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The climate of Norway as a factor influencing tourism
Lhotka, Ondřej ; Sládek, Ivan (advisor) ; Míková, Taťána (referee)
This bachelor's work describes the elements of Norwegian climate, which have immediate influence on human activities in the nature. This work insist on the regime of sunshine in reference to the astronomical and meteorological factors. The duration of daylight and the presence of the polar day and the polar night is described for several places in Norway. The sunny and dark periods are defined for Oslo and Tromsø, the amount of cloud cover throught the year is illustrated, too. The temperature conditions are characterised throught the use of the map with mean annual temperature and the tables with mean month temperatures, mean month minimum temperatures and extreme temperatures. The wind regime is described in the table and illustrated throught the use of five wind roses. After it there is a map with mean annual precipitation and the tables with mean month precipitatation and the amount of precipitatation-days for several places. The height of the snow cover throught the year is described, too. At the end there is a suggestion about the content of "climatic guidebook" and a recommendation of proper time for visiting Norway.
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Extreme daily temperature range in Czechia in 1961-2007
Maňhal, Daniel ; Pokorná, Lucie (advisor) ; Lhotka, Ondřej (referee)
This thesis deals with the extreme daily temperature range (DTR) during the period 1961-2007 for the extended winter season, based on an analysis of the daily series from 49 climatological stations in the Czech Republic. The aim of the research was to find the frequency of the extreme DTR in the individual months and describe the effect of the sunshine, the snow cover and the altitude on the magnitude of the extreme DTR. Moreover, the work focused on the identification of typical synoptic situations, during the days with extreme DTR. During the study period, 1746 days with extreme DTR were detected at least at one climatological station. The extreme DTR occurred most often in March in the anticyclonic situations. During the days with strong wind, the eastern flow direction prevailed anticyclonic situations whereas the western direction prevailed cyclonic situations. The highest values of the extreme DTR generally occurred in the lowlands since the magnitude of extreme DTR decreased with increasing altitude. In general, the values of extreme DTR were reduced (by 0,2 řC on average) during the days with snow cover. Cloud cover had a similar effect, the mean difference of extreme DTR between cloudy days (defined as days with sunshine duration less than 1 h/day) and sunny days was 0,5 řC. The acquired...
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Long-term variability of heat waves and cold spells in Central Europe
Lhotka, Ondřej ; Kyselý, Jan (advisor) ; Halenka, Tomáš (referee) ; Huth, Radan (referee)
Title: Long-term variability of heat waves and cold spells in Central Europe Author: Mgr. Ondřej Lhotka Department: Department of Physical Geography and Geoecology, Faculty of Science, Charles University in Prague Supervisor: RNDr. Jan Kyselý, Ph.D., Institute of Atmospheric Physics, Czech Academy of Sciences Abstract: Heat waves and cold spells have serious impacts on natural environment and society. The main aims of this thesis are to examine past variability of Central European heat waves and cold spells, to assess severity of recent events in a long-term context, to evaluate simulation of heat waves in climate models, and to construct their scenarios for a possible future climate. Heat waves and cold spells were primarily investigated as spatial events, using gridded data sets. E-OBS gridded data was utilized to assess past variability of heat waves and cold spells and to evaluate regional climate model (RCM) simulations from the ENSEMBLES and EURO-CORDEX projects. An extremity index that captures joint effects of temperature, duration, and spatial extent of individual heat waves and cold spells was proposed and tested. The persistent 1994 heat wave was found to be the most extreme over Central Europe in the 1950−2012 period, and the summer of 2013 was unprecedented at several Central European stations...
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Duration of faling precipitations, fog and mist as factor influencing the timing of vacances
Kothan, Filip ; Sládek, Ivan (advisor) ; Lhotka, Ondřej (referee)
The aim of this paper is to determine suitable term of summer holidays. It should be as long as current holidays in Czech republic, it means 62 days. The paper builds on the bachelor's thesis titled "Optimal timing of summer vacances with regard to climate". The convenient term has been evaluated on basis of characteristics of air temperature, duration of sunshine and the length of day there in the bachelor's thesis. This paper contains the analysis of duration of rain, showers, drizzle, fog and mist. Thus, several terms have been found in both papers. But these are suitable with regard to only one meteorological element or phenomenon. The summer holidays should undoubtedly provide days with the best possible values of more meteorological elements. So the final term was calculated as mean and weighted mean of several dates of the beginning of holidays with the highest values of daily average air temperature, length of day and with the shortest total duration of the complex of rain, showers and drizzle and the complex of fog and mist. The weights of individual elements have been determined in two ways, so we have obtained three terms of holidays: two as result of the weighted mean and one as result of the mean. The best periods for holidays, determined by the weighted mean, are 11th June - 11th...
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Analysis of the temperature series of meteorological observatory Milešovka (1905 - 2010)
Lhotka, Ondřej ; Sládek, Ivan (advisor) ; Štekl, Josef (referee)
From the climatological aspect, the meteorological observatory Milešovka is one of the most important stations at Czech Republic. When this master's thesis was writen, the 106 years long set of the daily mean air temperature was available. This dataset is not influenced by the urban heat island. Beside the older studies, the trend of the mean annual air temperature increased on 1,02řC/100 years. The highest value is in the spring, the lowest one in the winter. The value of mean diurnal temperature range is increasing. The duration of the frost period is decreasing, on the contrary, the lenght of the growing season is prolonging. 36 % of the absolute extremes of maximal daily temperature were detected in the period 1996-2010. On the other hand, the absolute extremes of minimal daily temperature are rare in this period. The sub-seasonal anomalies are three or more days long significant deviations from the smoothed annual progress of the air temperature. This anomalies of the air temperature has highest mean value of deviations and longest mean duration in winter. The relations between the sub-seasonal anomalies and the meteorological singularities are weak.
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The climate of Norway as a factor influencing tourism
Lhotka, Ondřej ; Míková, Taťána (referee) ; Sládek, Ivan (advisor)
This bachelor's work describes the elements of Norwegian climate, which have immediate influence on human activities in the nature. This work insist on the regime of sunshine in reference to the astronomical and meteorological factors. The duration of daylight and the presence of the polar day and the polar night is described for several places in Norway. The sunny and dark periods are defined for Oslo and Tromsø, the amount of cloud cover throught the year is illustrated, too. The temperature conditions are characterised throught the use of the map with mean annual temperature and the tables with mean month temperatures, mean month minimum temperatures and extreme temperatures. The wind regime is described in the table and illustrated throught the use of five wind roses. After it there is a map with mean annual precipitation and the tables with mean month precipitatation and the amount of precipitatation-days for several places. The height of the snow cover throught the year is described, too. At the end there is a suggestion about the content of "climatic guidebook" and a recommendation of proper time for visiting Norway.
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Heat waves over Central Europe in ALADIN-Climate/CZ regional climate model: evaluation and future projections
Lhotka, Ondřej ; Farda, A. ; Kyselý, Jan
We evaluated a simulation of Central European heat waves and analysed possible changes of their characteristics in the future climate using the ALADIN-Climate/CZ regional climate model with 25km horizontal grid spacing. Lateral boundary conditions were provided by the ARPEGE global climate model, using historical forcing and the SRES A1B scenario. Observed data were taken from the E-OBS gridded data set. Heat waves were evaluated over 1970−1999 and changes in their characteristics were assessed for 2020−2049. Their definition is based on exceedance of the 90th percentile of summer daily maximum temperature calculated separately for modelled and observed data. ALADIN-Climate/CZ simulates characteristics for the recent climate quite well, especially the overall severity of heat waves. In contrast, temperature amplitude was considerably overestimated. This model projects an increase in overall heat wave severity by a factor of 2 to 3 in the future climate, primarily driven by an increasing number of events. The study shows that ALADIN-Climate/CZ is generally capable of simulating Central European heat waves, which gives more credibility to model projections of future heat waves.
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Analysis of temporal variability and spatial characteristics of heat waves in central Europe using extremity index
Lhotka, Ondřej ; Kyselý, Jan
Heat waves have severe consequences on natural environment and society. Th e majority of studies defined heat waves from station data only, so there is a need to examine these events not only from the aspect of point characteristics of air temperature and duration, but also from the view of their spatial extent. In this study, heat waves over Central Europe were analysed using the gridded E-OBS dataset. Th e extremity index of heat waves, which takes into account their spatial extent, duration, and peak temperature, was proposed and used to analyse variability of heat waves over Central Europe from 1950 to present. We delimited 220 hot days and 21 heat waves and computed the extremity index for each heat wave. Th e eight most signifi cant heat waves based on the extremity index were visualized. Temporal variability of hot days and heat waves was analysed and we demonstrate that the number of hot days and the severity of heat waves have been increasing.
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