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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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Normality Testing of some Elements of Climate
Jelínek, Petr ; Huth, Radan (advisor) ; Antoch, Jaromír (referee)
Normality of daily temperature is often presumed in climatology. This study aims to verify the adequacy of such a model and possibly design a better one. A set of 20th century temperature data from all parts of Europe is examined. An effort is made to find out, whether regional differences in temperature distribution exist. Chapter 2 describes the preliminary trasformation of the data. In Chapter 3, several normality tests are conducted, based on both higher order statistical moments and EDF goodness-of-fit. Chapter 4 introduces finite normal mixtures, Engelman-Hartigan test and an iterative EM algorithm are applied. Chapter 5 summarizes the results.
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The Processing of Climatologic Records from Experimental Locations in Kyrgyzstan and the Synoptic-climatologic Interpretation Thereof
Sýkorová, Petra ; Huth, Radan (advisor) ; Pokorná, Lucie (referee)
The Charles University Faculty of Science KFGG team took part in an intensive research in the area of Kyrgyz glacial lakes. The collecting of records from three meteorological stations in the locations of Kolor (2,700 m above sea level) and Adygine (3,500 and 3,800 meters above sea level) was part of the research. The aim of this thesis was to analyze the homogeneity of climatic data measured in experimental locations using the SNHT method (Standard Normal Homogeneity Test), process the data using general climatological processes, create a classification of circulation types for the area of interest using Jenkinson's and Collinson's method, and finally, to quantify the relationships between individual circulation types and the values of chosen climatic elements. The analysis results are homogenized climatic sets for the Adygine H station (3,800 m above sea level) and a summary of basic statistics and trends of climatic elements in the area. Furthermore, a catalogue of circulation types was created for the period from August 2007 to July 2011, and finally, the relationships between individual circulation types and manifestations of climate elements (air temperature, precipitation and global radiation). The results of this thesis may be used to identify the types connected with bursts of glacial...
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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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Effects of temperature extremes on hospital admissions for cardiovascular diseases
Urban, Aleš ; Kyselý, Jan (advisor) ; Huth, Radan (referee)
Faculty of Sicence, Charles University Aleš Urban, Praha 2012 Effects of temperature extremes on hospital admissions for cardiovascular diseases The thesis compares differences in the impacts of warm and cold days on both excess mortality and hospitalizations for individual cardiovascular diseases (CVDs) in Prague and a selected rural region (southern Bohemia - JČ) consisting of the Jihočeský kraj and Vysočina districts in the period 1994- 2009. Population size and age structure are similar in the two regions. The differences are compared between selected population groups (men and women; < 65 and 65+ years). Value of the 90% (10%) percentile of daily mean air temperature in summer (winter) during the period were used for the definition of warm (cold) days for each region separately. The excess mortality and hospitalizations were determined as the difference from standardized daily counts of death and hospital admissions, adjusted for the epidemics of influenza/acute respiratory infections, and for annual and weekly cycles of mortality and hospitalizations. In Prague on warm days, we observed a significant (p = 0.05) excess mortality for CVD as a whole as well as for individual diagnoses, in more population groups than in the JČ region. The highest relative excess mortality on warm days in Prague was...
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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.
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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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Arctic sea ice variations from the point of view of the global climate change
Škopan, Viktor ; Huth, Radan (advisor) ; Šobr, Miroslav (referee)
The Arctic is one of the regions of the Earth most vulnerable to climate change. Temperatures in the Arctic have risen by more than twice the global average over the past few decades and are roughly 4 řC above the temperature at the start of the Industrial Revolution, which occurred in the late 18th century. It is highly likely that anthropogenic activity is responsible for such a dramatic change. The Arctic sea ice responds to these changes by decreasing in area, thickness, age and other parameters. The most significant decline has been recorded in the summer months, when the area of the sea ice is shrinking at an average rate of 12.8 % per decade. There has also been a significant decline in the age of sea ice. Forty years ago, sea ice older than four years accounted for 30 % of the total area covered by sea ice, whereas today such old ice accounts for only 2 %. Positive climate feedbacks are contributing significantly to the rapid warming of the Arctic and increased sea ice melt. An example is the decreasing albedo (reflectivity) of the Arctic Ocean, which reflects much less solar radiation due to the shrinking sea ice, contributing to the faster warming of the region and higher sea ice melt. Models show that the warming of the Arctic will continue in the future, and temperatures in the Arctic...
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