A remark on ‘effects associated with the sector boundary crossing on July 8, 1966’ by Z. Švestka     

L. Křivský 《Solar physics》1968,4(3):373-374

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Reviews     

Petr Holota  Georgij Karský 《Studia Geophysica et Geodaetica》1991,35(2):130-132

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Comparison of Solar and Geomagnetic Activity Effects on the Northern Hemisphere Weather Changes     

Bochníček  Josef  Hejda  Pavel  Pýcha  Josef 《Studia Geophysica et Geodaetica》2001,45(2):133-154

The changes of pressure and temperature fields in the winter lower troposphere observed in association with changes in solar and/or geomagnetic activity are compared. It is shown that the fact whether it was solar or geomagnetic activity was not so important as whether the levels of the two activities were high or low. The differences between the effects of solar/geomagnetic activity, however, are revealed, the pressure and temperature data being stratified according to the QBO phase. The relationship obtained are discussed from the viewpoint of mechanisms resting upon both the planetary wave propagation and the changes of atmospheric air currents in the global electric circuit.  相似文献   

Extremely high demands for measurement accuracy in precise determination of frequency-dependent magnetic susceptibility of rocks and soils     

František Hrouda  Jiří Pokorný 《Studia Geophysica et Geodaetica》2011,55(4):667-681

Frequency-dependent magnetic susceptibility, which is an important tool for environmental and palaeoclimatologic research, is usually relatively low, mostly less than 15% of the low frequency value and there is a demand for high precision of its measurement. The accuracy required for the susceptibility measurement at individual operating frequencies for precise determination of the parameter characterizing the frequency-dependent susceptibility was investigated theoretically and also experimentally through repeated measurement of artificial specimens and sediments of a loess/palaeosol sequence using the MFK1 Kappabridge. It was found that the variation in the frequency-dependence in the order of 1% is well reproducible and the measurements can be interpreted in terms of magnetic granulometry even in weakly magnetic materials.  相似文献   

The surface urban heat island in the city of Brno (Czech Republic) derived from land surface temperatures and selected reasons for its spatial variability     

Petr Dobrovolný 《Theoretical and Applied Climatology》2013,112(1-2):89-98

Thermal infrared images from Landsat satellites are used to derive land surface temperatures (LST) and to calculate the intensity of the surface urban heat island (UHI) during the summer season in and around the city of Brno (Czech Republic). Overall relief, land use structure, and the distribution of built-up areas determine LST and UHI spatial variability in the study area. Land-cover classes, amount and vigor of vegetation, and density of built-up areas are used as explanatory variables. The highest LST values typically occur in industrial and commercial areas, which contribute significantly to surface UHI intensity. The intensity of surface UHI, defined as the difference between mean LST for urban and rural areas, reached 4.2 and 6.7 °C in the two images analyzed. Analysis of two surface characteristics in terms of the amount of vegetation cover, represented by normalized difference vegetation index, demonstrates the predominance of LST variability (56–67 % of explained variance) over the degree of urbanization as represented by density of buildings (37–40 % of LST variance).  相似文献   

Projected evolution of circulation types and their temperatures over Central Europe in climate models     

Eva Plavcová  Jan Kyselý 《Theoretical and Applied Climatology》2013,114(3-4):625-634

The study deals with changes in large-scale atmospheric circulation (represented by circulation types) and associated surface air temperatures as projected in an ensemble of regional climate models (RCMs) from the ENSEMBLES project. We examine changes of circulation type frequencies and means of daily maximum and minimum temperatures within circulation types in individual seasons for two time slices of transient runs under the SRES A1B scenario (2021–2050 and 2071–2100) with respect to the control period (1961–1990). To study the influence of driving data, simulations of the driving general circulation models (GCMs) also are evaluated. We find that all models project changes of atmospheric circulation that are statistically significant for both future time slices. The models tend to project strengthening of the westerly circulation in winter and its weakening in summer. We show that increases of daily maximum and minimum temperatures in all seasons differ for individual circulation types. There are, however, only few features of the projected changes in the future circulation–temperature links that are common among the models, in particular relatively smaller warming for westerly types. Only in winter, projected changes in circulation types tend to contribute to the projected overall warming. This effect is negligible and mostly opposite in the other seasons. We also detect a strong influence of driving data on RCMs’ simulation of atmospheric circulation and temperature changes.  相似文献   

Stability problems in road and pipeline constructions and their mitigation — Examples from Sakhalin and Azerbaijan     

NOVOTNY Jan 《山地科学学报》2011,8(2):307-313

The paper gives two examples of larger construction projects with typical stability problems. The first example is from Sakhalin Island in the Russian Far East. It is connected with a construction of oil and gas pipelines through the mountainous terrain in Makarov region. The region has an active geotectonic history and is highly affected by uncontrolled erosion and extensive landslips. Basic principles of landslide hazard mitigation are presented. The second example is from a motorway construction in Azerbaijan. This motorway leads from Baku to Russia through a seismo-tectonically active area at the toe of Caucasian mountains and in some places is situated in deep cuts at the toe of high slopes. This unsuitable routing, together with seismic activity, led to a slope stability failure of a slope affected by recent tectonic movements near the village of Devechi. Stability conditions and designed remedy measures are presented.  相似文献   

High-Resolution Time Profiles of Fiber Bursts at 1420 and 2695 MHz     

P. Zlobec  M. Karlický 《Solar physics》2014,289(5):1683-1699

To obtain constraints for models of fiber bursts, high-resolution time (0.01 s) profiles of the fiber bursts recorded at 1420 and 2695 MHz by the Trieste radiometers are studied in detail. The fiber bursts were identified using Ond?ejov radio spectra. During the years 2000?–?2005, 18 intervals with fiber bursts were selected; 26 groups were defined and about 700 fibers were analyzed in detail. More than 300 pulsations, present almost simultaneously with the fibers, were also selected and studied in order to find similarities or differences between these two types of fine structures. It was found that the polarization of the associated continuum, both for fiber bursts and pulsations, is practically the same. Evaluating the ratio between absorption over emission of many single fibers we found that this parameter is very different even for nearby bursts; however, we realized that this ratio shows a tendency to decrease with time. Finally, the time profile of one selected fiber burst was fitted using a recent model based on the modulation of the broadband radio emission by fast magnetoacoustic waves. The results are discussed.  相似文献   

Polarization of the white-light corona and its large-scale structure in the period of solar cycle maximum     

O. G. Badalyan  M. A. Livshits  J. Sýkora 《Solar physics》1993,145(2):279-290

Distributions of brightness and polarization,p, were obtained for the February 16, 1980 solar corona. Isophotes have a circular shape, typical for the period of the solar cycle maximum. A variety of structural features are distinctly seen in the distribution ofp. The polarization reaches 55%, and thep values are comparatively high, not only in the well-defined streamers, but in the overlapping faint rays and small streamers, as well. A theoretical interpretation of the observed high degrees of polarization, taking into account the data on coronal brightness, is very difficult. This cannot be done within the scope of spherically symmetric models of the corona; the assumption of a high concentration of coronal matter into the plane of the sky is needed. With the most extreme densities in coronal structures, it is not, however, possible to exceed the observed valuep = 55%. Taking into account the accuracy of the polarization measurements, there are no reasons to reject the Thomson scattering as a basic mechanism to explain the origin of the white-light corona.  相似文献   

Ring Current Formed During the Bombardment of a Rotating Gas Torus by Neutral Beams     

Marian Karlický 《Astrophysics and Space Science》1997,257(2):249-257

A new mechanism for the generation of the electric ring current is presented. During the radial bombardment of a rotating gas torus by a neutral beam, electrons and protons are dragged by rotating gas. Due to collisions electrons obtain the torus velocity faster than protons, therefore in some layer there is a difference in electron and proton beam toroidal velocities; the electric current is thus generated. This current is discussed as the seed magnetic field in early stages of evolving galaxies, which is then amplified by the dynamo process to present values of the magnetic field. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献