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Utilization of Radar Echo Extrapolation for Quantitative Precipitation Forecast
Frolík, Petr ; Novák, Petr (advisor) ; Žák, Michal (referee)
At present time weather radar data are essential for national meteorological services. Utilization of this data for quantitative precipitation forecast and severe weather prediction for short period (nowcasting) becomes more and more common. Increasing interest for quantitative precipitation forecasts can be noticed in hydrological applications, where it can give early warning on flash floods and can improve large scale precipitation forecasts. This paper verifies usability of COTREC nowcasting method based on extrapolation of radar echo for quantitative precipitation forecast. Quality of COTREC forecast up to 3 hours was investigated on data from 1.4.2006 to 30.9.2006. Comparison of COTREC method with Aladin NWP model forecasts was also made. Hourly mean precipitation estimates on catchments were chosen for comparison because of verification focused mainly on utilization of the forecasts in hydrological applications. Forecasted precipitation estimates were compared with optimal operationally available precipitation estimate - adjusted radar estimate combined with available raingauge measurements.
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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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Forecasting of lightning using numerical weather prediction model ALADIN
Němec, David ; Žák, Michal (advisor) ; Kyznarová, Hana (referee)
This thesis deals with modelling and forecasting lightning activity using NWP model ALADIN. The first part briefly describes physical processes involved in lightning initia- tion and principles of lightning detection. This part also outlines some basic principles of modelling deep convection and phase changes in ALADIN and continues with descrip- tion of diagnostic scheme for forecasting of lightning activity. The main part describes calibration of the scheme as well as compares forecast with measured data from light- ning detection system LINET. Both time and spatial distributions are considered. This part also contains analysis of scheme behaviour during six days with significant lightning activity over Czechia. 1
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Testing of produkts generated from Meteosat satellite (MSG) images in synoptic praxis
Pokorný, Michal ; Žák, Michal (advisor)
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.
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Utilization of Radar Echo Extrapolation for Quantitative Precipitation Forecast
Frolík, Petr ; Novák, Petr (advisor) ; Žák, Michal (referee)
Title: Utilization of radar echo extrapolation for quantitative precipitation forecast Author: Petr Frolík Department: Department of Meteorology and Enviroment Protection Supervisor: RNDr. Petr Novák, PhD., ČHMÚ Supervisor's e-mail address: petr_novak@chmi.cz Abstract: At present time weather radar data are essential for national meteorological services. Utilization of this data for quantitative precipitation forecast and severe weather prediction for short period (nowcasting) becomes more and more common. Increasing interest for quantitative precipitation forecasts can be noticed in hydrological applications, where it can give early warning on flash floods and can improve large scale precipitation forecasts. This paper verifies usability of COTREC nowcasting method based on extrapolation of radar echo for quantitative precipitation forecast. Quality of COTREC forecast up to 3 hours was investigated on data from 1.4.2006 to 30.9.2006. Comparison of COTREC method with Aladin NWP model forecasts was also made. Hourly mean precipitation estimates on catchments were chosen for comparison because of verification focused mainly on utilization of the forecasts in hydrological applications. Forecasted precipitation estimates were compared with optimal operationally available precipitation estimate - adjusted radar...
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Possibilities of Using of Remote Detection Data for Convective Storms Intensity Nowcasting
Valachová, Michaela ; Žák, Michal (advisor)
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...
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Using of climate satellite data for study of weather circulation type influence on selected meteorological parameters
Kotek, Jiří ; Žák, Michal (advisor) ; Šrámek, Jan (referee)
Cloudiness and solar radiation affect the Earth's energy and water cycle and spa- tial distribution of these parameters is also connected to the atmospheric pressure field and atmospheric circulation. This thesis starts with a short overview of remote sensing of the atmosphere, the EUMETSAT organisation and its section CM SAF which focuses on the uses of satellite data for climate monitoring. Next is a description of cloud and ra- diation products used in this thesis. Daily means of these products in the Czech Republic are then used to calculate mean values, trends and anomalies for the whole time series. Obtained values are compared based on the weather circulation type using the Brádka classification. 1
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Lightning activity in the regions of MSC over Czechia
Arnoštová, Michaela ; Žák, Michal (advisor) ; Valachová, Michaela (referee)
Title: Lightning activity in the regions of MCS over Czechia Author: Michaela Arnoštová Department: Department of Atmospheric Physics Supervisor: Mgr. Michal Žák, Ph.D., Department of Atmospheric Physics Abstract: This bachelor's thesis deals with lighting activity and its detection in mesoscale convective systems (MCS) over the Czech Republic and adjacent areas. The first part describes the formation and development of MCS, electrical charge distribution inside clouds, types of lightning and their detection. The second part is devoted to five specific MCS that occurred in different time periods. Data of lightning detection network (LINET) are used to describe the characteristics of lightning, especially their temporal and spatial development, occurrence of different types of lightning and development of their current amplitude and altitude. Keywords: Mesoscale convective system, lightning activity, lightning detection
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Study of Urban Heat Island with using of remote sensing investigations
Doležalová, Anežka ; Žák, Michal (advisor) ; Huszár, Peter (referee)
Modern times bring considerable urbanization which represents the development and extension of cities. An urban environment is very different in structure from the rural one and the natural landscape. The differences are shown in various types of climatic observations and they also lead to a phenomenon called Urban Heat Island. The city appears as an island with higher temperature compared to the surrounding rural areas. Eumetsat satellites called MFG and MSG with the MVIRI and SEVIRI instruments are used for the analysis of SUHI, the measurement of which is processed by the application of various algorithms. 1
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