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Exploration of extraterrestrial body impact and UV-driven transformation of atmospheres of terrestrial planets
Knížek, Antonín ; Ferus, Martin (advisor) ; Kabáth, Petr (referee) ; Kopecký, Vladimír (referee)
Keywords: Exoplanets, Earth, Impact, Photochemistry, Infrared Spectroscopy, Atmospheric chemistry Impacts and photochemistry are two very important driving forces for chemical transformation of planetary atmospheres. While strong UV radiation produced by young stars continuously provides a significant amount of energy, impacts are one-time events with far-reaching consequences. Especially important are then impacts on young rocky planets, including the early Earth, because these planets are likely exposed to much higher impact fluxes, commonly called 'heavy bombardment'. This bombardment is the final echo of the turbulent planetary accretion and has prominent significance for planetary environments, e.g., the chemical composition and shape of the planetary surface, the chemistry of atmospheres, aerosol production, and likely the origin of life. Future observations of exoplanets by space telescopes, such as the James Webb Space Telescope or Ariel, as well as ground-based telescopes, such as the Extremely Large Telescope currently under construction in Chile, could determine whether this heavy bombardment represents a common scenario for the evolution of terrestrial planets. Both impacts and photochemistry can be efficiently simulated and studied in laboratory conditions by state-of-the-art methods....
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Emissions of isoprene by oil palm and their impacts on climate and composition of the atmosphere
Palouš, Daniel ; Albrechtová, Jana (advisor) ; Ponert, Jan (referee)
Biogenic volatile organic compounds (BVOC) serve many physiological and ecophysiological functions in plants, e.g. abiotic or biotic stress protection or signalling. Emission capacity and spectrum of emitted BVOC vary between plant species. Isoprene, having the highest global annual emission among all BVOC, has considerable influence on atmospheric chemistry and its processes. Isoprene contributes to secondary organic aerosol formation. Under specific conditions reaction of isoprene and NOx may lead to ground-level ozone formation. Isoprene also affects oxidative capacity of the atmosphere. Oil palm (Elaeis guineensis Jacq.) is a rapidly expanding crop and it is a strong isoprene emitter. Most of the global cultivation of oil palm is located in a relatively small region in southeast Asia posing a risk to regional air quality. To prevent ground-level ozone formation, keeping ground-level NOx concentrations low in the regions of oil palm cultivation is crucial. Models of global isoprene emission vary greatly and not all of them take oil palm cultivation in account. The present thesis aims to cover current knowledge on physiological functions of isoprene's synthesis and emission with regard to oil palm cultivation and ecological implications of mentioned processes. The thesis includes also brief...
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Investigation of photodissociation dynamics implementing the velocity map imaging technique
Moriová, Kamila ; Fárník, Michal (advisor) ; Profant, Václav (referee)
The aim of this thesis is to investigate the effects of change in the chain length and chlorine group position on C-Cl bond photodissociation dynamics of chloroalkanes using the velocity map imaging (VMI) method. Three different chloroalkanes are studied (1-chloropropane, 2-chloropropane, 1-chloropentane) and compared with previously investigated chloromethane. Regardless of the parent chloroalkane, measured kinetic energy distributions (KEDs) of chlorine photofragments exhibit a single peak at energy around 0.8 eV. Photodissociation of higher chloroalkanes involves a recoil of a semi-rigid alkyl fragment, whose internal energy absorbs 40-60% of the total available energy. For chloromethane, however, only less than 10% of the available energy goes into the alkyl fragment excitation. Measured results of the energy partitioning are compared with cal- culations based on classical impulsive models. VMI experiment in combination with theory also yields information about the nature of electronic transition and probability of the intersystem crossing. Analysis indicates that the direct absorp- tion into the triplet state is more probable for the chloroalkanes with longer chain length, especially for the branched one. 1
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Study of tropospheric chemistry using regional climate model RegCM4 and chemistry transport model CAMx
Bartík, Lukáš ; Huszár, Peter (advisor) ; Bednář, Jan (referee)
The subject of this diploma thesis is study of the impacts of different implementations of turbulence and convection in the Regional Climate Model (RegCM, version 4.6) on the ability to predict the chemical pollution of the troposphere in Europe, which was simulated by the chemical transport model CAMx (Comprehensive Air quality Model with extensions, version 6.50) driven by RegCM meteorology using offline coupling of theese two models. Thesis also includes a brief description of the tropospheric chemistry, a discussion of the influence of meteorological conditions on changes in pollutant concentrations in the troposphere, a brief introduction to the regional climate modeling, a description of both models and method of their coupling. The main focus of the thesis is the analysis of the impacts of different parameterizations in RegCM model simulations on some climatic elements, validation of air temperature and precipitation, analysis of the impacts of changes in driving meteorology on ozone, nitrogen dioxide, sulfur dioxide and fine aerosol, validation of model concentrations of these pollutants with measurements at rural monitoring stations and comparison of column concentrations of nitrogen dioxide with satellite measurements.
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Emissions of isoprene by oil palm and their impacts on climate and composition of the atmosphere
Palouš, Daniel ; Albrechtová, Jana (advisor) ; Ponert, Jan (referee)
Biogenic volatile organic compounds (BVOC) serve many physiological and ecophysiological functions in plants, e.g. abiotic or biotic stress protection or signalling. Emission capacity and spectrum of emitted BVOC vary between plant species. Isoprene, having the highest global annual emission among all BVOC, has considerable influence on atmospheric chemistry and its processes. Isoprene contributes to secondary organic aerosol formation. Under specific conditions reaction of isoprene and NOx may lead to ground-level ozone formation. Isoprene also affects oxidative capacity of the atmosphere. Oil palm (Elaeis guineensis Jacq.) is a rapidly expanding crop and it is a strong isoprene emitter. Most of the global cultivation of oil palm is located in a relatively small region in southeast Asia posing a risk to regional air quality. To prevent ground-level ozone formation, keeping ground-level NOx concentrations low in the regions of oil palm cultivation is crucial. Models of global isoprene emission vary greatly and not all of them take oil palm cultivation in account. The present thesis aims to cover current knowledge on physiological functions of isoprene's synthesis and emission with regard to oil palm cultivation and ecological implications of mentioned processes. The thesis includes also brief...
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Coupling atmospheric chemistry/aerosols to regional climate models
Huszár, Peter ; Halenka, Tomáš (advisor) ; Macoun, Jan (referee) ; Eben, Kryštof (referee)
Title: Coupling atmospheric chemistry/aerosols to regional climate models Author: Peter Huszár Department: Department of Meteorology and Environment Protection Supervisor: doc. RNDr. Tomáš Halenka, CSc. Supervisor's e-mail address: tomas.halenka@mff.cuni.cz Abstract: In this thesis, the connections between air quality and climate are studied. For this purpose, regional climate model RegCM3 and chemistry transport model CAMx has been coupled offline with one- and two-way interaction. Our work represents a first attempt to connect RegCM3 not only with CAMx, but with any other chemistry transport model. As a first step, an offline one way couple of RegCM3 and CAMx has been developed, meaning that the climate model drives the transport, emission, chemical transformation and deposition of species while the radiative feedbacks of gases and aerosols are not considered. A meteorological interface has been developed at our department in order to convert the meteorological data generated by RegCM3 to fields required by CAMx. For those parameters that are essential for CAMx but the regional climate model does not supply them, diagnostic methods were implemented into this interface. Further, it is used to calculate biogenic emissions. Regarding anthropogenic emissions, a simple utility has been developed to...
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Fotochemie v klastrech a nanočásticích: systémy relevantní v atmosférické chemii a v biologii
Fárník, Michal
Influence of solvation on photodissociation of molecules is investigated in clusters produced in a molecular beam experiment. Photochemistry in three different systems is compared: (i) HBrArn and (HBr)n clusters, where the fragment does not react with the solvent and an effect of the fragment caging is observed, (ii) HBr(H2O)n system where chemical reaction occurs and a reaction channel is closed by the electronic interaction with the solvent. The practical relevance of the studied processes ranges from atmospheric chemistry to biology.
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