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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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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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Changes in occurrence of climate types in the simulations of future climate
Mejsnar, Jan ; Mikšovský, Jiří (advisor) ; Halenka, Tomáš (referee)
The thesis compares climate classification of the Czech Republic based on two regional climate models (ALADIN-Climate and RegCM3) and on two model period (1961-1990 and 2021-2050). First, a short summary of climate classifications suitable for the Czech Republic is introduced. Above all are mentioned the classifications of Köppen, Kurpelová and Konček. The advantages of these classification are presented, especially their relation to occurrence of vegetation. Further, this thesis mentions today's regional climate models. The data of monthly values of precipitation and temperature were analysed by single classifications criteria and consequently visualized by the program SURFER to show individual climatic subtypes. The data represented averaged values for the periods 1961-1990 and 2021-2050. Finally the distribution and the veracity of both models are discussed.
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