|
|
On the assessment of urbanization application in weather forecasting model
Nováková, Tereza ; Halenka, Tomáš (advisor) ; Žák, Michal (referee)
Built-up areas represent an artifiial impait to natural environment with large spatial variability and speiifi meihaniit radiationt thermal and ihemiial properties. Despite of inireasing horizontal resolution of numeriial weather prediition modelst the impait of loial built-up area on mesosynoptiv weather phenomena is still not well resolved. Therefore it is neiessary to use some of urban environment modelst whiih were designed to parameterize speiifi urban prosiessest not expliiitly resolved inside the grid box. In the thesis main urban iharaiteristiis are explained (impait on the struiture of boundary layert radiation and heat balanie of urban environment or urban heat island)t basii priniiples of urbanization appliiation in the numeriial weather model are desiribedt as well as different urban parameterizations available in numeriial model WRFe (Weather Reseaih and Feoreiasting). Number of validation experiments were performed for summer and winter episode in non-hydrostatii mode at 3t3 km resolutiont where different urban parametrizationst antropogenii heat adjustment and impait of mosaii land-use were tested. April 2018 Prague weather foreiast was verifiated in ionsideration of urban heat island.
|
|
|
Turbulence modeling with WRF model
Peštová, Zuzana ; Belda, Michal (advisor) ; Halenka, Tomáš (referee)
This bachelor's thesis deals with the comparison of WRF simulation results using the Large Eddy Simulation (LES) and physical parametrization at lower resolution. The first part is dedicated to the turbulent flow and Navier-Stokes equations. This part also contains basic information on the methods by which we can model the turbulent flow. These methods are DNS, RANS and LES. In the next part, atmospheric numerical models are presented and the WRF model is described in more detail, including a description of its execution. The main part of the thesis deals with the description of the performed simulations and the comparison of the results. The results obtained are compared first with real data and then for individual simulations with different parameterizations. 1
|
|
|
Tests and validation of WRF model for weather forecasting
Nováková, Tereza ; Halenka, Tomáš (advisor) ; Žák, Michal (referee)
Testing and validation of the numerical prediction model is an important part of its usage for weather prediction. The simulations have been performed with model WRF (Weather Research and Forecasting), of which basic principles are described. The simulation was set up in reanalysis mode, i.e. with perfect boundary conditions, for one month, July of 2000. The simulation in hydrostatic approximation with 10 km resolution is compared to the simulation with one nested domain in non-hydrostatic mode with 2 km resolution. The study is aimed at the convective and stratiform precipitation in daily total amount of precipitation and compared to the total amount from observed data. In addition, a two-day weather forecast was validated. The forecast has been run daily since January 2016 at the Department of Atmospheric Physics. Standard deviation of 24 and 48 hour forecast is compared with GFS global model analysis. Powered by TCPDF (www.tcpdf.org)
|
|
|
Analysis and assessment of ensemble simulations of regional climate models in Europe for selected scenarios of greenhouse gases
Kluková, Zuzana ; Halenka, Tomáš (advisor) ; Belda, Michal (referee)
An analysis of the air temperature and precipitation for historical and future experiments of regional climate models from Euro-CORDEX activity is presented. A validation of models was performed for the time period 1989 - 2005 using the comparison of model results with E-OBS dataset which represents real values. For this period results show good agreement for temperature, much worse agreement appears for precipitation where their overestimation is more typical. The future evaluation based on the scenarios of greenhouse gases RCP4.5 and RCP8.5 was investigated for periods 2021 - 2050 and 2071 - 2100 in comparison with the period 1971 - 2000 as reference. For the simulations of the future climate we can notice an approximately linear increase of temperatures which is most significant in the northeast Europe. For precipitation models predict their increase in the north Europe and decrease in the south Europe.
|
|
|
Long-term variability of heat waves and cold spells in Central Europe
Lhotka, Ondřej ; Kyselý, Jan (advisor) ; Halenka, Tomáš (referee) ; Huth, Radan (referee)
Title: Long-term variability of heat waves and cold spells in Central Europe Author: Mgr. Ondřej Lhotka Department: Department of Physical Geography and Geoecology, Faculty of Science, Charles University in Prague Supervisor: RNDr. Jan Kyselý, Ph.D., Institute of Atmospheric Physics, Czech Academy of Sciences Abstract: Heat waves and cold spells have serious impacts on natural environment and society. The main aims of this thesis are to examine past variability of Central European heat waves and cold spells, to assess severity of recent events in a long-term context, to evaluate simulation of heat waves in climate models, and to construct their scenarios for a possible future climate. Heat waves and cold spells were primarily investigated as spatial events, using gridded data sets. E-OBS gridded data was utilized to assess past variability of heat waves and cold spells and to evaluate regional climate model (RCM) simulations from the ENSEMBLES and EURO-CORDEX projects. An extremity index that captures joint effects of temperature, duration, and spatial extent of individual heat waves and cold spells was proposed and tested. The persistent 1994 heat wave was found to be the most extreme over Central Europe in the 1950−2012 period, and the summer of 2013 was unprecedented at several Central European stations...
|
|
|
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,...
|
|
|
Analysis of Euro-CORDEX regional climate models results
Kluková, Zuzana ; Halenka, Tomáš (advisor) ; Belda, Michal (referee)
In this submitted barchelor's thesis an analysis of the air temperature and precipitation for regional climate models from Euro-CORDEX activity is performed for time period 1989 - 2008. Models are also compared with E-OBS dataset which represents real values. Specifically, models WRF331C (instituce BCCR), RegCM4-2 (CUNI), RegCM4-2 (DHMZ), WRFV35D (IDL), WRF331F (IPSL+INERIS), RACMO22E (KNMI), HadRM3P (Met Office), RCA4 (SMHI), WRF331G (UCAN), PROMES (UCLM) a CCLM-COSMO (WEGC) with resolution 0,11 and 0,44 degrees were considered for the analysis. The analysis is based on the comparison of annual courses, seasonal maps of model biases and Taylor diagrams. Results show good match of models with E-OBS for temperature, much worse agreement appears for precipitation. Temperatures are lower than E-OBS in winter and both higher and lower in summer. Precipitation is usually overestimated.
|
|
|
Modelling of exoplanetary atmospheric circulation
Novák, Jiří ; Brechler, Josef (advisor) ; Halenka, Tomáš (referee)
In this thesis we study the properties of exoplanetary atmospheres. The first part describes methods for searching exoplanets, statistics of discovered exoplanets and the sampling factors. The second part describes the properties of chosen planets and moons in the Solar system (Venus, Mars and Titan) and also possible properties of the exoplanetary atmospheres that are only briefly understood. The third part describes the atmospheric models which incorporate a full 3D model of the atmosphere, and a shallow- water model. We also show the results of exoplanetary atmospheric models published in the scientific journals. This part also describes the icosahedral geodetic grid that is advantageous for the global climatic models, and also discretisation on sphere and the application of the operators (gradient, divergence, vorticity) on geodetic grid. The last part is about creating program for global shallow water model in divergence-vorticity variables with forcing system with using icosahedral geodetic grid - we describe technical properties connected with model creating, parameters which the model uses during time integration, geographic system for results display and we show results for various kinds of extrasolar planets and planets in the Solar system. We used several numerical tests for testing model...
|
|
|
Global changes in the midlatitude stratosphere
Kozubek, Michal ; Laštovička, Jan (advisor) ; Halenka, Tomáš (referee) ; Metelka, Ladislav (referee)
Several phenomena in the middle latitude stratosphere are studied in the thesis. The reanalyses are utilized as a source of data for our study. Different reanalyses are compared each other and with observations and problems of reanalyses are shown. We are interested in connection between ozone, dynamics and other phenomena (Sudden Stratospheric Warmings, solar cycle, NAO etc.) in the stratosphere, mainly from 1979 to present using ERA-Interim, NCEP/NCAR reanalyses or satellite observations. The linear connection between total ozone difference and 100 hPa eddy heat flux is found in winter middle latitudes. Ozone trends in Europe and China are analysed. The meridional and zonal wind is also studied using MERRA reanalysis and model output (CCM SOCOL v3.0). The comparison of geographical distribution of geopotential height and meridional wind is done. Differences between MERRA and CCM SOCOL v3.0 has been observed for geopotential hight and meridional wind for winter season.
|
|
|
Regional Climate Modeling
Belda, Michal ; Halenka, Tomáš (advisor) ; Huth, Radan (referee) ; Metelka, Ladislav (referee)
Regional climate models are commonly used for downscaling global climate simulations to the regional scale using nested limited-area models. One of the main goals of this work was the application of regional model RegCM in very high resolution for the region with complex topography in the framework of EC FP6 project CECILIA. RegCM was employed to downscale climate change scenario simulations performed by ECHAM5 model according to the IPCC A1B emission scenario for Central and Eastern Europe in 10km resolution. Validation of model performance, assessed by nesting RegCM in ERA-40 reanalysis, shows improvement of regional climate patterns mainly in mountainous areas. Temperature is well represented with mostly cold bias around -1 žC. Precipitation is affected by large biases around 80 %, in mountainous areas up to 400 % overestimation in winter. Downscaled climate change signal shows average warming 0.51.5 žC in period 20212050 and 24 žC in period 20712100. Precipitation changes are mostly within ±0.5 mm/day. RegCM3beta version with adjusted precipitation scheme parameters shows improvement of the precipitation bias, difference in climate change is rather negligible. Experiments with different convection schemes of RegCM in a case study for Africa performed in the framework of CORDEX project are...
|
guest ::
