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Nonstationarity of the effects of modes of atmospheric circulation variability on surface climate elements
Hynčica, Martin ; Huth, Radan (advisor) ; Dobrovolný, Petr (referee) ; Beck, Christoph (referee)
Circulation modes are highly correlated, yet often distant areas detected in a field of a circulation variable, such as sea level pressure, geopotential heights, wind speed, and wind components. They consist typically of two or more action centres, which simultaneously weaken or strengthen, hence affecting the intensity and direction of atmospheric circulation and consequently surface climatic elements, such as temperature and precipitation. Temporal variability of action centres affects spatiotemporal distribution of impact on surface climatic variables. The availability of gridded datasets allows investigation of temporal behaviour of action centres and its impact on surface climatic variables on long time scales over large regions, which is, therefore, the main scientific topic of this work. Due to a large amount of reanalyses differing in e.g. assimilated type of data and model used for their calculation, the comparison of representation of circulation modes and their temporal evolution of relationships with surface climatic elements is conducted between reanalyses. Circulation modes in reanalyses assimilating both surface and upper troposphere/satellite data (ERA40, JRA-55, NCEP-1) are mostly similar whereas the 20CRv2c reanalysis, which utilizes surface data only, contains biases. Although...
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Temporal stability of effects of the 11-year solar cycle on circulation conditions in central Europe
Paličková, Lea ; Huth, Radan (advisor) ; Halenka, Tomáš (referee)
Temporal stability of effects of the 11-year solar cycle on circulation conditions in central Europe Abstract The aim of this master thesis is to determinewhether circulation conditions in central Europe are affected by variable solar activity. Circulation type classification by Beck (2000) is used here to evaluate the solar effects. Circulation characteristics of circulation are available back to 1780. This master thesis proves that the solar cycle effects on circulation conditions in central Europe are not stationary in time. It was demonstrated that the frequency of individual circulation types varies significantly, depending on the length of studied period. The impact of solar variability on circulation conditions in central Europe is more significant when a shorter time period is being considered. It was also found that the response of circulation characteristics on solar variability is not immediate. There have not been clear results if there exists a linear trend on lagged response of solar variability on circulation characteristics. Linear trend has been found only for a whole year dataset with a lagged response within a year. This thesis proves that the solar cycle effects on troposphere are highly variable, so it is very difficult to define them straightforward. Keywords: atmospheric circulation,...
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The applicability of the Hess-Brezowsky synoptic classification to the description of climate elements in Europe
Sýkorová, Petra ; Huth, Radan (advisor) ; Racko, Stanislav (referee)
This thesis deals with the applicability of the Hess-Brezowsky synoptic classification to the description of climate elements, minimal and maximal temperatures and precipitation, in Europe. The first part of the thesis is an overview of the knowledge concerning circulation classifications (with emphasis on the Hess-Brezowsky synoptic classification) and its applicability to the description of climatic elements. In the second part of this thesis, the suitability of the Hess-Brezowsky classification for this purpose in the European domain is analyzed, using the two-sample Kolmogorov-Smirnov test. The test was performed on ECA&D data from 113 climatic stations for the years 1961 - 2000. The suitability of the classification for describing climatic elements at a given station was assessed according to the percentage of the synoptic types, during which the elements' probability distribution functions differed from the rest of the values. The classification was deemed most suitable for describing climatic elements in Germany and its neighboring states and least suitable in the Mediterranean and Eastern Europe. The classification was more suitable for the description of minimal and maximal temperatures than precipitation and less suitable for description of all climatic elements in the summer months than...
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Links between atmospheric circulation and surface air temperature distributions in climate models
Pejchová Plavcová, Eva ; Kyselý, Jan (advisor) ; Halenka, Tomáš (referee) ; Huth, Radan (referee)
Title: Links between atmospheric circulation and surface air temperature distributions in climate models Abstract: This thesis comprises a collection of five papers dealing with validation of regional climate model (RCM) simulations over Central Europe. The first paper illustrates and discusses problems with observed data that are used for model validation and how the choice of reference dataset affects the outcomes in validating the RCMs' performances. The second paper evaluates daily temperatures, and it indicates that some temperature biases may be related to deficiencies in the simulations of large- scale atmospheric circulation. RCMs' ability to simulate atmospheric circulation and the observed links between circulation and surface air temperatures are examined in detail in the third paper. This article also compares performances of individual RCMs with respect to the driving data by analysing the results for the driving data themselves. The fourth paper focuses on biases in the diurnal temperature range within RCMs and their possible causes by examining links of the errors to the at- mospheric circulation and cloud amount. The last paper investigates the observed relationships between atmospheric circulation and daily precipitation amounts over three regions in the Czech Republic, as well as how these...
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The application of atmospheric circulation classifications in the interpretation of climate model outputs
Stryhal, Jan ; Huth, Radan (advisor) ; Halenka, Tomáš (referee) ; Beranová, Romana (referee)
The application of atmospheric circulation classifications in the interpretation of climate model outputs Mgr. Jan Stryhal Automated (computer-assisted) classifications of atmospheric circulation patterns (circulation classifications, for short) constitute a tool widely used in synoptic and dynamic climatology to study atmospheric circulation and its link to various atmospheric, environmental, and societal phenomena. The application of circulation classifications to output of dynamical models of the atmosphere has developed considerably since the pioneering studies about three decades ago, reflecting rapid development in statistics, computing technology, and-naturally-climatological research, increasingly more and more dependent on simulations of the atmosphere, facing the paradigm of anthropogenic climate change. An uncoordinated use of various statistical approaches to analyzing output of global climate models (GCM) or their various ensembles, and an arbitrary selection of circulation variables, spatial and temporal domains, and reference datasets, have contributed to a need for a comparative study, which would shed some light on the sensitivity of studies dealing with an intercomparison of circulation classifications in two datasets to subjective choices. The present thesis responds to this need...
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The relationships between atmospheric circulation and surface climatic elements in Europe
Pokorná, Lucie ; Huth, Radan (advisor)
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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The application of atmospheric circulation classifications in the interpretation of climate model outputs
Stryhal, Jan ; Huth, Radan (advisor) ; Halenka, Tomáš (referee) ; Beranová, Romana (referee)
The application of atmospheric circulation classifications in the interpretation of climate model outputs Mgr. Jan Stryhal Automated (computer-assisted) classifications of atmospheric circulation patterns (circulation classifications, for short) constitute a tool widely used in synoptic and dynamic climatology to study atmospheric circulation and its link to various atmospheric, environmental, and societal phenomena. The application of circulation classifications to output of dynamical models of the atmosphere has developed considerably since the pioneering studies about three decades ago, reflecting rapid development in statistics, computing technology, and-naturally-climatological research, increasingly more and more dependent on simulations of the atmosphere, facing the paradigm of anthropogenic climate change. An uncoordinated use of various statistical approaches to analyzing output of global climate models (GCM) or their various ensembles, and an arbitrary selection of circulation variables, spatial and temporal domains, and reference datasets, have contributed to a need for a comparative study, which would shed some light on the sensitivity of studies dealing with an intercomparison of circulation classifications in two datasets to subjective choices. The present thesis responds to this need...
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Temporal stability of effects of the 11-year solar cycle on circulation conditions in central Europe
Paličková, Lea ; Huth, Radan (advisor) ; Halenka, Tomáš (referee)
Temporal stability of effects of the 11-year solar cycle on circulation conditions in central Europe Abstract The aim of this master thesis is to determinewhether circulation conditions in central Europe are affected by variable solar activity. Circulation type classification by Beck (2000) is used here to evaluate the solar effects. Circulation characteristics of circulation are available back to 1780. This master thesis proves that the solar cycle effects on circulation conditions in central Europe are not stationary in time. It was demonstrated that the frequency of individual circulation types varies significantly, depending on the length of studied period. The impact of solar variability on circulation conditions in central Europe is more significant when a shorter time period is being considered. It was also found that the response of circulation characteristics on solar variability is not immediate. There have not been clear results if there exists a linear trend on lagged response of solar variability on circulation characteristics. Linear trend has been found only for a whole year dataset with a lagged response within a year. This thesis proves that the solar cycle effects on troposphere are highly variable, so it is very difficult to define them straightforward. Keywords: atmospheric circulation,...
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The applicability of the Hess-Brezowsky synoptic classification to the description of climate elements in Europe
Sýkorová, Petra ; Huth, Radan (advisor) ; Racko, Stanislav (referee)
This thesis deals with the applicability of the Hess-Brezowsky synoptic classification to the description of climate elements, minimal and maximal temperatures and precipitation, in Europe. The first part of the thesis is an overview of the knowledge concerning circulation classifications (with emphasis on the Hess-Brezowsky synoptic classification) and its applicability to the description of climatic elements. In the second part of this thesis, the suitability of the Hess-Brezowsky classification for this purpose in the European domain is analyzed, using the two-sample Kolmogorov-Smirnov test. The test was performed on ECA&D data from 113 climatic stations for the years 1961 - 2000. The suitability of the classification for describing climatic elements at a given station was assessed according to the percentage of the synoptic types, during which the elements' probability distribution functions differed from the rest of the values. The classification was deemed most suitable for describing climatic elements in Germany and its neighboring states and least suitable in the Mediterranean and Eastern Europe. The classification was more suitable for the description of minimal and maximal temperatures than precipitation and less suitable for description of all climatic elements in the summer months than...
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Solar variability effects on characteristics of the Northern Hemisphere Circumpolar Vortex
Paličková, Lea ; Huth, Radan (advisor) ; Bochníček, Josef (referee)
This thesis contains an introduction to the problematics of solar activity variations in relation to tropospheric air circulation.It also contains thorough description of the influence of the solar activity on variable aspects of atmospheric circulation in the stratosphere and troposphere. The main target of this thesis is to determine, whether and how much is the Northern Hemisphere Circumpolar Vortex and its characteristics (surface, roundness, location of the centre) influenced by the level of solar activity. In the research part of this thesis, these characteristic values of the northern hemisphere circumpolar vortex from selected months in the years 1959-2001 are used. The thesis conributes to the international project COST ES1005 (Towards a more complete assessment of the impact of solar variability on the Earth's climate).
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