Paläomagnetische Komplexuntersuchungen an Eruptiv- und Sedimentgesteinen des Böhmischen Massivs     

Vaclav Bucha  Žofíe Pokorna  Friedrich Frölich  Heiner Vollstädt 《Pure and Applied Geophysics》1965,61(1):101-112

Summary Complex methods, used at Potsdam since 1960 [4, 5, 6]³), nowadays are successfully tried for paleomagnetic studies also. Results in this direction in the following are discussed in detail.  相似文献   

Reviews     

D. F. Merriam  Vaclav Nemec 《Mathematical Geosciences》1973,5(2):211-212

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Changes in geomagnetic activity and global temperature during the past 40 years     

Václav Bucha 《Studia Geophysica et Geodaetica》2012,56(4):1095-1107

The purpose of this study is to investigate the effect of geomagnetic activity (used as a measure of solar wind parameters) on the variability of large-scale climate patterns and on changes in the global temperature. We show that positive statistically significant correlations between global temperature and the distribution of surface temperature over Eurasia, the East and Equatorial Pacific and over the North Atlantic for the period 1966?C2009 correspond to large-scale climate patterns defined by climate indices. We found very similar positive correlations between geomagnetic activity and the distribution of surface temperature in the mentioned regions. As an effect of geomagnetic storms, energetic particles penetrate from the magnetosphere into the region of the stratospheric polar vortex. The increase of temperature and pressure can be observed over northern Canada. The vortex shifts towards Europe, rotates counter-clockwise and the wind blows from the polar region over Greenland southwards. It diverts the warm flow proceeding northward over the Atlantic, eastward along the deep Icelandic low extending as far as the Barents Sea and takes part in warming Eurasia. The strengthened zonal flow from Siberia cools the western Pacific with the impact on the warming of the equatorial and eastern Pacific when also a distinct 1976?C78 climate shift occurred. Processes in the Atlantic and Pacific play a significant role and a time delay (wind forcing over the previous 1?C4 yr) appears to be the most important for the relocation of the oceanic gyres. Results showing statistically significant relations between time series for geomagnetic activity, for the sum of climate indices and for the global temperature help to verify findings concerning the chain of processes from the magnetosphere to the troposphere.  相似文献   

Possible geomagnetic activity effects on weather     

J. Bochníček  P. Hejda  V. Bucha  J. Pýcha 《Annales Geophysicae》1999,17(7):925-932

Tropospheric temperature and pressure fields on the Northern Hemisphere in the winter periods 1952–1996 were investigated. Composite maps of those fields, created for the high and low geomagnetic activity and individual quasi-biennial oscillation (QBO), phases show clear differences not only between different levels of geomagnetic activity, but also between the two phases of QBO. Special attention was given to the behaviour of the lower troposphere in January and February 1982.  相似文献   

Solution to the spectral filter problem of residual terrain modelling (RTM)     

Moritz Rexer  Christian Hirt  Blažej Bucha  Simon Holmes 《Journal of Geodesy》2018,92(6):675-690

In physical geodesy, the residual terrain modelling (RTM) technique is frequently used for high-frequency gravity forward modelling. In the RTM technique, a detailed elevation model is high-pass-filtered in the topography domain, which is not equivalent to filtering in the gravity domain. This in-equivalence, denoted as spectral filter problem of the RTM technique, gives rise to two imperfections (errors). The first imperfection is unwanted low-frequency (LF) gravity signals, and the second imperfection is missing high-frequency (HF) signals in the forward-modelled RTM gravity signal. This paper presents new solutions to the RTM spectral filter problem. Our solutions are based on explicit modelling of the two imperfections via corrections. The HF correction is computed using spectral domain gravity forward modelling that delivers the HF gravity signal generated by the long-wavelength RTM reference topography. The LF correction is obtained from pre-computed global RTM gravity grids that are low-pass-filtered using surface or solid spherical harmonics. A numerical case study reveals maximum absolute signal strengths of \(\sim 44\) mGal (0.5 mGal RMS) for the HF correction and \(\sim 33\) mGal (0.6 mGal RMS) for the LF correction w.r.t. a degree-2160 reference topography within the data coverage of the SRTM topography model (\(56^{\circ }\hbox {S} \le \phi \le 60^{\circ }\hbox {N}\)). Application of the LF and HF corrections to pre-computed global gravity models (here the GGMplus gravity maps) demonstrates the efficiency of the new corrections over topographically rugged terrain. Over Switzerland, consideration of the HF and LF corrections reduced the RMS of the residuals between GGMplus and ground-truth gravity from 4.41 to 3.27 mGal, which translates into \(\sim 26\)% improvement. Over a second test area (Canada), our corrections reduced the RMS of the residuals between GGMplus and ground-truth gravity from 5.65 to 5.30 mGal (\(\sim 6\)% improvement). Particularly over Switzerland, geophysical signals (associated, e.g. with valley fillings) were found to stand out more clearly in the RTM-reduced gravity measurements when the HF and LF correction are taken into account. In summary, the new RTM filter corrections can be easily computed and applied to improve the spectral filter characteristics of the popular RTM approach. Benefits are expected, e.g. in the context of the development of future ultra-high-resolution global gravity models, smoothing of observed gravity data in mountainous terrain and geophysical interpretations of RTM-reduced gravity measurements.  相似文献   

The intensity of the geomagnetic field in the quaternary     

Václav Bucha  Josef Horáček  Jan Rybář 《Studia Geophysica et Geodaetica》1968,12(1):56-62

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Connections between geophysical and meteorological processes     

Václav Bucha  Reviewer V. Brůžek 《Studia Geophysica et Geodaetica》1979,23(1):55-67

Summary The purpose of this paper is to contribute to the elucidation of the individual phases of the proposed mechanism of solar-terrestrial relations and changes of wheather [1–3], to point out mutually associated consequential events directly, using observed geophysical and meteorological data and to give proof, using concrete examples, of the effects of corpuscular radiation on the increase of temperature in the region of the auroral oval and on marked changes in the atmospheric circulation in the Northern Hemisphere.  相似文献   

Palaeomagnetism and plate tectonics since the lower palaeozoic     

Václav Bucha  Reviewer M. Krs 《Studia Geophysica et Geodaetica》1975,19(1):42-60

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