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Climatology of mediterranean cyclones
Suchan, Petr ; Žák, Michal (advisor) ; Metelka, Ladislav (referee)
This work deals with climatology of mediterranean cyclones. In first chapter short description of the Mediterranean area is given, second chapter depicts climate properties of Mediterranean focussed on air temperature, sea surface temperature and precipitations. Third chapter characterises Mediterranean cyclones, briefly brings some facts about their dividing and possibilities of their cyclogenesis in the Mediterranean area. In the last chapter the influence of cyclones at least partly originating in Mediterranean on the weather in the Czech Republic is studied.
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Relationship between the UV index and selected parameters
Tomanová, Helena ; Pokorná, Lucie (advisor) ; Metelka, Ladislav (referee)
Relationship between the UV index and selected parameters Abstract Ultraviolet radiation (UV radiation) is a shortwave radiation with wavelengths from 100 to 400 nm. This radiation has both positive and negative effects on living organisms and human health. Therefor the so-called UV index (UVI), characterizing the biological effect of UV radiation on human health was defined in 1994. This thesis aims to evaluate the link between selected factors (total ozone column, solar elevation angel, cloudiness and altitude) and the UVI values. Observed data at four stations in Czechia (Hradec Králové, Košetice, Kuchařovice, Labská bouda) and SYNOP reports from the four nearest stations during the period 2010−2017 were used. The Sun elevation (angle of Sun ray) has the strongest effect on the UVI values. The highest UVI values are generally reached at high angels when the Sun rays go the shortest path through the atmosphere. The increase of the UVI is exponential, from an angle of 30ř the increase is approximately linear. The UVI values increase on average by 0.8 at the Hradec Králové station and by 0.9 at the Labská bouda station for angle increasing by 5ř. The effect of clouds is significant and depends on the height and the clouds amount. High level clouds reduce UVI negligible, overcast sky by only 15 %. Medium and...
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Spatiotemporal variability of global and regional climate models
Crhová, Lenka ; Holtanová, Eva (advisor) ; Huth, Radan (referee) ; Metelka, Ladislav (referee)
Title: Spatiotemporal variability of global and regional climate models Author: RNDr. Lenka Crhová Department: Department of Atmospheric Physics Supervisor: RNDr. Eva Holtanová, Ph.D., Department of Atmospheric Physics Abstract: This thesis deals with variability of basic meteorological variables in global and regional climate models (GCMs and RCMs) outputs. Three different approaches were used in order to analyse climate models' ability to represent different aspects of variability of meteorological variables. The temporal variability with focus on its changes during a time and temporal scale components were studied. The relationship between air temperature and precipitation were employed in order to investigate the representation of spatiotemporal variability in climate models. Moreover, the influence of different characteristics of climate model simulations, such as the size of the RCM integration domain or differences between RCM and GCM simulations, were also considered. Two simulations of RCM ALADIN-Climate/CZ with different sizes of integration domain and their driving simulation of GCM ARPÉGE-Climat were used for analysis of the temporal changes in temperature mean and variability and selected simulations of RCMs and GCMs from the EURO-CORDEX and CMIP5 projects were employed for analyses of...
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Global changes in the midlatitude stratosphere
Kozubek, Michal ; Laštovička, Jan (advisor) ; Halenka, Tomáš (referee) ; Metelka, Ladislav (referee)
Several phenomena in the middle latitude stratosphere are studied in the thesis. The reanalyses are utilized as a source of data for our study. Different reanalyses are compared each other and with observations and problems of reanalyses are shown. We are interested in connection between ozone, dynamics and other phenomena (Sudden Stratospheric Warmings, solar cycle, NAO etc.) in the stratosphere, mainly from 1979 to present using ERA-Interim, NCEP/NCAR reanalyses or satellite observations. The linear connection between total ozone difference and 100 hPa eddy heat flux is found in winter middle latitudes. Ozone trends in Europe and China are analysed. The meridional and zonal wind is also studied using MERRA reanalysis and model output (CCM SOCOL v3.0). The comparison of geographical distribution of geopotential height and meridional wind is done. Differences between MERRA and CCM SOCOL v3.0 has been observed for geopotential hight and meridional wind for winter season.
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Climatology of mediterranean cyclones
Suchan, Petr ; Žák, Michal (advisor) ; Metelka, Ladislav (referee)
This work deals with climatology of mediterranean cyclones. In first chapter short description of the Mediterranean area is given, second chapter depicts climate properties of Mediterranean focussed on air temperature, sea surface temperature and precipitations. Third chapter characterises Mediterranean cyclones, briefly brings some facts about their dividing and possibilities of their cyclogenesis in the Mediterranean area. In the last chapter the influence of cyclones at least partly originating in Mediterranean on the weather in the Czech Republic is studied.
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Regional Climate Modeling
Belda, Michal ; Halenka, Tomáš (advisor) ; Huth, Radan (referee) ; Metelka, Ladislav (referee)
Regional climate models are commonly used for downscaling global climate simulations to the regional scale using nested limited-area models. One of the main goals of this work was the application of regional model RegCM in very high resolution for the region with complex topography in the framework of EC FP6 project CECILIA. RegCM was employed to downscale climate change scenario simulations performed by ECHAM5 model according to the IPCC A1B emission scenario for Central and Eastern Europe in 10km resolution. Validation of model performance, assessed by nesting RegCM in ERA-40 reanalysis, shows improvement of regional climate patterns mainly in mountainous areas. Temperature is well represented with mostly cold bias around -1 žC. Precipitation is affected by large biases around 80 %, in mountainous areas up to 400 % overestimation in winter. Downscaled climate change signal shows average warming 0.51.5 žC in period 20212050 and 24 žC in period 20712100. Precipitation changes are mostly within ±0.5 mm/day. RegCM3beta version with adjusted precipitation scheme parameters shows improvement of the precipitation bias, difference in climate change is rather negligible. Experiments with different convection schemes of RegCM in a case study for Africa performed in the framework of CORDEX project are...
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The influence of long-term changes of atmospheric circulation on observed trends of surface climatic elements in the Czech Republic and Europe
Cahynová, Monika ; Huth, Radan (advisor) ; Metelka, Ladislav (referee) ; Halenka, Tomáš (referee)
(English) RNDr. Monika Cahynová: The influence of long-term changes of atmospheric circulation on observed trends of surface climatic elements in the Czech Republic and Europe The aim of this thesis is to quantify the links between recent atmospheric circulation changes over Europe and local surface climatic trends. We employ several parallel classifications of circulation types that were collected and developed within the COST733 Action "Harmonisation and Applications of Weather Types Classifications for European Regions". To our knowledge, such a comparative approach has not been used so far. Atmospheric circulation changes over Europe were studied in terms of changing seasonal frequency and persistence of daily circulation types in the second half of the 20th century. The extensive collection of both subjective and objective catalogues of circulation types in European regions from the COST733 Action served as a platform for comparison of different classification methods, varying numbers of circulation types, and spatial scale of circulation processes. The most prominent trend - winter increase in the number of days with westerly flow - clearly stems from the strengthening of the North Atlantic Oscillation. The objective classifications did not show any systematic change of persistence of...
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Long term variability of the relationshops between atmospheric circulation and surface climate elemets
Beranová, Romana ; Huth, Radan (advisor) ; Halenka, Tomáš (referee) ; Metelka, Ladislav (referee)
The stability of the relationships between atmospheric circulation and the surface climatic variables is an important precondition to construct scenarios of climate change by statistical methods. The aim of the work is therefore to examine if and how the relationships between atmospheric circulation (characterized by geopotenial heights of 500 hPa level) and surface climatic elements (mainly temperature and precipitation) are changing in European region and in the Czech Republic. The relationship between the NAO index and both temperature and precipitation were analysed for long period (1901-99) at 29 resp. 27 European stations. The NAO index strong influences climate in Europe. However, the relationships were changing in time. The course of 31-years running correlation differs between different European regions and different seasons. The circulation modes were identified in geopotential heights of 500 hPa level by rotated principal component analysis for period 1958-98. The climate in Europe is influenced by NAO, EA, EU1, EU2 and NA mode. The variability of the relationships was represented by 15-year running correlations at more than 100 European stations. The regions with similar courses of running correlations were identified by cluster analysis (PAM method). Despite the considerable variability of the...
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Changes of length of periods with characteristic temperatures
Černochová, Eva ; Metelka, Ladislav (referee) ; Kalvová, Jaroslava (advisor)
Title: Changes of lengths of periods with characteristic air temperatures Author: Eva Černochová Department: Department of Meteorology and Environment Protection Supervisor: doc. RNDr. Jaroslava Kalvová, CSc. Supervisor's e-mail address: jaroslava.kalvova@mff.cuni.cz Abstract: Lengths of periods with characteristic air temperatures were derived using two different methods (linear interpolation, robust locally weighted regression) for 10 stations in the Czech Republic and for output data of regional climate models HIRHAM and RCAO in 4 grid points. Averages for a forty-year period (1961-2000) and for a thirty-year period (1961-1990) were computed as well as averages for every decade. Considerable attention was also paid to the analysis of methods used in the research. Most stations showed lengthening of growing season and summer during the twentieth century. Decennary average length of growing season and summer shortened in the years 1971-1980. The comparison of output data of regional climate models HIRHAM and RCAO and measured station data showed that the thirty-year average lengths of growing season and summer estimated by the two models were reasonably accurate approximately half of all cases. The models' estimates were not accurate at all concerning decennary averages. Keywords: robust locally...
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