National Repository of Grey Literature 9 records found  Search took 0.00 seconds. 
Short-term rainfall for hydrological modeling and design of small water management structures in the landscape
Kavka, P. ; Müller, Miloslav ; Strouhal, L. ; Kašpar, Marek ; Bližňák, Vojtěch ; Landa, M. ; Weyskrabová, L. ; Pavel, M. ; Dostál, T.
The aim of this methodology is to reduce the current knowledge deficit in the field of short-term rainfall variability and its application in hydrological modeling and design of small water structures and conservation measures within the catchment. The methodology defines six generalized short-term rainfall scenarios with specific temporal distribution of rainfall intensity. Next their variability related to their occurence frequency and spatial distribution accross Czech Republic is presented. These scenarios were derived from the 10-years time series of radar rainfall measurements adjusted with the daily totals from ground gauging network.
Possibilities of Using of Remote Detection Data for Convective Storms Intensity Nowcasting
Valachová, Michaela ; Žák, Michal (advisor) ; Bližňák, Vojtěch (referee) ; Simon, André (referee)
Title: Possibilities of Using of Remote Detection Data for Convective Storms Intensity Nowcasting Author: Michaela Valachová Department: Department of Atmospheric Physics Supervisor: Mgr. Michal Žák, Ph.D., Department of Atmospheric Physics Abstract: Evolution of 60 isolated convective storms from 2016 and 2017, which formed in the region of Central Europe, is studied by means of multi-sensor observations. According to the reports from the European Severe Weather Da- tabase, two categories of storms are classified: severe and non-severe. Based on radar, lightning and satellite measurements, trends of storm characteristics are analyzed to ascertain their typical behavior. Lightning stroke rates and their change could well warn about the ability of the storm to become severe, therefore a Lightning jump algorithm was proposed within this work. From individual case studies follows that methods of remote sensing offer comprehensive information about convective storm life-cycles. In order to objectively determine crucial variables for estimating the storm se- verity, logistic regression models and regularized regressions (elastic net) are employed. In total 53 variables from the first 30, 60 and 90 minutes of the moni- tored storm lifetime are used to show their predictive skill. Results of the models indicate...
Testing of products generated from Meteosat satellite (MSG) images in synoptic praxis
Pokorný, Michal ; Žák, Michal (advisor) ; Bližňák, Vojtěch (referee) ; Dejmal, Karel (referee)
First part of the thesis introduces possibilities of depicting of the data provided by the MSG (Meteosat Second Generation) satellite. Different color combinations (RGB - red, green, blue) description made by the basic channels combination follows. The main part of this thesis is focused on T-re profiles (T - temperature, re - effective cloud particle radius). The analysis of profiles of temperature versus the effective radius of cloud particles shows the vertical distribution of the effective particle size in clouds. The profiles are computed and constructed from the satellite retrieved data and they show graphically the distribution of cloud particles and indirectly represent the severity of the developing storms. Forecasting and predicting dangerous phenomena such as hailstorms or tornados that occur in severe storms is the main objective of the technique. This nowcasting tool was tested in Central Europe and the end of this thesis presents the results of the testing.
Radar-based summer precipitation climatology with respect to orography in the Czech Republic
Bližňák, Vojtěch ; Müller, Miloslav ; Kašpar, Marek
The aim of this work is climatological analysis of 10-year series of summer precipitation derived from radar and precipitation\nmeasurements in high spatial and temporal resolution. The definition of the summer season is related to the fact that\nthis part of the year represents the most humid period with the most probable occurrence of extreme rainfall events.\nParticular attention is paid to spatial distribution of average seasonal and maximum 30 min - 24 h\ntotal precipitation in the middle and mountainous locations. Part of the study is also the characteristic of daytime precipitation with respect\non the Czech Republic (Czech Republic).\nDespite the relatively short period of 10 summer seasons, the present work provides new and more detailed knowledge\nthe spatial and temporal distribution of the mean and maximum sums of summer precipitation. Within climatological analysis\nis used glide sums of precipitation that are better able to capture absolute maxima in time series,\nwhich gives room for more precise calculation of frequency of occurrence, respectively. N-year rainfall sums in sub-days\nscale. Calculated climatological characteristics will be further refined in the future with prolonged time\nmeasurement.
Interests from the 110-year observation series at the meteorological observatory Milešovka
Chládová, Zuzana ; Bližňák, Vojtěch
The 110-year-old series from the Milešovka Observatory contains many interesting information not only from a meteorological point of view, but also from the point of view of historical and social events that to measure direct effects such as short-term interruption of measurements during World War I due to the lack of coal (Figure 3), measurement failures in the period after the mobilization in 1938 and others.
Tornadoes in the Czech Republic
Šáfrová, Martina ; Zacharov, Petr (advisor) ; Bližňák, Vojtěch (referee)
The Bachelor work is devoted to the task of occurance the tornado over our territory. The goal of the work is on the basis of available czech and foreing literature to make acquaintance with the pesent physique knowledge of organised convection rise and tornado formation. The second goal was to show overview of tornado rise during the last ten years and introduct several tornado rise studyings. There were calculated precursors of strong convection for these rise studyings and there values were discussed in the work. Key words: tornado, convection, precursors of convection, vorticity
The exploitation of remote sensing for the analysis and progress of rainfalls
Bližňák, Vojtěch ; Sokol, Zbyněk (advisor) ; Setvák, Martin (referee) ; Pešice, Petr (referee)
The thesis is divided in two parts. The first part deals with the areal distribution of short-term convective rainfalls with regard to the influence of altitude. Precipitation estimates based on combination of rain gauge and radar data are used for this purpose. Statistical tests proved that the areal distribution of hourly convective rainfalls does not depend on altitude. Besides data containing precipitation events only, all measured data were statistically analysed regardless of the fact whether precipitation occurred or not. In this case it was found out that the relationship between hourly rainfall totals and altitude depends on the considered threshold of rainfall totals. When all data were considered, i.e. a threshold value was set to zero, an increase of rainfall totals well correlated with altitude. The dependence slowly disappeared with an increasing threshold. The areal distribution of 6 hour rainfall totals proved higher values in the area of south Bohemia. The most frequent synoptic patterns were northwest cyclonic situations (NWC) and cyclone over the Central Europe (C). The second part of the thesis is focused on satellite data exploitation, as measured by meteorological satellite Meteosat Second Generation, for convective precipitation estimates. The Convective Rainfall Rate (CRR) algorithm,...
The analysis of short-term rainfalls and their link to the orography of the Czech republic
Bližňák, Vojtěch
The diploma thesis deals with the dependence of short-term intensive precipitations on the altitude of the Czech Republic. Data from the warm period of the year were used, it means from 1st April to 30th September, because there are the most frequent occurrence of the convective phenomena, which are the cause of the intensive precipitations. It was used data of 3 years: 2002, 2004 and 2005. These data represent the results of radar's measurement from weather radar Network CZRAD (radars Skalky, Brdy), for the year 2005 it was used also data corrected according to the rain gauges network (adjustment). The emphasis is placed on the study of 1-hour precipitation amounts, their comparison with results of 3-hours, 6-hours, 12-hours and 24-hours precipitation amounts and the interpretation in graphs, tables and cartograms. The analyses of 1-hour precipitation amounts showed very slow trend from the lowlands till the altitudes of 600 - 800 m a. s. l. The precipitation amounts descended towards the mountains. During longer precipitations the maximum values were situated mostly in the altitude 500 m a. s. l., whereas the precipitation amounts rose to this altitude, upward descended. Maxima are mostly situated in piedmont windward slopes. It was also used daily rainfall totals from the same years, which...

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