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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.
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Contemporary possibilities of atmosphere lightning detection
Nettl, Tomáš ; Žák, Michal (advisor) ; Pišoft, Petr (referee)
The aim of this thesis is to make a survey about posibilities of detection atmosferic discharges, describe their principles and properties. The other aim of thesis is comparing the systems CELDN and LINET. These two systems cover the area of Czech Republic. The first part of this work concerns of basic characteristic of flashes and electric properties of the atmosphere. The basic model of air discharges distribution in a storm and an electric field around is mentioned. Then the thesis describes the basic flash detection systems and the methods of detection.The end of the work describes systems covering Czech Republic - CELDN and LINET. Also basic characteristics of these systems derived from real data are discussed.
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Climate characteristics of higher atmospheric levels
Kuchař, Aleš ; Pišoft, Petr (advisor) ; Žák, Michal (referee)
This work investigates the climatic characteristics of the upper atmosphere. The characteristics that were analyzed include air temperature, speed and direction of the zonal wind, geopotential height and total column of ozone or its mixing ratio in the individual levels of pressure. Data from projects NCEP/NCAR and ERA-40 reanalysis were used for these purposes. The data are present in a graphic form, particularly in the average monthly maps during 1978−2007 for the first one and during 1978−2002 for the second one with azimuthal projection for each hemisphere for the levels of 300, 100, 10 and 30 hPa. The results obtained are described and interpreted by a research of available literature.
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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...
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Visibility at the Praha Ruzyne airport
Kusáková, Kateřina ; Žák, Michal (advisor) ; Pišoft, Petr (referee)
The goal of this bachelor thesis is to show the importance of visibility in flight operations. There are settled minima of visibility for each process, which must be achieved. Visibility has its own daily range, which is closely connected with solar radiation. Its also connected with a vertical structure of atmosphere, direction and speed of wind and current weather conditions. Visibility achieves its lowest values during intensive precipitations and in a fog. Mainly because of an appearance and lasting of a fog, there are compilations at the airport and very often a special procedures must be taken for an organization of flight operations. An appearance and lasting of a fog has a big influence on flight operations and that is why I pay an attention to this in my work. I concentrated myself not only on the daily range of visibility and its dependency on the direction of a wind, but on conditions of appearance and ending the fog as well.
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Precipitation nowcasting for the warm part of the year
Mejsnar, Jan ; Sokol, Zbyněk (advisor) ; Jaňour, Zbyněk (referee) ; Žák, Michal (referee)
Current precipitation nowcasting systems primarily use the extrapolation of observed radar reflectivity. I used the extrapolation and studied limits of the forecast using the concept of the decorrelation time (DCT). I used data from two radars covering the territory of the Czech Republic from warm parts of four years and calculated DCT in dependence on several selected conditions describing the state of the atmosphere. I found that the mean DCT for the extrapolation is 45.4 minutes. On average the increase of the DCT in comparison when the persistence forecast is employed is 13.4 minutes. However, in dependence on current conditions the DCT may increase or decrease in more than 40 %. I also explored time evolution of the DCT during two storm events. I found that the DCT may significantly change in time, which is the consequence of changing character of the atmosphere during the storm development.
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Tropical cyclones - what do we know about them and how can they be forecasted?
Rulfová, Zuzana ; Žák, Michal (advisor) ; Pišoft, Petr (referee)
Nazev prace: Tropicke cyklony - co o nich dnes vime a jak je unu'me pfedpovidat Autor: Zu/aua Rnlfova Katedra (ustav): Kaledva meteoiologie a oclnaiiy prostfedi Vedonci bakalafske pnice: Mgr. Michal Zak, Ph.D. e-mail vodonciho: Midial.Zak'J'Tnff.cimi.cz Abstrakt: Talc* prace shrnuje soueasne inforniaee o /ivuUiini cA'kln tropicke cyklouy a jejich ucincicli na mofi a pri dcjsazeni pcviiiny. Json x,d.e popsany iiejcastf\jsi oblasti vyskytu, iejicli poimciiiovaiii v jediiotlivych oblastech a. jejich klaaifikaco podlo in- ttnrxity. Dale u1)sahuic sledovaci a pfedpovedni inetody a jejich uspcsnost. Na konci pracc je uvcden prcliltxl vyzna.iunych iropickych cykloii. Klicova slova: tropicka cyklony, cyklogencze. puzorovam, pfedpovod' Title: Tropical (.cyclones - what, do \\v know about them and how can they be fore- casted? Author: Zuzana Rnlfovd Department: Tho Department of Meteorology and Environment. Protection Supervisor: Mgr. Alichnl Zak, Ph.D. Supervisor's e-mail address: Michal.Zak^mfi'.cnni.c/, Abstract: This thesis summarizes the recently information about life cycle oftropical cyclone and its effects out at sea. and before and after landfall. There are described the most common areas of occurrence ot tropical cyclones, their naming in these areas and their intensity classifications. Then this thesis...
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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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