|
| |
|
|
Nonlinear modelling of meteorological data
Pop, Lukáš ; Raidl, Aleš (advisor) ; Mikšovský, Jiří (referee)
Thesis deals with possibilities of application of nonlinear methods based on the theory of dynamical systems, for meteorological problems. In the first part there is explored description of the dynamical systems, namely deterministic chaotic systems, for them this methods were introduced. There is described the concept of attractor and its typical invariants. In the next part there are summarized different ways of reconstruction of phase space of system by means of time series produced by it. A modification of Cao's method is proposed here. Possibilities of prediction of meteorological quantities are proposed here. In the next part there is described influence of different sorts of signal noise and inaccuracies of measuring to the dynamical system that is described by logistic equation. That is a simple example of deterministic chaotic system. In the last part there are analysed single types of errors, of them nonlinear methods of prediction are encumbered. There are described typical properties and specialities of meteorological data. There are tried modifications of local linear models also, what is applied to data of NCEP/NCAR reanalysis.
|
|
| |
|
| |
|
|
Determination of wind direction and speed from free atmosphere data
Mach, Václav ; Huth, Radan (advisor) ; Mikšovský, Jiří (referee)
4 Abstract Determination of wind direction and speed from free atmosphere data. This work deals with relationship between surface wind and large-scale predictors in the Czech Republic. Approach is statistical downscaling based on multiple linear regression with stepwise screening. Tested predictors include four geopotential heights (hgt 500, hgt 700, hgt 850 and hgt 1000), sea level pressure and surface wind components U and V. Observed surface wind speed and azimuth from 18 meteorological station ČHMÚ is used as predictand. Period of interest is define by used data on term 1961 - 2010. In three different methods are compared straight downscaling of wind components U and V, used wind speed calculate from downscaled components U and V, and straight downscaling of wind speed without distinguish wind direction. Resulting models are tested by cross-validation method. The resulting equation allows good simulation of surface wind at most of station. The better method to downscaling surface wind speed is prescribe method of calculate wind speed from downscaled components U and V.
|
|
|
Climate-induced shifts of vegetation zones
Bareš, Jáchym ; Mikšovský, Jiří (advisor) ; Pišoft, Petr (referee)
This bachelor thesis examines changes in the extent of vegetation zones through- out the 1950-2020 time period in Europe. We utilise a climate classification based on two quantities: aridity index (AI) and growing degree-days (GDD). These quantities are commonly used for agricultural and gardening purposes as they represent two paramount characteristics for plant growth and survival: temperature and precipitation. The tem- perature and precipitation data was obtained from the E-OBS gridded dataset. On the basis of this data, we present maps of Europe that compare the extent of the classification zones in two periods: 1951-1980 and 1991-2020. It was found that GDD increased in almost all of the area under examination. AI decreased in the southern territories, but it increased in the northern ones. Furthermore, we apply the calculated GDD to study the shift of areas with satisfactory conditions for wheat in Scandinavia and observe their enlargement. 1
|
|
|
Transport between the stratosphere and mesosphere
Zajíček, Radek ; Pišoft, Petr (advisor) ; Mikšovský, Jiří (referee)
The transport between the stratosphere and mesosphere is controlled by the large-scale Brewer- Dobson circulation. This thesis investigates the influence of greenhouse gases and ozone-depleting substances on the development of vertical flow in the middle atmosphere for the period 1960-2080, especially integrated flows through the stratopause. The vertical flow analysis is based on the residual stream function, the data of which were obtained by calculation from chemistry-climate models within the Chemistry-Climate Model Initiative (CCMI-1) . The results of the work show a clear effect of increasing concentration of greenhouse gases in the atmosphere on the amplification of the deep branch of the Brewer-Dobson circulation, both in ascending and descending movements.
|
|
|
High resolution spectroscopy of exoplanets - tool for characterization
Dupkala, Daniel ; Kabáth, Petr (advisor) ; Mikšovský, Jiří (referee)
We observed 211 spectra of transiting exoplanet MASCARA-2b (also known as KELT-20b) with OES echelle spectrograph installed at Perek telescope at Astronomical Institute of Czech Academy of Sciences. All data were acquired in 2018. From the total number of observed frames 100 were acquired during transit phase. Spectroscopic time series taken during transit can reveal characteristics of the exoplanet itself. In this work we will present data reduction of the echelle spectroscopy along with analysis of the reduced data. We discuss suitability of the data from Perek telescope for further characterization of exoplanetary systems. We will present the detection limits in this work. Expected aim is to understand the systematic errors and the data sets from Perek telescope in general and their suitability for spectroscopic follow-up in the era of bright TESS exoplanet host stars. 1
|
|
|
Interdiurnal variability of air temperature
Vodičková, Kateřina ; Holtanová, Eva (advisor) ; Mikšovský, Jiří (referee)
Title: Interdiurnal variability of air temperature Author: Kateřina Vodičková Department: Department of Atmospheric Physics Supervisor: RNDr. Eva Holtanová, Ph.D., Department of Atmospheric Physics Abstract: One of important climate characteristics is interdiurnal variability of air temperature. Significant attention of the bachelor thesis was paid to anomalies from a smoothed annual course of daily mean air temperature and their interdiurnal and multidiurnal variability. Changes of anomalies and their variability during period 1900-2015 on various climatologic stations in central Europe were studied. The changes of anomalies and their interdiurnal variability fits the changes of the air temperature in the 20th century. An increasing trend of interdiurnal variability of anomalies of air temperature in last decades was found. Keywords: air temperature, variability, interdiurnal changes, mean annual cycle, anomaly from mean annual cycle
|
|
| |
guest ::
RSS feed.