A model of the lithosphere thickness in the region of the Carpathians     

Pavel Pajdušák  Jaroslava Plomerová  Vladislav Babuška  Reviewer Č. Tomek 《Studia Geophysica et Geodaetica》1989,33(1):11-21

Summary Directionally independent average P residuals computed for waves of teleseismic events arriving under various azimuths and incidence angles provided the basis for estimating the lithosphere thickness beneath the Carpathians and their surroundings. A thin lithosphere (60–80 km) was determined for the Pannonian Basin and the Transylvanian Basin, the thickest lithosphere(about 180 km) beneath the South Carpathians at the contact with the Moesian Platform. In other parts of the Carpathian belt the lithosphere thickens beneath the outer parts towards the SW margin of the East-European and the Moldavian Platforms. The lithosphere thicknesses derived from P residuals correlate well with the magnetotelluric determinations of a layer of increased electrical conductivity in the upper mantle.

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Резюме Осре?rt;ненные временные невязкu Р волн, незaвuсuмые оm нanрaвленuя u рaссчumaнные ?rt;ля у?rt;aленных землеmрясенuŭ uз волн, nрuхо?rt;ящuх nо?rt; рaзнымu aзuмуmaмu u у лaмu na?rt;енuя, ?rt;aюm основaнuе ?rt;ля оnре?rt;еленuя мощносmu лumосферы Кaрnam u uх окресmносmеŭ. Тонкaя лumосферa(60–80 км) оnре?rt;еленa ?rt;ля Пaннонско о u Трaнсuльвaнско о бaссеŭнов, a сaмaя мощнaя лumосферa(около 180 км) нaхо?rt;umся nо?rt; Южнымu Кaрnamaмu. В ?rt;ру uх чaсmях Кaрnamско о nоясa мощносmь лumосферы нaрaсmaеm во внешнuх зонaх в нanрaвленuu к ю о-зana?rt;ноŭ окрauне Восmочно-Евроnеŭскоŭ u Мол?rt;aвскоŭ nлamформ. Нaблю?rt;aеmся хорошaя корреляцuя мощносmu лumосферы, оnре?rt;еленноŭ нa основе невязок временu Р волн, с мa нumоmеллурuческuмu ?rt;aннымu nо лубuне слоя nовышенноŭ элекmроnрово?rt;uмосmu в верхнеŭ мaнmuu.

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Transverse oscillations produced at collision of two plasma streams     

Jaroslava Hrušková 《Studia Geophysica et Geodaetica》1964,8(4):347-351

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Climate Change Projections Based on GCM-Simulated Daily Data     

Ivana Nemešová  Jaroslava Kalová  Martin Dubrovský 《Studia Geophysica et Geodaetica》1999,43(2):201-222

Three-dimensional general circulation models (GCMs) are 'state-of-the-art' tools for projecting possible changes in climate. Scenarios constructed for the Czech Republic are based on daily outputs of the ECHAM-GCM in the central European region. Essential findings, derived from validating, procedures are summarized and changes in variables between the control and perturbed experiments are examined. The resulting findings have been used in selecting the most proper methods of generating climate change projections for assessing possible hydrological and agricultural impacts of climate change in selected exposure units. The following weather variables have been studied: Daily extreme temperatures, daily mean temperature, daily sum of global solar radiation, and daily precipitation amounts. Due to some discrepancies revealed, the temperature series for changed climate conditions (2×CO ₂ ) have been created with the help of temperature differences between the control and perturbed runs, and the precipitation series have been derived from an incremental scenario based on an intercomparison of the GCMs' precipitation performance in the region. Solar radiation simulated by the ECHAM was not available and, therefore, it was generated using regression techniques relating monthly means of daily extreme temperatures and global radiation sums. The scenarios published in the paper consist of monthly means of all temperatures, their standard deviations, and monthly means of solar radiation and precipitation amounts. Daily weather series, the necessary input to impact models, are created (i) by the additive or multiplicative modification of observed weather daily series or (ii) by generating synthetic time series with the help of a weather generator whose parameters have been modified in accord with the suggested climate change scenarios.  相似文献   

Regional fabric of the deep lithosphere in central Europe from seismic anisotropy     

Vladislav Babuška  Jaroslava Plomerová 《Studia Geophysica et Geodaetica》1995,39(3):219-226

Summary The large scale anisotropic structures with plunging symmetry axes in the subcrustal lithosphere of central Europe were derived from independent observations of teleseismic P-residual spheres and polarizations of the split SKS waves. The dipping structures are interpreted as remnants of palaeo-subduction systems which retain olivine orientations from ancient oceanic lithosphere. Values of k_P and k_S estimated from observed teleseismic P and SKS data are within the range of anisotropies found for the upper mantle rocks. The Variscides of central Europe may thus be characterized by two palaeo-subduction systems, with symmetry axes divergent relative to the suture between the Moldanubicum and Saxothuringicum.  相似文献   

Geodynamics of Lithosphere and Earth’s Mantle: Seismic Anisotropy as a Record of the Past and Present Dynamic Processes   总被引：1，自引：0，他引：1  

Jaroslava Plomerová  Robert C. Liebermann  Vladislav Babuška 《Pure and Applied Geophysics》1998,151(2-4):213-219

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Seismic Anisotropy and Velocity Variations in the Mantle beneath the Saxothuringicum-Moldanubicum Contact in Central Europe   总被引：1，自引：0，他引：1  

J. Plomerová  V. Babuška  J. Šílený  J. Horálek 《Pure and Applied Geophysics》1998,151(2-4):365-394

—We report on results of a passive seismic experiment undertaken to study the 3-D velocity structure and anisotropy of the upper mantle around the contact zone of the Saxothuringicum and Moldanubicum in the western margin of the Bohemian Massif in central Europe. Spatial variations of P-wave velocities and lateral variations of the particle motion of split shear waves over the region monitor changes of structure and anisotropy within the deep lithosphere and the asthenosphere. A joint interpretation of P-residual spheres and shear-wave splitting results in an anisotropic model of the lithosphere with high velocities plunging divergently from the contact of both tectonic units. Lateral variations of the mean residuals are related to a southward thickening of the lithosphere beneath the Moldanubicum.  相似文献   

On one method of solving the two-dimensional direct magnetic problem     

Jaroslava Sisáková 《Studia Geophysica et Geodaetica》1990,34(1):32-36

Summary In this paper the solution of the direct magnetic problem for two-dimensional bodies, founded on the application of Green's theorem is derived. This solution is derived under the assumption that the components of the magnetization vector have continuous derivatives with respect to the coordinates and that they are continuous within the body. The problem is solved in terms of Green-type integrals for the scalar and vector potential of the magnetostatic field and it may serve the purpose of solving the problem of the analytical continuation of the external field into the body.  相似文献   

Performance of ALADIN-Climate/CZ over the area of the Czech Republic in comparison with ENSEMBLES regional climate models     

Lenka Crhová  Eva Holtanová  Jaroslava Kalvová  Aleš Farda 《Studia Geophysica et Geodaetica》2014,58(1):148-169

Nowadays Regional Climate Models (RCMs) are increasingly used for downscaling of information from the coarse resolution of global climate models (GCMs) and they represent a more and more popular tool for assessment of future climate changes and their impacts at regional scales. In spite of continual progress of RCMs, their outputs still suffer from many uncertainties and biases. Therefore, it is necessary to assess their ability to simulate observed climate characteristics and uncertainties in their outputs before they are applied in subsequent studies. In the present study, the assessment of RCM performance in simulating climate in the reference period of 1961–1990 over the area of Czech Republic is presented. Furthermore, we focused on the intercomparison of the models’ results, mainly on the comparison of the Czech model ALADIN-Climate/CZ with outputs of other RCMs. Simulation of ALADIN-Climate/CZ in 25-km horizontal resolution, and thirteen RCM simulations from the ENSEMBLES project were assessed. Attention was paid especially to comparison of simulated and observed spatial and temporal variability of several climatic variables. The monthly and seasonal values of surface air temperature, precipitation totals and relative humidity were examined for evaluation of temporal variability and 30-year seasonal and monthly values with respect to spatial variability. Climate model performance was evaluated in several ways, namely by boxplots, maps of variability characteristics, skill scores based on mean square error and Taylor diagrams. Model errors detected by model evaluation depend on many factors (e.g. considered variables and their characteristics, area of analysis, time scale of interest and the method of assessment). On the basis of incorporated performance criteria model ALADIN-Climate/CZ belonged to a better group of RCMs in most cases. However, it was definitely the worst in simulating spring monthly means of air temperature and relative humidity in all seasons.  相似文献   

Cyanobacterial blooms in Lake Atitlan, Guatemala     

Eliška Rejmánková  Ji?í Komárek  Margaret Dix  Jaroslava Komárková  Nancy Girón 《Limnologica》2011,41(4):296-302

Lake Atitlan, one of the most important lakes not only in Central America but in the whole world, is facing serious problems with increasing water pollution. Over the last several decades, the uncontrolled nutrient input into the lake has lead to high P levels and low N:P ratios, initiating cyanobacterial blooms. The first bloom occurred in December of 2008, followed by more extensive bloom in October 2009. The blooms are formed by cyanobacteria from the rare planktic Lyngbya hieronymusii/birgei/robusta complex. Based on the species morphology, the Atitlan population corresponds to L. robusta and this is the first case of reported bloom of this species worldwide. Remote sensing images documented that at the maximum bloom development, 40% of the 137 km² of the lake area were covered by dense patches of Lyngbya, with the chlorophyll a concentration reaching over 100 μg L⁻¹. The only toxins detected in the 2009 bloom were trace levels of cylindrospermopsin and saxitoxin with 12 and 58 ng g⁻¹, respectively. The nitrogen fixation followed a pattern expected in non-heterocytous cyanobacteria, i.e., the nitrogenase activity was minimal during the day, while during the night the activity reached 2.2 nmol C₂H₄ μg Ch a⁻¹ h⁻¹. Delta ¹⁵N of −0.86‰ was well in the range given for nitrogen fixing organisms. The cell C, N and P content was 36.7%, 5.9% and 0.9%, respectively, resulting in the molar ratio of 105:14.4:1. A well designed and executed lake monitoring program, strict control of nutrient input into the lake, and public education are the necessary prerequisites for potential prevention of even more severe blooms than the one from 2009.  相似文献   

Holocene marine terraces on two salt diapirs in the Persian Gulf,Iran: age,depositional history and uplift rates     

Ji&#x;í Bruthans  Michal Filippi  Milan Ger&#x;l  Mohammad Zare  Jaroslava Melkov  Anna Pazdur  Pavel Bosk 《第四纪科学杂志》2006,21(8):843-857

Slightly inclined Holocene marine terraces cover parts of two circular salt diapirs (Hormoz and Namakdan) in the Persian Gulf. Their relative altitude above present sea level results from a combination of general marine transgression/regression affecting the whole area, and of local uplift related to salt diapirism. Differential uplift rate of the studied diapirs in centre‐to‐rim profiles was calculated from results based on: (i) radiocarbon ages of skeletal remains of benthic faunas (19 samples), which originally grew close to sea level; (ii) original altitude of samples, estimated from general sea‐level oscillation curves for the last 10 kyr, and (iii) present sample altitude measured in the field. Calculated uplift rates increase from rim to centre on both diapirs in the range from: 2 mm yr^?1 at the rim to 5–6 mm yr^?1 at the interior of Hormoz, and 1–3 mm yr^?1 at the rim to 3–5 mm yr^?1 at the interior of Namakdan. Such uplift rate distributions fit into the parabolic profile of Newtonian fluid rather than to profiles typical for pseudoplastic fluids. The increase in uplift rate with distance from rim to centre of diapirs is gradual as demonstrated also by generally smooth surface of marine terraces. No tectonic dissections were found. The depositional history on both salt diapirs is similar although they are situated more than 100 km apart. Marine sedimentation started at about 9.6k cal. yr BP on Hormoz and at 8.6k cal. yr BP on Namakdan. Owing to rapid transgression, the sea partially truncated both salt diapirs and rapidly deepened, and carbonate mud was deposited on the peripheries of both salt diapirs. Between 7 and 5k cal. yr BP beach deposition replaced carbonate mud. Soon after 5k cal. yr BP, the sea retreated from most of the marine terraces on both salt diapirs. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献