Temperature inversions in the boundary layer over Prague

Temperature inversions in the boundary layer over Prague Abstract The main objective of this study is to analyze temperature inversions in the atmospheric boundary layer (ABL) over Prague. In the first part, the concept of the ABL is defined and main theoretical aspects of air stratification are explored. The main part of the background research summarizes current knowledge of temperature inversions, especially how the landscape pattern influences their development and parameters under different synoptic situations, and methods used for their detection, measurement and evaluation. Considering the theme of the thesis, main geographic factors influencing temperature inversions in the area of Prague are also defined. The focus of actions is placed on inversions analysis based upon time series of Praha-Libuš rawinsonde station. Homogeneity of used data is tested and all inversions within the 2000- meters-thick-layer close to the ground are derived. Diurnal, annual and interannual frequency variations are described. Significance of long-term trends is tested and trends are compared to data from Prostějov and Kümmersbruck stations. Keywords: temperature inversions, boundary layer, climate, Pragu

Long-term trends of wind velocity in Bohemia

Department of Physical Geography and GeoecologyKatedra fyzické geografie a geoekologieFaculty of SciencePřírodovědecká fakult

The application of atmospheric circulation classifications in the interpretation of climate model outputs

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..

Využití klasifikací atmosférické cirkulace v interpretaci výstupů z klimatických modelů

Využití klasifikací atmosférické cirkulace v interpretaci výstupů z klimatických modelů Mgr. Jan Stryhal Automatizované klasifikace polí atmosférické cirkulace (zkráceně cirkulační klasifikace) jsou nástrojem hojně užívaným v synoptické a dynamické klimatologii ke studiu atmosférické cirkulace a vazeb mezi atmosférickou cirkulací a nejrůznějšími atmosférickými, environmentálními a společenskými jevy. Aplikace cirkulačních klasifikací na výstupy dynamických modelů atmosféry prodělaly od prvních studií před zhruba 30 lety značný rozvoj, odrážející rychlý rozvoj statistiky, výpočetní techniky a přirozeně také klimatologického výzkumu, který se tváří v tvář paradigmatu antropogenních klimatických změn stává více a více závislým na simulacích atmosféry. Nekoordinované využívání nejrůznějších statistických přístupů v analýze výstupů globálních modelů klimatu a jejich ensemblů a nahodilý výběr cirkulačních proměnných, prostorových a časových domén a referenčních datových souborů vyústily v potřebu srovnávacích studií, které by objasnily, nakolik je srovnání klasifikací ve dvou datových souborech citlivé k subjektivním volbám. Tato práce reaguje na tuto potřebu zaměřením na roli, jakou hrají v podobných výzkumech volba klasifikační metody a v případě validace modelů volba referenční reanalýzy atmosféry. Za...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...Katedra fyzické geografie a geoekologieDepartment of Physical Geography and GeoecologyPřírodovědecká fakultaFaculty of Scienc

Klasifikace atmosférické cirkulace

The goal of the present article is to provide a brief overview of the development and usage of classifications of atmospheric circulation, particularly classifications of circulation patterns. In the first section, the motivation to conduct research into atmospheric circulation and the role of classifications in this research are discussed. In addition, basic approaches to classification are described. In the second section, manual classification methods are introduced; the focus is on those methods that have been widely used in the Czech literature - the synoptic catalogues of Brádka and Hess-Brezowsky. To our knowledge, such an overview has not been published yet. In the third section, the development of automated methods is described and the most commonly used methods are briefly introduced. We conclude with an overview of one of the fastest developing fields in synoptic climatology - the application of circulation classifications to climate modelling.30032

Properties of tin/plasma polymer nanocomposites

Thin composite layers (tin in plasma polymer matrix) were prepared in a stainless steel vacuum chamber. An RF powered magnetron with tin target was used to excite the discharge and to activate the monomer species (n-hexane). The gas mixture introduced comprised At and n-hexane vapours. The properties of the films and chemical composition were characterized by AFM (surface morphology), TEM and Electron tomography (bulk structure characterization), XPS and FTIR spectroscopy (chemical composition analyses). Current-voltage characteristics were measured to examine the electrical properties of the layers and their dependence on the deposition parameters

Growth and modification of organosilicon films in PECVD and remote afterglow reactors

International audienceFive hundred nanometer thick organosilicon coatings are prepared on Si substrates in parallel by the plasma-assisted polymerisation of hexamethyldisiloxane (HMDSO) in an RF-inductively coupled plasma (RFICP) and distributed electron cyclotron resonance plasma (DECRP) at low pressure (0.27 Pa) and of tetramethyldisiloxane (TMDSO) premixed with oxygen in an N2 microwave induced remote afterglow (MIRA) at 560 Pa. The structure of these different films is analyzed by different techniques, such as Fourier-transform infrared spectroscopy, Rutherford backscattering spectrometry, atomic force microscopy, ellipsometry, and contact angle measurements. Results of the film composition (at least 30% carbon content), optical properties, and morphology indicate a low cross-linking degree accompanied by short chain length for RFICP and DECRP films, in contrast to a high-molecular-weight structure observed for the MIRA film. Carbon removal is achieved within the same plasma reactors by further oxygencontaining plasma treatment performed in the RF-ICP (3.33 Pa), DECRP (0.27 Pa, ~200 V biased substrate), and MIRA (N2/O2 (98.7:1.3, 560 Pa)) reactors. The same measurements are carried out on the treated samples in order to detect the main changes in film composition, optical properties, and morphology. The evolution of surface energy is also studied. The results are discussed according to film structure and process specificity. O/Si and C/Si elemental ratios calculated from RBS analysis for an as-deposited RF-inductively coupled plasma coating (RFICP) and films post-treated by N2/O2 microwave induced remote afterglow (MIRA), O2 RFICP and O2 distributed electron cyclotron resonance plasma (DECRP, biased sample) processes

Temporal and spatial variability of surface-based inversions over Europe based on ERA-Interim reanalysis

Tropospheric temperature inversions seem to be an important feature of climate, as well as a significant factor affecting air quality and fog formation. The aim of this article is to investigate the temporal and spatial variability of surface-based inversions (SBIs) over Europe. It is based on data derived from the ERA-Interim reanalysis for the period 1981-2015. The study examines diurnal, seasonal and multiannual variability of temperature inversions based on their frequency, depth and strength. These three parameters are characterized by strong temporal variability - diurnal and seasonal, as well as strong spatial differentiation. It has been confirmed that the energy budget is the key factor responsible for diurnal, and partly seasonal variability of SBI occurrence. Its negative values lead to an intense cooling of active surface and initiate the formation of the radiative inversions, which are the most common type of inversion occurring over the mainland of Europe. Temperature inversions usually form shortly after dusk, increasing gradually their depth and strength until sunrise. At 0000 Universal Time Coordinated (UTC), SBI frequency attains higher values in the summer than in the winter over the predominant part of Europe. However, the inversion layers occurring then are noticeably shallower and weaker. Surface type strongly affects SBI properties. This is mostly marked in terms of the distinct differentiation between marine and land areas as well as the impact of vast glaciers located across Greenland and western part of Iceland. Moreover, the distribution of SBI depth and strength is shaped by atmospheric circulation. For instance, their higher values occur over Eastern Europe in the winter, which is associated with the influence of a seasonal high pressure system found over Russia. Taking into account multiannual variability, SBI parameters, primarily depth and strength, exhibit the most significant negative changes in the winter

Massive allografts in tumour surgery

We offer our personal experience of the use of massive bone allografts after tumour resection. We demonstrate the long-term results from 71 patients (72 allografts) operated on between 1961 and 1990. The long-term survival rate in osteoarticular and intercalary grafts is around 60%. Fractures of the graft can be salvaged in most cases. Infection leads to the removal of the graft in almost all cases. Factors influencing the survival, remodelling and complications of the grafts are discussed. The regime of cryopreservation, fixation and loading of the graft influence these factors, as do the use of autologous bone chips around the allograft–host junction and the application of chemotherapy or radiation. Fracture of the graft can be salvaged in most cases, as opposed to infection which remains the most severe complication and can occur at any time. Even with the improvement of tumour endoprostheses, the use of allografts remains an option, especially in young patients