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Meteorological station system
Čada, Jan ; Balík, Miroslav (referee) ; Lattenberg, Ivo (advisor)
This bachelor thesis deals with the design and implementation of a online meteorological station system, which consists of individual weather stations that communicate via the Internet with the server. The first part of the thesis discusses the principles of measuring major meteorological variables and deals with the selection of suitable sensors for measuring temperature, atmospheric pressure, humidity, wind speed and rainfall. In the practical part, one of the weather stations based on Raspberry Pi Zero microcomputer is designed and realized. As a complement to the measured data, the station includes a camera that captures the view from the site where the meteostation is installed. 3D printing is used to realize most of the mechanical parts, it has the advantage of speed, accuracy and easy reproducibility. For the measurement of temperature, pressure and humidity, a combined sensor BME280 from Bosch is used, which is placed in a small Stevenson screen. The wind speed is measured by a cup anemometer whose rotation is sensed by an integrated Hall sensor. The output pulses are then counted using the PCF8583 circuit, which has an I2C interface for reading the values with a Raspberry Pi microcomputer. Special attention is paid to the construction of a custom calibratable tipping bucket rain gauge with a resolution of 0,5 mm, whose mechanical motion is also sensed by a Hall sensor as in the anemometer. The reading of the data from sensors and sending it to the server is handled by a Python script. For storing and presenting data to users, a custom server solution based on LAMP webserver is implemented, its source codes are written in PHP, HTML, JavaScript and CSS. In addition to the web interface, which displays the data in graphs, the measured data can be also presented to the user via an application for mobile devices based on Android. The application was developed in C# using the Xamarin framework in the Microsoft Visual Studio development environment. Among other things, it implements a widget for quick access to the measured values directly from the home screen. In the final part of the thesis, interesting findings obtained by observing the measured values are mentioned.
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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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Analysis of long-term changes of vegetation indices
Beránková, Petra ; Štych, Přemysl (advisor) ; Jedlička, Jan (referee)
The work deals with the issue of research of long-term changes of vegetation indices concretely indices NDVI (Normalized Difference Vegetation Index). The first part is devoted to detailed analysis of domestic and foreign literature, which deals with the calculation and interpretation of vegetation indices values. The main theme of this work is to explore relation between temperature and NDVI changes and precipitation and NDVI changes over the period 1982-2006. These connections are examined using correlation and regression analysis. Attention is concentrated to the Czech Republic, Central Europe and Finland. The average value of NDVI in Central Europe increased over the study period of 0,0012 per year. The average value of NDVI in Czech Republic increased of 0,0014 per year. On the territory of the Czech Republic increased the value of NDVI in three seasons (spring, autumn and winter). In the summer, in some areas, decreased NDVI values. Correlation coefficients between NDVI and temperature and NDVI and precipitation appeared consistently the highest in the spring. Keywords: NDVI, vegetation indices, temperature, precipitation, Central Europe, Czech Republic
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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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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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Signs and impacts of hydrological drought in the Rakovnicky stream basin
Maroušková, Kateřina ; Matoušková, Milada (advisor) ; Hrdinka, Tomáš (referee)
This thesis deals with the signs and impacts of the hydrological drought in the Rakovnicky stream basin. Its aim is to evaluate trends of the selected hydroclimatic variables, to analyze drought periods and land cover changes as one of the factors influencing a runoff regime in the catchment. The main methods used for the long-term and seasonal trends are Man-Kendall test, IHA analysis, flow duration curves and mass curves. Dry periods are evaluated based on Streamflow drought index (SDI), Low Flow index and runoff Q95 exeedance. Land use changes are analyzed using historical maps and index of change. Basic indices of ecological stability are calculated. According to the results the frequency and intensity of the hydrological drought in the Rakovnicky stream basin is increasing. Although the amount of a rainfall is consistent, its distribution throughout the year is changing. In addition the constantly increasing temperature and land use changes cause a significant runoff decreasing. To improve a water retention capacity in the cathment, it would be convenient to apply adaptation measures in the river channels and floodplains. Key words: rainfall, runoff, drought, ecological status, Rakovnicky stream
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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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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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