Equatorial flattening and principal moments of inertia of the earth     

Milan Burša  Zdislav Šíma  Reviewer M. Pick 《Studia Geophysica et Geodaetica》1984,28(1):9-10

am mam ¶rt;a naam mmu u n a ¶rt;nmuaa u amua m uuu u, mmmu ¶rt;u au (2), (3).  相似文献   

Deflections of the vertical on the territory of Europe from satellite data     

Milan Burša  Zdislav Šíma  Reviewer M. Pick 《Studia Geophysica et Geodaetica》1982,26(3):308-312

amu n¶rt;ma u ma mum au n¶rt;¶rt; m unu¶rt;a, amu n u amu uu, u n nmu ¶rt;a [2]; ¶rt;am nu uum, n m uum ¶rt;um au mau u ma ¶rt; muu¶rt;a.  相似文献   

Laboratory investigations on fault plane induced tensile cracks     

Jan Kozák  Jan Šílený  Ludvík Waniek  Reviewer V. Červený 《Studia Geophysica et Geodaetica》1981,25(4):332-342

Summary Tensile cracks induced by stress concentration around a fault plane in physical models under uniaxial load were analyzed. The results characterizing the decisive role of the fault plane inclination to the the stress direction are presented. Two stages of tensile crack life were determined, i.e. the first, seismoactive stage, accompanied by seismic energy release and the second aseismic one characterized by low velocity of crack propagation. Results obtained seem to be relevant to a better understanding of the character and regime of actual seismoactive faults.  相似文献   

Anomalous behaviour of seismic waves at an interface between anisotropic media     

Jan Šílený  Reviewer V. Červený 《Studia Geophysica et Geodaetica》1981,25(2):152-159

Summary An account of possible anomalous effects in reflection and refraction of elastic waves at an interface between anisotropic media is presented. These effects are due to anisotropy and they cannot occur at an interface between isotropic media. The shape of the slowness surface (its local deviations from spherical symmetry) is the decisive factor for appearance of these effects. A numerical example of such anomalous behaviour of elastic waves at a free boundary of the crystal of spinel is presented.  相似文献   

Long-term variability of temperature and precipitation in the Czech Lands: an attribution analysis     

Jiří Mikšovský  Rudolf Brázdil  Petr Štĕpánek  Pavel Zahradníček  Petr Pišoft 《Climatic change》2014,125(2):253-264

Among the key problems associated with the study of climate variability and its evolution are identification of the factors responsible for observed changes and quantification of their effects. Here, correlation and regression analysis are employed to detect the imprints of selected natural forcings (solar and volcanic activity) and anthropogenic influences (amounts of greenhouse gases—GHGs—and atmospheric aerosols), as well as prominent climatic oscillations (Southern Oscillation—SO, North Atlantic Oscillation—NAO, Atlantic Multidecadal Oscillation—AMO) in the Czech annual and monthly temperature and precipitation series for the 1866–2010 period. We show that the long-term evolution of Czech temperature change is dominated by the influence of an increasing concentration of anthropogenic GHGs (explaining most of the observed warming), combined with substantially lower, and generally statistically insignificant, contributions from the sulphate aerosols (mild cooling) and variations in solar activity (mild warming), but with no distinct imprint from major volcanic eruptions. A significant portion of the observed short-term temperature variability can be linked to the influence of NAO. The contributions from SO and AMO are substantially weaker in magnitude. Aside from NAO, no major influence from the explanatory variables was found in the precipitation series. Nonlinear forms of regression were used to test for nonlinear interactions between the predictors and temperature/precipitation; the nonlinearities disclosed were, however, very weak, or not detectable at all. In addition to the outcomes of the attribution analysis for the Czech series, results for European and global land temperatures are also shown and discussed.  相似文献   

Mineral and chemical composition of the Jezersko meteorite—A new chondrite from Slovenia     

Miloš Miler  Bojan Ambrožič  Breda Mirtič  Mateja Gosar  Sašo Šturm  Matej Dolenec  Miha Jeršek 《Meteoritics & planetary science》2014,49(10):1875-1887

The Jezersko meteorite is a newly confirmed stony meteorite found in 1992 in the Karavanke mountains, Slovenia. The meteorite is moderately weathered (W2), indicating short terrestrial residence time. Chondrules in partially recrystallized matrix are clearly discernible but often fragmented and have mean diameter of 0.73 mm. The meteorite consists of homogeneous olivine (Fa_19.4) and low‐Ca pyroxenes (Fs_16.7Wo_1.2), of which 34% are monoclinic, and minor plagioclase (Ab₈₃An₁₁Or₆) and Ca‐pyroxene (Fs₆Wo_45.8). Troilite, kamacite, zoned taenite, tetrataenite, chromite, and metallic copper comprise about 16.5 vol% of the meteorite. Phosphates are represented by merrillite and minor chlorapatite. Undulatory extinction in some olivine grains and other shock indicators suggests weak shock metamorphism between stages S2 and S3. The bulk chemical composition generally corresponds to the mean H chondrite composition. Low siderophile element contents indicate the oxidized character of the Jezersko parent body. The temperatures recorded by two‐pyroxene, olivine‐chromite, and olivine‐orthopyroxene geothermometers are 854 °C, 737–787 °C, and 750 °C, respectively. Mg concentration profiles across orthopyroxenes and clinopyroxenes indicate relatively fast cooling at temperatures above 700 °C. A low cooling rate of 10 °C Myr^?1 was obtained from metallographic data. Considering physical, chemical, and mineralogical properties, meteorite Jezersko was classified as an H4 S2(3) ordinary chondrite.  相似文献   

Reanalysis-driven climate simulation over CORDEX North America domain using the Canadian Regional Climate Model, version 5: model performance evaluation   总被引：1，自引：0，他引：1  

A. Martynov  R. Laprise  L. Sushama  K. Winger  L. Šeparović  B. Dugas 《Climate Dynamics》2013,41(11-12):2973-3005

The performance of reanalysis-driven Canadian Regional Climate Model, version 5 (CRCM5) in reproducing the present climate over the North American COordinated Regional climate Downscaling EXperiment domain for the 1989–2008 period has been assessed in comparison with several observation-based datasets. The model reproduces satisfactorily the near-surface temperature and precipitation characteristics over most part of North America. Coastal and mountainous zones remain problematic: a cold bias (2–6 °C) prevails over Rocky Mountains in summertime and all year-round over Mexico; winter precipitation in mountainous coastal regions is overestimated. The precipitation patterns related to the North American Monsoon are well reproduced, except on its northern limit. The spatial and temporal structure of the Great Plains Low-Level Jet is well reproduced by the model; however, the night-time precipitation maximum in the jet area is underestimated. The performance of CRCM5 was assessed against earlier CRCM versions and other RCMs. CRCM5 is shown to have been substantially improved compared to CRCM3 and CRCM4 in terms of seasonal mean statistics, and to be comparable to other modern RCMs.  相似文献   

Risk occurrences of damaging frosts during the growing season of vegetables in the Elbe River lowland,the Czech Republic     

Vera Potop  Pavel Zahraniček  Luboš Türkott  Petr Štěpánek  Josef Soukup 《Natural Hazards》2014,71(1):1-19

This study has, for the first time, analysed in detail the risk occurrences of the last spring frost, first fall frost and the length of the frost-free period during the growing season of vegetable crops at a high horizontal resolution of 10 km in the Elbe River lowland in the Czech Republic. The daily minimum air temperature from 116 grid points throughout the studied area for the period 1961–2011 was used. The daily values of minimum air temperature ranges of 0 to ?1.1 °C, ?1.2 to ?2.2 °C and below ?2.2 °C were considered to constitute mild, moderate and severe frost intensities, respectively. Firstly, the spatiotemporal variability of the date of the last spring frost, the date of the first fall frost and the length of the frost-free period in the Elbe River lowland is provided. Secondly, the estimation of the probability of a later date in the spring and an earlier date in the fall for various severe frost events and the length of the frost-free period is determined. Third, the changes in the timing of the last and first frosts of the three severities, as well as the length of the frost-free period, are evaluated. From 1961 to 2011, the Elbe River lowland has experienced a decrease in the number of frost days, while the length of the frost-free period between the last spring frost and the first fall frost has increased. The temporal evolution of the frost-free period anomalies displays two distinct periods: a shortening of the frost-free period in the 1960s and an intensified lengthening of the frost-free period since the 1980s. Whereas the latest spring frost has ended on an earlier date across the Elbe River lowland, the first frost date in the fall has generally been delayed to a later date. The dates of the last spring frost have advanced by ?0.21 days per year on average. The fall dates are delayed up to 0.18 days per year, whereas the frost-free period is lengthening by up to 0.39 days per year on average. However, regional frost series suggests that the frost-free period exhibits a large amount of inter-annual variability. In terms of the growth of field vegetables, a late spring frost remains a risk factor, but the degree of risk has decreased. There is a 25 % chance of the occurrence of dangerous spring frosts during the planting of field vegetables after 3rd May, but after 15th May, the risk is only 10 %.  相似文献   

The Little Ice Age signature and subsequent warming seen in borehole temperature logs versus solar forcing model     

Jacek Majorowicz  Jan Šafanda  Rajmund Przybylak 《International Journal of Earth Sciences》2014,103(4):1163-1173

The ‘low’ in the transient temperature versus depth borehole profiles around 120 m seen from deep temperature logs in the Canadian Prairies (southern Alberta–southern Saskatchewan), as well as in some of the European data, has been interpreted to be related to the Little Ice Age (LIA). Data point to the lowest ground surface and subsurface temperatures occurring in the very late eighteenth to nineteenth centuries. Inversion of these logs shows that surface temperature lows were followed by a recent warming period. Further, the synthetic profiles built on the basis of solar forcing history, stretching as far back as the beginning of the seventeenth century, suggest that the LIA signatures interpreted from the inversion of the borehole temperature logs would be difficult to be explained by known published models of past solar irradiation despite large range of assumed sensitivities for the couplings assumed, and that further forcing needs to be considered.  相似文献   

Isotope geochemistry and modelling of the multi-aquifer system in the eastern part of Lithuania     

Robert Mokrik  Vytautas Juodkazis  Anicetas Štuopis  Jonas Mažeika 《Hydrogeology Journal》2014,22(4):925-941

A steady-state groundwater flow model of three Quaternary intertill aquifers in the eastern part of Lithuania has been compiled. The distinction of separate modelled layers is based on hydraulic and isotope-hydrochemistry data criteria. ³H data were used to estimate the corrected groundwater age and were coupled with a groundwater-flow-dynamics model of the Quaternary aquifer system along a cross-section flow pathway from the Baltic Upland recharge area in eastern Lithuania towards the discharge area in the lowlands near the city of Kaunas in central Lithuania. The bicarbonate content in groundwater (214–462 mg/l) increases downgradient towards the lowland area. The other major constituents and total dissolved solids (TDS) have a trend analogous to the bicarbonate. The ¹⁴C activity of dissolved inorganic carbon (DIC) in the groundwater ranges from 41.4 to 85.7 pMC. With aquifer-system depth, active precipitation of aqueous solution takes place by dissolving minerals of calcite and dolomite and leakage of “old” groundwater from lower aquifers; the process is also traced by lower ¹⁴C and ³H activities and by more positive δ¹⁸O values in lowland areas.  相似文献