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Validation of atmosphere prediction model in meso-scale
Mejstřík, Tomáš ; Žák, Michal (advisor) ; Řezáčová, Daniela (referee)
In this thesis, we are aimed at various physical principles of convective parametrization. First, traditional parametrization schemes are described. This schemes are based on hypothesis of quasi-equilibrium between large-scale processes and convective activity and suggestion about negligible mesh fraction of convection in grid-box. But, passing to resolution in the range below 10 km, the deep convection si partly subgrid, partly resolved. A new generation of prediction with high horizontal resolution is now introduced. This model has new prognostic convective scheme with new description of interaction between convective mass transport and microphysical computation of clouds and precipitation. A prognostic scheme has been used for the vertical velocity of udraft and downdraft and more elaborate microphysics, include effect of autoconversion, evaporation and sedimentation of precipitation. These models are expected to forecast many atmospheric events much more precisely (e.g. strong convection). Validation of model in experiments at different resolutions is the main task of this work. Comparsion of new developed model with model currently used, sensitivity study of new components, are presented.
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Specifics of climate of Prague and its relation to air pollution
Hošek, Jiří ; Sládek, Ivan (advisor) ; Žák, Michal (referee) ; Prošek, Pavel (referee)
I l::r,iduction -: _-::r: ;.inrate is an important part of life of rising number of people and it is* .." ř: :-': :-: ..\:lh increasing intensiý. Large cities have their specific mesoclímate that is.--l'.--.: :'.::ll1' by higher air temperature and lower humidiý. The reason is_:- '- .i..-. :=lermeab'e surťace, for which there is rapid runoff of precipitation, and:. .: : -::=-::-s. rvhich causes the ciý to absorb heat during the day and generate it during* : !-- l:: ::ler characteristics ofthe urban climate -.Ť: - iš::]:-\ of heat, increased surface roughness #;:Tffi:":''::".n1:I1*::' ř -'! .: :::]'.:ence on the temperafure and wind Íield over the urban area. --: .: of this work was to assess statisticar characteristics of wind field and urbanj :- :-: :::rerature on the area ofprague and its relation the air potution. The first step'- :ii-':::'-n and verification ofsurface wind field over the area ofprague usrng a::-.*:1 :-.ťel. Furthermore, other variables were calculated such as mixing length and: L' "' -;tor' rvhich are connected to the air pollution. The wind field calculation was' -.: :i Lisessm.nt of heat budget of built-up urban suďace. For that purpose' a. :j::.]:: s;heme rvas applied, which is capable to treat very complex suďace of the city. In:; ::' :::1 0f the work' the relation between...
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Study of the properties of cement concrete at high temperatures
Žák, Michal ; Sitek,, Libor (referee) ; Bodnárová, Lenka (advisor)
This diploma thesis is focused on behavior of cement concrete at high temperatures. The theoretical part describes processes, which take place in concrete at thermal loading and effect of this thermal load to mechanical and physical properties of concrete. Also there was described recommendation for testing physical and mechanical of concrete at high temperatures according to RILEM TC. In experimental part mixes were made with greywacke aggregate, amphibolite aggregate and with the addition of polypropylene fibers or cellulose fibers. In these mixes was determined the effect of high temperatures on the density of concrete, compressive strength of concrete and thermal strain of concrete. Further there was tested addition of 2 kg/m3 polypropylene fibers to concrete with basalt aggregate and siliceous aggregate and influence of these fibers to density of concrete, compressive strength of concrete and dynamic modulus of elasticity.
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Studying the behavior of concrete at high temperatures
Žák, Michal ; Sitek,, Libor (referee) ; Bodnárová, Lenka (advisor)
This bachelor's thesis is focused on behavior of concrete at high temperatures. The theoretical part describes processes, which take place in concrete at thermal loading and further there was described testing of concrete at high temperatures. Next there was described influence of high temperatures on each component of concrete and design of appropriate components for concrete exposed to high temperatures. In experimental part mixes was made with greywacke aggregate, amphibolite aggregate and with the addition of polypropylene fibers. In these mixes was determined the effect of high temperatures on the density of concrete, dynamic modulus of elasticity of concrete and compressive strength of concrete.
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Statistical Analysis of Temperature and Precipitation Time Series in the Czech Republic in Period 1961-2008
Helman, Karel ; Pecáková, Iva (advisor) ; Čermák, Václav (referee) ; Žák, Michal (referee)
The present dissertation deals with an analysis of monthly time series of average temperatures and precipitation sums recorded at 44 sites in the Czech Republic over the period of 1961--2008. The main research purpose is to acquire deeper knowledge of regularities in the climatic time series development, using an appropriate set of statistical methods. A secondary objective is to search and find correlations between the research outcomes and basic geographic coordinates (altitude, longitude and latitude) of particular measurement stations and comparing all the results achieved for the selected climatic elements. There are two major contributions of this work. In the first place, it presents new knowledge in the field of climatic time series, particularly in connection with the strength and development of their seasonal component, further for instance analysing the relation between the distribution of a residual component and the geographic coordinates of the measurement stations. Another contribution lies in an extensive application of statistical methods of climatic time series analysis. Several types of methods were used, having employed both widely and rarely applied statistical tools (linear trends analysis and Box-Jenkins methodology respectively) as well as those used for the very first time (moving-seasonal time series).
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