Mechanism of solar-terrestrial relations and changes of atmospheric circulation     

Václav Bucha  Reviewer F. Rein  Reviewer J. Bochníček 《Studia Geophysica et Geodaetica》1977,21(3-4):350-360

Summary As a result of investigating the relations between the variations of geomagnetic activity and meteorological factors [1, 2] a mechanism of solar-terrestrial relationships and a model of the changes of atmospheric circulation in the Northern Hemisphere are proposed; this provides an explanation of the causes of the fluctuation of the climate, of dry and cold periods and differing vegetation conditions in various years in dependence on the intensity of geomagnetic activity.  相似文献   

Rift tectonics development in the light of geophysical data: Red sea region     

Miroslav Krs  Reviewer V. Bucha 《Studia Geophysica et Geodaetica》1977,21(3-4):342-350

Summary The paper discusses geophysical phenomena observed over tholeiitic dykes detected in the Eastern Desert of Egypt (Nubian Block). The dykes show specific physical properties and are either normally or reversely polarized along their whole length over 120 km. Dykes of similar properties may also be interpreted from airborne geophysical maps in Saudi Arabia (Arabian Block). Magnetic fields of the tholeiitic dykes were interpreted quantitatively: they fit the magnetic pattern over the Red Sea. The study emphasizes those geophysical phenomena which may serve as criteria for recognition of regions with rift tectonics development.  相似文献   

Structure and evolution of the geomagnetic field based on archaeomagnetic data     

S. P. Burlatskaya  Reviewer V. Bucha 《Studia Geophysica et Geodaetica》1974,18(1):79-82

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Book Review : Global Change and History of Geophysics. Edited by W. Schröder and M. Colacino. Interdivisional Commission on History of IAGA and History Commission of the German Geophysical Society,Bremen - Roennebeck 1996, 293 pp.     

Bucha  Václav 《Studia Geophysica et Geodaetica》1997,41(1):89-90

Studia Geophysica et Geodaetica -  相似文献   

Geomagnetic activity and the North Atlantic Oscillation     

Václav Bucha 《Studia Geophysica et Geodaetica》2014,58(3):461-472

The North Atlantic Oscillation (NAO) is the prominent pattern of winter climate variability that has a strong effect on weather in the North Atlantic region and the adjacent continents. At present, uncertainty prevails as to the mechanisms controlling the variability of the NAO. It is also difficult to explain why the positive phase of the NAO has prevailed over the past 37 years (1972–2008). We found high positive correlation coefficients between geomagnetic activity (used as a measure of solar wind intensity) and the NAO indices that equal 0.76 for 1962–1994 and 0.63 for 1961–2011. Positive correlations of the distribution of surface air temperature with the NAO and similarly with geomagnetic activity occur in the Northern Hemisphere. These results encourage our search for possible causes controlling the NAO. We have found that at times of high geomagnetic activity the NAO index is positive and magnetic reconnection may enable the solar wind to initiate downward winds in the magnetosphere. Wind anomalies originate at the edge of the stratospheric polar vortex and propagate downward through the troposphere taking part in the intensification of the vortex and of the westerlies. Stronger northerly winds over Greenland carry cold air southward and, together with the enhanced westerlies, advect the warm air from the Atlantic along the deep Icelandic low into Eurasia increasing temperatures there. On the other hand, at times of low geomagnetic activity, the NAO index is negative and the stratospheric polar vortex is weak. Warm air from the subtropics is carried into the Arctic and a rapid amplification of planetary waves propagating upward may cause displacement or even splitting of the weak vortex and sudden stratospheric warming. During this negative NAO phase the weakened westerlies allow more cold air to build up over North America and Eurasia.  相似文献   

INTERPRETING THE LARGE LIMB ERUPTION OF JULY 9, 1982     

Jordan  Stuart  Garcia  Adriana  Bumba  Vaclav 《Solar physics》1997,173(2):359-376

A time series of K3 spectroheliograms taken at the Coimbra Observatory exhibits an erupting loop on the east limb on July 9, 1982 in active region NOAA 3804. The Goddard SMM Hard X-Ray Burst Spectrometer (HXRBS) observations taken during this period reveal a hard X-ray flare occurring just before the loop eruption is observed, and SMS-GOES soft X-ray observations reveal a strong long-duration event (LDE) following the impulsive phase of the flare. A Solwind coronagram exhibits a powerful coronal mass ejection (CME) associated with the erupting loop. H flare and prominence observations as well as centimeter and decimeter radio observations of the event are also reviewed. A large, north–south-oriented quiescent prominence reported within the upper part of the CME expansion region may play a role in the eruption as well. The spatial and temporal correlations among these observations are examined in the light of two different current models for prominence eruption and CME activation: (1) The CME is triggered by the observed hard X-ray impulsive flare. (2) The CME is not triggered by a flare, and the observed soft X-ray flare is an LDE due to reconnection within the CME bubble. It is concluded that this event is probably of a mixed type that combines characteristics of models (1) and (2). The July 9 event is then compared to three other energetic CME and flare eruptions associated with the same active-region complex, all occurring in the period July 9 through September 4, 1982. It is noted that these four energetic events coincide with the final evolutionary phase of a long-lasting active-region complex, which is discussed in a companion paper (Bumba, Garcia, and Jordan, 1997). The paper concludes by addressing the solar flare myth controversy in the light of this work.  相似文献   

Palaeomagnetic pole positions in the Pre-Cambrian and Palaeozoic periods investigated from Czechoslovak rocks     

Václav Bucha 《Studia Geophysica et Geodaetica》1961,5(3):269-273

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On the diffusion of the perturbing toroidal magnetic field from the core to the mantle     

Gustáv Siráň  Reviewer V. Bucha  Reviewer I. Cupal 《Studia Geophysica et Geodaetica》1972,16(1):100-102

Zusammenfassung Es werden die Wurzeln einer charakteristischen Gleichung für die Randbedingung der Diffusion des toroidalen magnetischen Störungsfeldes berechnet, das in dünner Schicht unterhalb der Grenze Kern — Mantel, als eine Folge von Störung der Winkelgeschwindigkeit dieser Schicht in Anwesenheit des magnetischen Dipolfeldes induziert wird. Die Wurzeln werden für verschiedene Werte des Verhältnisses der Leitfähigkeit des Erdmantels und Erdkerns ausgerechnet. Es wird gezeigt, dass das aus dem Milieu mit der elektrischen Leitfähigkeit in das Milieu mit elektrischer Leitfähigkeit _m diffundierende toroidale magnetische Störungsfeld vom Werte _m/<10^–2 an von dem Verhältnis elektrischer Leitfähigkeiten beider Milieus unabhänging bleibt.  相似文献   

Integrating GRASS GIS and Jupyter Notebooks to facilitate advanced geospatial modeling education     

Caitlin Haedrich  Vaclav Petras  Anna Petrasova  Stefan Blumentrath  Helena Mitasova 《Transactions in GIS》2023,27(3):686-702

Open education materials are critical for the advancement of open science and the development of open-source software. These accessible and transparent materials provide an important pathway for sharing both standard geospatial analysis workflows and advanced research methods. Computational notebooks allow users to share live code with in-line visualizations and narrative text, making them a powerful interactive teaching tool for geospatial analytics. Specifically, Jupyter Notebooks are quickly becoming a standard format in open education. In this article, we introduce a new GRASS GIS package, grass.jupyter , that enhances the existing GRASS Python API to allow Jupyter Notebook users to easily manage and visualize GRASS data including spatiotemporal datasets. While there are many Python-based geospatial libraries available for use in Jupyter Notebooks, GRASS GIS has extensive geospatial functionality including support for multi-temporal analysis and dynamic simulations, making it a powerful teaching tool for advanced geospatial analytics. We discuss the development of grass.jupyter and demonstrate how the package facilitates teaching open-source geospatial modeling with a collection of Jupyter Notebooks designed for a graduate-level geospatial modeling course. The open education notebooks feature spatiotemporal data visualizations, hydrologic modeling, and spread simulations such as the spread of invasive species and urban growth.  相似文献   

Kirchhoff prestack depth migration in 3-D simple models: comparison of triclinic anisotropy with simpler anisotropies     

Václav Bucha 《Studia Geophysica et Geodaetica》2012,56(2):533-552

We use Kirchhoff prestack depth migration to calculate migrated sections in 3-D simple anisotropic homogeneous velocity models in order to demonstrate the impact of anisotropy on migrated images. The recorded wave field is generated in models composed of two homogeneous layers separated by one either non-inclined or inclined curved interface. The anisotropy in the upper layer is triclinic. We apply Kirchhoff prestack depth migration to velocity models with different types of anisotropy: a triclinic anisotropic medium, an isotropic medium, transversely isotropic media with a horizontal (HTI) and vertical (VTI) symmetry axis. We observe asymmetry in migration caused by triclinic anisotropy and we show the errors of the migrated interface caused by inaccurate velocity models used for migration. The study is limited to P-waves.  相似文献