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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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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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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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Variability of the Brewer-Dobson Circulation
Kupčihová, Zuzana ; Pišoft, Petr (advisor) ; Kozubek, Michal (referee)
The middle atmosphere transport is mostly controlled by a large-scale meridional circulation, namely the Brewer-Dobson circulation. In this thesis, climatology and variability of the Brewer-Dobson circulation and the middle atmosphere has been analysed using the Canadian Middle Atmosphere Model (CMAM30-Ext). A number of key variables are used including the age of air, residual velocities, residual stream function, temperature and zonal wind. The analysis of the climatology of the age of air shows, in particular, that young air gets generated near the tropical tropopause, which then travels poleward. The residual stream function shows that the Brewer-Dobson circulation dominates the winter hemispheres around the solstices and becomes nearly symmetrical, with respect to the equator, around the equinoxes. The empirical orthogonal function analysis is applied to explore the modes of variability in the middle atmosphere. The analysis identifies, in particular, the semi-annual oscillation, the quasi-biennial oscillation with moderate explained variance compared to the variance explained by the annual cycle. In addition, the analysis also reveals the emergence of the solar cycle. Powered by TCPDF (www.tcpdf.org)
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Vertical variability of the 11 years solar cycle influence within the middle and higher atmosphere
Kuchař, Aleš ; Pišoft, Petr (advisor) ; Laštovička, Jan (referee)
This work investigates changes implied by variability of temperature, zonal wind and ozone mixing ratio during the eleven-year cycle in the stratosphere and lower mesosphere. The analysis is performed by using multiple linear regression of the MERRA reanalysis dataset for the period 1979-2012. Furthermore, we describe possibilities of available dataset, which can be also considered for the study of the upper atmosphere. Results of this study show a qualitative agreement with other related studies in the stratosphere, we find substantial differences especially in the ozone concentrations above the stratopause. It has been shown more intensive sudden stratospheric warming during solar maxima and the associated impact on the Brewer-Dobson circulation in all fields of meteorological variables.
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Climate-induced shifts of vegetation zones
Bareš, Jáchym ; Mikšovský, Jiří (advisor) ; Pišoft, Petr (referee)
This bachelor thesis examines changes in the extent of vegetation zones through- out the 1950-2020 time period in Europe. We utilise a climate classification based on two quantities: aridity index (AI) and growing degree-days (GDD). These quantities are commonly used for agricultural and gardening purposes as they represent two paramount characteristics for plant growth and survival: temperature and precipitation. The tem- perature and precipitation data was obtained from the E-OBS gridded dataset. On the basis of this data, we present maps of Europe that compare the extent of the classification zones in two periods: 1951-1980 and 1991-2020. It was found that GDD increased in almost all of the area under examination. AI decreased in the southern territories, but it increased in the northern ones. Furthermore, we apply the calculated GDD to study the shift of areas with satisfactory conditions for wheat in Scandinavia and observe their enlargement. 1
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Transport between the stratosphere and mesosphere
Zajíček, Radek ; Pišoft, Petr (advisor) ; Mikšovský, Jiří (referee)
The transport between the stratosphere and mesosphere is controlled by the large-scale Brewer- Dobson circulation. This thesis investigates the influence of greenhouse gases and ozone-depleting substances on the development of vertical flow in the middle atmosphere for the period 1960-2080, especially integrated flows through the stratopause. The vertical flow analysis is based on the residual stream function, the data of which were obtained by calculation from chemistry-climate models within the Chemistry-Climate Model Initiative (CCMI-1) . The results of the work show a clear effect of increasing concentration of greenhouse gases in the atmosphere on the amplification of the deep branch of the Brewer-Dobson circulation, both in ascending and descending movements.
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Coupling processes of various timescales in the middle atmosphere
Kuchař, Aleš ; Pišoft, Petr (advisor) ; Koucká Knížová, Petra (referee) ; Thiéblemont, Rémi (referee)
The thesis deals with the manifestation of coupling processes of various timescales in the middle atmosphere. Longer and shorter timescales are represented here by the 11-year solar cycle (SC) and orographic gravity waves (oGWs) considered on the intraseasonal timescale of the north hemisphere winter, respectively. The first two chapters deal with the application of rigorous attribution the variability of temperature, ozone and circulation characteristics in the stratosphere and lower mesosphere with regard to the SC using multiple nonlinear techniques (support vector regression and neural networks) besides the multiple linear regression approach. The aliasing of the SC with volcanic eruptions or the El Niňo Southern Oscillation is qualitatively assessed and its impact on conclusions about the top-down coupling mechanisms discussed. The last chapter examines the role of parametrized oGWs in the lower stratosphere. The Himalayan hotspot reveals common features with sudden stratospheric warmings such as the residual circulation amplification leading to a warming and ozone enrichment in the polar latitudes of the lower stratosphere.
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