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Wind data analysis
Hanslian, David ; Kalvová, Jaroslava (advisor) ; Huth, Radan (referee) ; Květoň, Vít (referee)
The doctoral thesis presents various methods of wind data analysis. Its first part summarizes the undesirable factors that influence the measured wind data. In particular, the effects of anemometer placement with regard to the near-by obstacles are investigated. In addition to the theoretical review, the practical examples of analysis of these effects at the wind mast measurements are demonstrated. The second part is focused on the measure-correlate-predict methods. Two original matrix-type methods are presented. Furthermore, a comparison of accuracy of measure-correlate-predict methods for various types of reference data series, various methods and various configurations of applied methods has been performed. The reanalyzed wind proved to be a suitable source of reference data in most cases. The applicability of surface wind data from meteorological stations depends on the combination of reference and target series, as well as on the homogeneity of involved data. The newly introduced methods proved to be suitable and universal tool for measure-correlate-predict application. The final part of the thesis analyses the wind conditions over the Czech Republic. Besides to the overview of the knowledge of the Czech wind climate, the calculation of the wind map of the Czech Republic is described. The final map was...
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Effect of global climate change on hydrological patterns in headwater catchments
Lamačová, Anna ; Hruška, Jakub (advisor) ; Tesař, Miroslav (referee) ; Kalvová, Jaroslava (referee)
The aims of this theses were (i) to evaluate trends in spring yields in the Czech Republic (period 1971-2007) and trends in runoff from small forested catchments of the GEOMON network during the period 1994-2011, (ii) evaluate the impact of climate change on streamwater chemistry in acid-sensitive catchment (Lysina), and (iii) estimate the impact of anticipated climate change projected according to different CO2 emission scenarios on flow patterns forested (GEOMON) and alpine headwater (Skalnaté Lake) catchments in the periods 2021-2050 and 2071-2100. Significant negative trends on the annual level were observed at 18% of springs while positive trends at only less than 0.5% of 157 tested objects and 4 of 18 regions revealed significant decreasing trend. To these regions belonged the zones of Carpathian Cretaceous and Paleogene sediments in the southeast and northeast of the Czech Republic, the zones of tertiary and Cretaceous basins in the southeast and Proterozoic and Paleozoic crystalline rocks in the central part of the Czech Republic. Most spring yields were decreasing within the summer months June- August (on average 24%) and least between February and April (on average 15%) (Paper I). There were no general patterns found indicating either significant increases or decreases in runoff on either...
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Assessment of regional climate models performance in simulating present-day climate over the area of the Czech Republic
Crhová, Lenka ; Kalvová, Jaroslava (advisor) ; Kliegrová, Stanislava (referee)
Title: Assessment of regional climate models performance in simulating present-day climate over the area of the Czech Republic Author: Lenka Crhová Department: Department of Meteorology and Environment Protection Supervisor:doc. RNDr. Jaroslava Kalvová, CSc. Supervisor's e-mail address: Jaroslava.Kalvova@mff.cuni.cz Abstract: Today a great attention is turned to climate changes and their impacts. Since eighties the Regional Climate Models (RCMs) are developed for assessment of future climate at regional scales. But their outputs suffer from many uncertain- ties. Therefore, it is necessary to assess models ability to simulate observed climate characteristics and uncertainties in their outputs before they are applied in consecu- tive studies. In the first chapters of this thesis the sources of uncertainties in climate model outputs and selected methods of climate models performance evaluation are reviewed. Several methods of model performance assessment are then applied to si- mulations of the Czech regional climate model ALADIN-Climate/CZ and selected RCMs from the ENSEMBLES project for the reference period 1961-1990 in the area of the Czech Republic. The attention is paid especially to comparison of simulated and observed spatial and temporal variability of several climatic elements. Within this thesis the...
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Uncertainties in regional climate models outputs
Holtanová, Eva ; Kalvová, Jaroslava (advisor) ; Halenka, Tomáš (referee) ; Dubrovský, Martin (referee)
Title: Uncertainties in regional climate models outputs Author: RNDr. Eva Holtanová Supervisor: doc. RNDr. Jaroslava Kalvová, CSc. Department: Dept. of Meteorology and Environment Protection Faculty of Mathematics and Physics Charles University in Prague Present doctoral thesis focuses on the analysis of uncertainties in regional climate model outputs in the area of the Czech Republic. Generally, the uncertainties in model outputs come from inaccuracies of initial and boundary conditions, further from the necessity to parameterize the small scale processes, and the structure of the model, e.g. the choice of numerical schemes or spatial resolution. In case of the simulations of future climate, another source of uncertainty arises. It is the unknown development of forcings that influence the climate system. The analysis in this work focuses on two multi-model ensembles, that come from two international European projects PRUDENCE and ENSEMBLES. The simulated 30-year mean seasonal air temperature and precipitation amounts are used, for the reference period 1961- 1990, and several future time periods. Two techniques were employed to assess the uncertainties. The first one was aimed at dividing the variance of a multi-model ensemble into contributions of regional model, driving global model and emission...
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The relationships between atmospheric circulation and surface climatic elements in Europe
Pokorná, Lucie ; Huth, Radan (advisor) ; Kalvová, Jaroslava (referee) ; Kliegrová, Stanislava (referee)
The relationships between atmospheric circulation and surface climatic elements in Europe Lucie Pokorná Abstract The variability of atmospheric circulation is the most important factor determining the changes in surface climatic elements. In this work, the relationship between atmospheric circulation and surface climatic elements like the temperature and the precipitation amounts and occurrence over the European region and some other climatic elements in central Europe is focused. The atmospheric circulation during the year is represented by modes of low-frequency circulation variability in sea level pressure (SLP) and 500-hPa heights (Z500) obtained by using statistical method "Principal component analysis". The Pearson correlation coefficient is used to describe the relationship between modes and climatic elements. Four circulation patterns in Z500 over Euro-Atlantic sector influence climate in Europe all over the year: the North Atlantic Oscillation (NAO) pattern, the East Atlantic (EA) pattern, and two Eurasian patterns (EU1, EU2). There were found patterns in SLP that strongly correlate with modes of the Z500 and influence surface climate similar way. Statistically important correlations of modes in Z500 and SLP with maximum, minimum and mean temperature, precipitation amounts and occurrence of...
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Uncertainty of regional climate models outputs
Kliková, Barbora ; Kalvová, Jaroslava (advisor) ; Pišoft, Petr (referee)
This thesis focuses on examination of the ability of regional climate models (RCMs) to simulate precipitation patterns in the Czech Republic and on evaluation of uncertainties due to different global climate models (GCMs) driving the same RCM and due to different RCMs driven by a single GCM. Model outputs of regional climate models RCAO and HIRHAM driven by global climate models HadAM3H and ECHAM for period 1961-1990 were analyzed. It was shown that spatial variability of mean annual precipitation totals is mainly influenced by RCM. The global driving model determines areal mean and minimum values of precipitation totals for the Czech Republic. Both regional models overestimate the mean annual precipitation totals over most of the area, more markedly with driving model ECHAM. After the analysis of the further precipitation characteristics in selected grid points, it was shown that models RCAO and HIRHAM simulate most of the characteristics differently. Most of the characteristics were not expressed well by the models; the results of the model RCAO were better. Further, the model results distinctively differ between chosen areas. This variability is more noticeable for HIRHAM.
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Analysis of daily minimum and maximum air temperature at Prague-Klementinum station
Tomšů, Radek ; Kalvová, Jaroslava (advisor) ; Mikšovský, Jiří (referee)
Long-term and continuous air temperature measurements at Prague-Klementinum (regular time observations are carried out since 1775, maximum and minimum air temperatures have been measured since 1881) are suitable for the analysis of possible climate changes. While researching the temperature extremes at this station, the increased occurrence of records of daily maximum air temperatures was documented in the second half of the 20th century, especially in the last 20 years, which is not connected to forcing Prague's urban heat island. There is a very rare occurrence of records of daily minimum air temperatures in the last 50 years, which is probably connected to forcing Prague's urban heat island, but also to the warming in the last decades. The change in the circulation is probably only a partial reason for high frequency of records of daily maximum air temperatures. There is warming about 1 řC by maximum air temperatures between periods 1961-83 a 1984-2006 in every season, except autumn. There is average warming about 0,5 řC by minimum air temperatures between periods 1961-83 a 1984-2006.
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Spatial variability of precipitation annual cycles
Zíková, Naděžda ; Kalvová, Jaroslava (advisor) ; Pišoft, Petr (referee)
This thesis enquires into the spatial variability of precipitation annual cycles and its representation by regional climate models. Goal is to find suitable metrics that could describe spatial character of the precipitation field and consequently evaluate model results. For complete understanding the issue, there is an introduction to modeling with regional climate models and also parameters of the precipitation in the Czech Republic. The main part of the thesis is an application of different methods of descripiton on the results of the regional climate models (including the Czech model ALADIN) and CRU data. Results of the models are compared to observed data transferred into the regular grid. Each method is applied on the model results and assessed with regard to advantages and disadvantages. The metrics that were found useful are recommended for the further evaluation of the spatial variability of precipitation annual cycles. The ALADIN model seems to be quite successfull, weak points are only modelling of the precipitation in spring and the effect of the continentality and oceanity on the precipitation annual cycles.
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