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Sea surface temperature variability in the North Atlantic and its effect on temperature and precipitation in Europe
Kodetová, Tereza ; Pokorná, Lucie (advisor) ; Beranová, Romana (referee)
The sea surface temperature (SST) of the North Atlantic (NA) has a demonstrable impact on Europe's climate. The main purpose of this final thesis is to investigate the long-term evolution of SST in SA and to describe the influence of SST change in NA on temperatures and precipitation in Europe. For this purpose, the freely available HadISST database from the Met Office Hadley Centre Observations datasets was chosen. The study period 1980-2019 was chosen so that the data would not be affected by switching to a different measurement type or processing method, and also by the inclusion of satellite measurements. This means that the data was acquired after the start of satellite measurements, which provides a much higher quality and more comprehensive coverage of the area. The next step was to calculate the average monthly and annual SSTs in the NA area of interest. Monthly mean SSTs ranged from 2,3 řC in the coldest month of March to the highest measured mean SST of 18,5 řC in August. The average annual SST of the area of interest was 10,5 řC over the 40 years analysed. Next, monthly and annual trends were detected from 1980-2019. The trends range from -0,7 řC to 1,5 řC, but it was confirmed that the area of interest is warming in all months over the 40 year period. The final objective was to...
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Automated area measurement of precipitation intensity via a network of microwave links
Bubniak, Milan ; Pospíšil, Ondřej (referee) ; Musil, Petr (advisor)
Point-to-point microwave links can be utilized as a large sensor network to measure rainfall. This work deals with the application of this procedure in practice. The first part of the thesis deals with atmospheric precipitation in general and standard methods of their measurement; and the propagation of the microwave signal and various causes of its attenuation, focusing on the attenuation caused by rain and the recommendation ITU-R P.838. This is followed by a state of the art summarization of the measurement of rainfall by microwave links. In the second part of the work, a manual procedure for calculating rainfall from microwave link data is performed, taking wet antenna attenuation into account. Then the creation of a support tool in the C# language is being described, which supply the data to the functions of the RAINLINK rainfall calculation library. Several rainfall calculations that are validated by physical rain gauges are performed. Furthermore, the own Telcorain application for rainfall calculation is created in the Python language, based on the pycomlink library. It has a graphical user interface created in PyQt. Several rainfall calculations validated by rain gauges are performed again, and the results are compared with the RAINLINK library.
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Moisture fluxes and precipitation in Europe
Lemarie, Petr ; Müller, Miloslav (advisor) ; Šmídová, Jana (referee)
The present thesis deals with the influnence of moisture flux and variables, it is derived from, on rainfall in Europe. Sources of this thesis are the NCAR/NCEP and the ERA-40 reanalysis and the GPCC and the ECA&D rainfall databases. A western moisture flux prevails on studied 850 hPa isobaric level, it reaches the highest intensities over the Atlantic around 55th parallel of latitude. There is the highest correlation between moisture flux magnitude and monthly rainfall in winter on the western coast of Europe and it decreases in summer and eastwards. The correlation is very weak or none in some parts of Europe, especially in the eastern Mediterranean. Extremely wet months are related with different intensive moisture flux directions in different parts of Europe, for example there is the highest correlation of monthly rainfall with the northern moisture flux in the Czech Republic. Several selected heavy precipitation episodes in Europe are presented in this thesis - during them the moisture flux anomaly is observed, but it differs in orientation and intensity. A high wind speed causes this anomaly more frequently than a humidity. This does not apply to every event, furher research is needed to draw general patterns of moisture flux during high precipitation events.
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Effect of molybdenum content on phase transformations in binary Ti-Mo alloys
Valešová, Veronika ; Stráský, Josef (advisor) ; Janeček, Miloš (referee)
Title: Effect of molybdenum content on phase transformations in binary Ti-Mo alloys Author: Veronika Valešová Department: Department of Physics of Materials Supervisor: PhDr. RNDr. Josef Stráský, Ph.D., Department of Physics of Mate- rials Abstract: β titanium alloys are highly appreciated group of structural materials. They provide an extraordinary combination of strength, toughness and fatigue resistance. These alloys are used predominantly in aerospace sector, chemical industry and medical engineering. We have studied three binary titanium alloys: Ti-12Mo, Ti-15Mo and Ti-18Mo (wt %). Apart from low temperature hexagonal close packed α phase and high temperature base centered cubic β phase, a metastable ω phase can be also found in this type of alloys. The ω phase is created in a diffusionless process by shifting the planes in the β phase and affects both mechanical properties and the α phase precipitation. We have examined the phase transformations occurring in the studied alloys using both in-situ and ex-situ methods. Resistometry, dilatometry and differential scanning calorimetry were used as the indirect in-situ methods. For the ex-situ methods, scanning electron microscopy and microhardness measurement were used. Complex characterization of β metastable titanium alloys showed the formation of the...
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Variability of water quality parameters in selected reservoirs in Prague
Stará, Eva ; Ettler, Vojtěch (advisor) ; Chalupová, Dagmar (referee)
Small water reservoirs in urban areas have important landscape-forming and environmental roles. However, numerous anthropogenic activities can influence the water quality in these urban ponds. This thesis evaluates and compares the water quality in selected ponds in Prague area (Motol, Stodůlky, Háje) by means of regular water monitoring between May and November 2013. Parameters commonly used as indicators of anthropogenic load were monitored (NO3 - , NH4 + , PO4 3- , Cl- , dissolved oxygen, chemical oxygen demand) and supplemented with the investigation of other chemical and physico-chemical parameters (alkalinity, acidity, water hardness, pH, Ca2+ , NO2 - , specific conductivity). Data were evaluated using Czech technical norm (ČSN - EN 75 7221), which defines five categories of surface water quality. Our data indicated that surface water from reservoirs in Motol exhibited the best water quality (1st category), reservoirs from Stodůlky were slightly polluted and reservoirs from Háje exhibited the poorest water quality (with some parameters exhibiting values corresponding to the 4th category). We found statistically significant correlations between the alkalinity, water hardness, COD and concentrations of NO3 - , Ca2+ , Cl- and PO4 3- . Moreover, numerous parameters are dependent on cumulative...
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Runoff Changes in the Šumava/Bohemian Forest Region
Fiala, Ondřej ; Kliment, Zdeněk (advisor) ; Královec, Václav (referee)
RUNOFF CHANGES IN THE ŠUMAVA / BOHEMIAN FOREST REGION Abstract: The goal of this thesis is to the evaluation of possible causes of changes in runoff regime in the Šumava region from time and spacial point of view. The thesis includes research and applied part. The research part is dedicated to methods of evaluation of runoff changes and their possible causes in teh Šumava region such as anthropogenic factors (changes in the river network, dams, drainage, land - use changes), natural factors (climate changes, peatbogs influence) and disturbances (wind calamities and bark beetle outbreaks, floods). In the applied part there is an analysis of precipitaion - runoff regime for long-term time series of average annual, monthly and minimal daily discharges and monthly precipitations for selected gauging stations in upper Otava, Ostružná, Volyňka, upper Blanice and Teplá Vltava basins using simple and double mass curves and Mann - Kendall test. In conclusion the achieved results were evaluated, discussed and compared with subject publications. Key words: disturbance, Mann - Kendall test, runoff, discharge, mass curves, precipitation, Šumava, changes
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Influence of Climatic Factor for Landslides Formation
Olejár, Filip ; Novotný, Jan (advisor) ; Kudrna, Zdeněk (referee)
TITLE INFLUENCE OF CLIMATIC FACTOR FOR LANDSLIDES FORMATION ABSTRACT Slope movements are divided into several groups, either by speed, method of movement or by factors causing their formation. The climate conditions of different territories are one of the main reasons that significantly affect the formation of slope movements. The most important climate factor that causes slope movements is precipitation. However, the effect of freezing soil can also be included here because water in the soil changes its volume and after thawing changing geomechanical properties of the material. In this work, the impact of precipitation will be discussed as the most significant climatic factor that induces breaking of the slopes. Rainwater can either gradually infiltrate into the slope, or can infiltrate in the single event with a high amount of rainfall, until it reaches a critical stage during which the weight of watered zone together with pore pressure are being increased whereas the effective shear strength is being reduced. This causes subsequent disintegration of the slope and movement of material along the slip surface in case of sliding movements and along the native surface in case of debris flows. This work summarizes the available knowledge about the precipitation as a significant factor which affects the...
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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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Effects of the El Niño / Southern Oscillation on the climate of New Zealand
Brambus, Ondřej ; Huth, Radan (advisor) ; Müller, Miloslav (referee)
The climatic phenomena El Nino, Southern Oscillation (SO), their interaction (ENSO) and effects of ENSO on the climate of New Zealand is investigated in this bachelor's thesis. The thesis is divided into three parts. The first one (chapter 3) explains the terminology, general connections and conditions favorable for origination of an ENSO event. The second part (chapter 4) summarizes the main research related to ENSO effects on the climate of New Zealand. In this part not only meteorological and climatological studies are mentioned, but also hydrological or dendrochronological studies. The last part (chapter 5) is based on my research which examines influences in SOI (Southern Oscillation Index) changes to temperature and precipitation variables in New Zealand. During El Nino events the yearly temperature amplitude in Northern part of North Island of New Zealand tends to be bigger than the amplitude during La Nina events. This conclusion is based on correlation analysis between SOI and temperature datasets. Impact of SOI changes on precipitation variability was not confirmed.
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