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EUMETSAT SAFNWC (SAF in Support to Nowcasting and Very Short-Range Forecasting) and its applications in meteorology
Šťástka, Jindřich ; Setvák, Martin (advisor) ; Bednář, Jan (referee)
In the present work we study products for processing data from weather satellites named SAFNWC (SAF in Support to Nowcasting and Very Short-Range Forecasting). SAFNWC is one of the most important of EUMETSAT SAFs (dedicated centers of excellence for processing satellite data), delivering both - complex software modules, as well as operational products delivered in real-time to the end users. Main goal of the thesis is to prepare an overview of presently available software modules and their operational products, with emphasis on the MSG data. Second goal, depending on available software modules and support data resources, is to experimentally implement some of the modules in the Czech Hydrometeorological Institute (CHMI).
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Broadband radiation scheme fully interacting with clouds
Mašek, Ján ; Brožková, Radmila (advisor) ; Bednář, Jan (referee) ; Kubátová, Brankica (referee)
The parameterization of radiative transfer is a part of numerical weather prediction and general circulation models that is both essential and computationally very expensive, and is therefore subject to neverending compromises between accuracy and computational cost. The present thesis offers an improvement to the existing broadband radiation scheme by revising its critical components - gaseous transmissions, cloud optical properties, and calculation of internal longwave exchanges. The accuracy of the fullspectrum broadband approach is thus raised to the level required for the short range numerical weather forecast. The intermittent update of broadband gaseous transmissions is introduced as a new component, reducing computational cost while preserving the full cloudradiation interaction. The scalability of longwave computations is ensured by adopting the net exchanged rate decomposition with bracketing, improved by an intermittently applied selflearning algorithm determining the interpolation weights. It has been demonstrated that under conditions of operational weather forecasting, this developed scheme is fully competitive with the mainstream approach, due to the improved error balance between the...
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Study of links between biogenic VOC emissions and concentration of tropospheric ozone
Zemánková, Kateřina ; Brechler, Josef (advisor) ; Bednář, Jan (referee) ; Braniš, Martin (referee)
Title of dissertation: Study of links between biogenic VOC emissions and concentration of tropospheric ozone Kateřina Zemánková, 2010 Dissertation directed by: doc. RNDr. Josef Brechler, CSc. Dept. of Meteorology and Environment Protection, Faculty of Mathematics and Physics, Charles University in Prague Presented work focuses on influence of volatile organic compounds from biogenic sources on concentration of tropospheric ozone. Volatile organic compounds (VOC) play an important role in the tropospheric chemical system. Together with oxides of nitrogen they form two major components of reactions leading to low-level ozone formation. Volatile organic compounds are emitted into the atmosphere from an- thropogenic as well as from biogenic sources. In global, VOCs from natural sources are approximately ten times higher in magnitude than those of anthropogenic origin. Biogenic VOCs are emitted from various sources among which the forest ecosystems predominate. Group of VOCs of natural origin comprises wide range of chemical com- pounds. Those emitted in highest concentrations are isoprene and group of monoter- penes. Emissions of biogenic VOCs from the area of the Czech Republic have been es- timated based on the high resolution land cover data giving detailed information of sigle tree species...
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Atmospheric blocking and its climatology with respect to used detection criteria
Dragula, Adam ; Žák, Michal (advisor) ; Bednář, Jan (referee)
Atmospheric blocking is a synoptic-scale weather phenomenom, which might have significant economic and social impacts on account of a correlation with severe weather features, such as heat waves, persistent drought periods or floods. Several objective detection methods were developed in order to study blocking events. These methods are described and qualitatively discussed in the review part of the thesis. Chosen detection methods were subsequently used for an analysis of basic blocking characteristics over European region. Time evolution of blocking frequency and blocking duration is the key part of results, focusing on possible correlation of these characteristics with the global temperature rise within climate change.
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Electron cryo-microscopy techniques in biological research and nanotechnologies
Mistríková, Veronika ; Bednár, Jan (advisor) ; Nebesářová, Jana (referee) ; Benada, Oldřich (referee)
Preparation of biological samples for transmission electron microscopy is not a trivial task. The samples must withstand a vacuum environment present inside a microscope, and it is often necessary to use non-physiological procedures for their processing. These procedures usually involve aldehyde-based fixation, replacing water with alcohol (i.e. dehydration/substitution), and embedding into a resin, which creates support for the subsequent preparation of thin sections that can be placed into the microscope. In the last decade, the method of cryo-fixation (vitrification) using ultra-fast high-pressure freezing followed by freeze substitution and low-temperature resin embedding gained a dominant position in the cell biology research. In this way, a range of biological samples with a thicknesses up to several hundreds of micrometers was successfully vitrified to a state that was closely related to their in vivo structures. The cryo-fixation of isolated biological objects (with a limited thickness up to several micrometers) is possible in a thin layer of vitrified water by plunge freezing at ambient pressure. In combination with electron cryo-microscopy, this method has become the most effective and fundamental principle for the high-resolution studies and image analysis of fully hydrated samples...
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Study of tropospheric chemistry using regional climate model RegCM4 and chemistry transport model CAMx
Bartík, Lukáš ; Huszár, Peter (advisor) ; Bednář, Jan (referee)
The subject of this diploma thesis is study of the impacts of different implementations of turbulence and convection in the Regional Climate Model (RegCM, version 4.6) on the ability to predict the chemical pollution of the troposphere in Europe, which was simulated by the chemical transport model CAMx (Comprehensive Air quality Model with extensions, version 6.50) driven by RegCM meteorology using offline coupling of theese two models. Thesis also includes a brief description of the tropospheric chemistry, a discussion of the influence of meteorological conditions on changes in pollutant concentrations in the troposphere, a brief introduction to the regional climate modeling, a description of both models and method of their coupling. The main focus of the thesis is the analysis of the impacts of different parameterizations in RegCM model simulations on some climatic elements, validation of air temperature and precipitation, analysis of the impacts of changes in driving meteorology on ozone, nitrogen dioxide, sulfur dioxide and fine aerosol, validation of model concentrations of these pollutants with measurements at rural monitoring stations and comparison of column concentrations of nitrogen dioxide with satellite measurements.
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