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Areal extremity of windstorms in the Czech Republic
Polášek, Jan Ferdinand ; Kašpar, Marek (advisor) ; Pop, Lukáš (referee)
Areal extremity of windstorms in the Czech Republic Abstract This thesis deals with the extremeness of events with strong winds in the Czech Republic in the period from 1961 to 2009. The first part is dedicated to the principles of air flow dynamics and to wind climatology. The second part describes theoretical distributions used for evaluating the extremeness of wind speed and presents various computation methods of distribution parameters and interpolation methods of converting point data to spatial information. At the end of this part, two modern indices are introduced: WEI (Weather Extremity Index) and SSI (Storm Severity Index) which use return periods and wind speeds for evaluating the extremeness of windstorms, respectively. The third part contains an application of the methods to the pre-processed data from meteorological stations. The fourth section presents the files of 50 most extreme and 50 seasonally most abnormal windstorms selected by both indices which determine in different ways the extremeness, the affected area and duration of each event. The spatial and temporal aspects of the events are discussed as well, along with their seasonal and interannual variability and causal synoptic conditions. Among extreme wind events, most of them are synoptic scale windstorms related to great horizontal...
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Areal extremity of windstorms in the Czech Republic
Polášek, Jan Ferdinand ; Kašpar, Marek (advisor) ; Pop, Lukáš (referee)
Areal extremity of windstorms in the Czech Republic Abstract This thesis deals with the extremeness of events with strong winds in the Czech Republic in the period from 1961 to 2009. The first part is dedicated to the principles of air flow dynamics and to wind climatology. The second part describes theoretical distributions used for evaluating the extremeness of wind speed and presents various computation methods of distribution parameters and interpolation methods of converting point data to spatial information. At the end of this part, two modern indices are introduced: WEI (Weather Extremity Index) and SSI (Storm Severity Index) which use return periods and wind speeds for evaluating the extremeness of windstorms, respectively. The third part contains an application of the methods to the pre-processed data from meteorological stations. The fourth section presents the files of 50 most extreme and 50 seasonally most abnormal windstorms selected by both indices which determine in different ways the extremeness, the affected area and duration of each event. The spatial and temporal aspects of the events are discussed as well, along with their seasonal and interannual variability and causal synoptic conditions. Among extreme wind events, most of them are synoptic scale windstorms related to great horizontal...
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Measures of extremity in meteorology
Polášek, Jan Ferdinand ; Kašpar, Marek (advisor) ; Pecho, Jozef (referee)
Measures of extremity in meteorology Abstract This work deals with the methods of extremity quantification of meteorological variables and weather events. The first part is dedicated to the expression of variables by generalized extreme value distribution (GEV) and presents various computation methods of distribution parameters. The second part is dedicated to the extremity of wind storms, heat waves, droughts and heavy precipitation. The third part contains the application of the method based on the order of values and GEV distribution. We evaluate the extremity and abnormality of high daily mean temperatures at the station Milešovka and in the reanalysis ERA-40 and NCEP/NCAR for the grid point representing the Czech Republic. It is shown that the days with positive abnormality of temperature occur more frequently in the warm half-year. The method based on the order of values underestimates the return period of temperature extremes in most cases in comparison with the method based on the GEV distribution. The method based on the GEV distribution is sensitive to various input data. The design values for the station Milešovka increase with the return period more rapidly than reanalysis design values. Keywords: extremity, GEV function, Milešovka, reanalysis, temperature extreme, return period
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