closed by the electronic interaction with the solvent. The practical relevance of the studied processes ranges from atmospheric chemistry to biology.
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