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371.
Cosmogenic nuclides in the Košice meteorite: Experimental investigations and Monte Carlo simulations 下载免费PDF全文
Pavel P. Povinec Jozef Masarik Ivan Sýkora Andrej Kováčik Juraj Beňo Matthias M. M. Meier Rainer Wieler Matthias Laubenstein Vladimir Porubčan 《Meteoritics & planetary science》2015,50(5):880-892
Results of nondestructive gamma‐ray analyses of cosmogenic radionuclides (7Be, 22Na, 26Al, 46Sc, 48V, 54Mn, 56Co, 57Co, 58Co, and 60Co) in 19 fragments of the Ko?ice meteorite are presented and discussed. The activities varied mainly with position of fragments in the meteoroid body, and with fluxes of cosmic‐ray particles in the space affecting radionuclides with different half‐lives. Monte Carlo simulations of the production rates of 60Co and 26Al compared with experimental data indicate that the pre‐atmospheric radius of the meteoroid was 50 ± 5 cm. In two Ko?ice fragments, He, Ne, and Ar concentrations and isotopic compositions were also analyzed. The noble‐gas cosmic‐ray exposure age of the Ko?ice meteorite is 5–7 Myr, consistent with the conspicuous peak (or doublet peak) in the exposure age histogram of H chondrites. One sample likely contains traces of implanted solar wind Ne, suggesting that Ko?ice is a regolith breccia. The agreement between the simulated and observed 26Al activities indicate that the meteoroid was mostly irradiated by a long‐term average flux of galactic cosmic rays of 4.8 particles cm?2 s?1, whereas the short‐lived radionuclide activities are more consistent with a flux of 7.0 protons cm?2 s?1 as a result of the low solar modulation of the galactic cosmic rays during the last few years before the meteorite fall. 相似文献
372.
Far-zone gravity field contributions corrected for the effect of topography by means of molodensky’s truncation coefficients 总被引:1,自引:0,他引:1
Robert Tenzer Pavel Novák Peter Vajda Artu Ellmann Ahmed Abdalla 《Studia Geophysica et Geodaetica》2011,55(1):55-71
A spectral representation of the topographic corrections to gravity field quantities is formulated in terms of spherical height
functions. When computing the far-zone contributions to the topographic corrections, various types of the truncation coefficients
are applied to a spectral representation of Newton’s integral. In this study we utilise Molodensky’s truncation coefficients
in deriving the expressions for the far-zone contributions to topographic corrections. The expressions for computing the far-zone
gravity field contributions corrected for the effect of topography are then obtained by combining the expressions for the
far-zone contributions to the gravity field quantities and to the respective topographic corrections, both expressed in terms
of Molodensky’s truncation coefficients. The numerical examples of the far-zone contributions to the topographic corrections
and to the topography-corrected gravity field quantities are given over the study area situated in the Canadian Rocky Mountains
with adjacent planes. Coefficients of the global elevation and geopotential models are used as the input data. 相似文献
373.
FFT-based high-performance spherical harmonic transformation 总被引:6,自引:0,他引:6
Spherical harmonic transformation is of practical interest in geodesy for transformation of globally distributed quantities such as gravity between space and frequency domains. The increasing spatial resolution of the latest and forthcoming gravitational models pose true computational challenges for classical algorithms since serious numerical instabilities arise during the computation of the respective base functions of the spherical harmonic expansion. A possible solution is the evaluation of the associated Legendre functions in the Fourier domain where numerical instabilities can be circumvented by an independent frequency-wise scaling of numerical coefficients into a numerically suitable double precision range. It is then rather straightforward to commit global fast data transformation into the Fourier domain and to evaluate subsequently spherical harmonic coefficients. For the inverse, the computation of respective Fourier coefficients from a given spherical harmonic model is performed as an inverse Fast Fourier Transform into globally distributed data points. The two-step formulation turns out to be stable even for very high resolutions as well as efficient when using state-of-the-art shared memory/multi-core architectures. In principle, any functional of the geopotential can be computed in this way. To give an example for the overall performance of the algorithm, we transformed an equiangular 1 arcmin grid of terrain elevation data corresponding to spherical harmonic degree and order 10800. 相似文献
374.
Documenting and detecting long-term precipitation trends: Where we are and what should be done 总被引:1,自引:0,他引:1
A brief review of problems and achievements in documenting precipitation changes during the period of instrumental measurements is presented. Concern is expressed that without appropriate studies in the coming period of a new generation of precipitation measurements, technological progress in instrumentation may adversely and inadvertently affect our capability for monitoring and detecting future changes in terrestrial precipitation. At the same time, only a new generation of instrumentation will be capable of resolving the problems of monitoring precipitation over oceans.Special attention is paid to validation of the increasing trend in terrestrial precipitation observed during the past hundred years at high latitudes of the northern hemisphere - a feature of global warming predicted by most climate models. 相似文献
375.
Jaroslava Bošková František Jiříček Pavel Tříska B. V. Lundin D. R. Shklyar Reviewer M. Hvoždara 《Studia Geophysica et Geodaetica》1988,32(2):199-212
Summary In a number of VLF experiments with low-orbiting Intercosmos satellites, high-intensity, discrete VLF emissions at frequencies above the local LHR were observed predominantly between L=2.3 and 4.0. The frequency of their intensity maximum varies continuously with geomagnetic latitude, and approximately parallels the value of a quarter of the equatorial electron gyrofrequency. An attempt is made to interprete these emissions in terms of quasi-electrostatic whistler-mode waves, generated in the near-equatorial region and propagating downward in the quasi-resonance mode. The generating mechanism is supposed to be the kinetic instability connected with the loss-cone and temperature anisotropy of the distribution function of energetic electrons. Some features of the discrete plasmaspheric emissions are discussed on the basis of theoretical considerations.
¶rt; num a umu nmua m a¶rt;au umu ¶rt;um -uu a amma, a amm , num ¶rt; L=2,3 u L=4. amma aua umumu mu uu um uuaum um u nuuum aa mmu amuauamm m. ¶rt;numa nnma umnmuam mu uu mua aummamuu um , ¶rt;a nuamua amu u anmau u au-a u. ¶rt;naam, m mu uu ¶rt;am mam umu mumu an¶rt;u u m, aumnu mnam u nm u uu an¶rt;u. n mmu aau ¶rt;am m mu ¶rt;umm na uu.相似文献
376.
Brázdil Rudolf Stucki Peter Szabó Péter Dobrovolný Petr Řezníčková Ladislava Kotyza Oldřich Valášek Hubert Dolák Lukáš Zahradníček Pavel Suchánková Silvie 《Theoretical and Applied Climatology》2018,132(3-4):1201-1216
Theoretical and Applied Climatology - One of the most disastrous windstorms to take place over the Czech Lands occurred on the night of 26/27 October 1870. It is here analysed through the use of... 相似文献
377.
Lucian?Sf?c?Email authorView authors OrcID profile Pavel?Ichim Liviu?Apostol Adrian?Ursu 《Theoretical and Applied Climatology》2018,134(3-4):777-791
The study underlines the characteristics of the urban heat island of Ia?i (Ia?i’s UHI) on the basis of 3 years of air temperature measurements obtained by fixed-point observations. We focus on the identification of UHI development and intensity as it is expressed by the temperature differences between the city centre and the rural surroundings. Annual, seasonal and daily characteristics of Ia?i’s UHI are investigated at the level of the classical weather observation. In brief, an intensity of 0.8 °C of UHI and a spatial extension which corresponds to the densely built area of the city were delineated. The Ia?i UHI is stronger during summer calm nights—when the inner city is warmer with 2.5–3 °C than the surroundings—and is weaker during windy spring days. The specific features of Ia?i’s UHI bear a profound connection to the specificity of the urban structure, the high atmospheric stability in the region and the local topography. Also, the effects of Ia?i’s UHI upon some environmental aspects are presented as study cases. For instance, under the direct influence of UHI, we have observed that in the city centre, the apricot tree blossoms earlier (with up to 4 days) and the depth of the snow cover is significantly lower (with up to 10 cm for a rural snow depth of 30 cm) than in the surrounding areas. 相似文献
378.
A spatiospectral localization method is discussed for processing the global geopotential coefficients from satellite mission
data to investigate time-variable gravity. The time-variable mass variation signal usually appears associated with a particular
geographical area yielding inherently regional structure, while the dependence of the satellite gravity errors on a geographical
region is not so evident. The proposed localization amplifies the signal-to-noise ratio of the (non-stationary) time-variable
signals in the geopotential coefficient estimates by localizing the global coefficients to the area where the signal is expected
to be largest. The results based on localization of the global satellite gravity coefficients such as Gravity Recovery And
Climate Experiment (GRACE) and Gravity and Ocean Circulation Explorer (GOCE) indicate that the coseismic deformation caused
by great earthquakes such as the 2004 Sumatra–Andaman earthquake can be detected by the low-low tracking and the gradiometer
data within the bandwidths of spherical degrees 15–30 and 25–100, respectively. However, the detection of terrestrial water
storage variation by GOCE gradiometer is equivocal even after localization. 相似文献
379.
Chris Zevenbergen Sebastiaan van Herk Jeroen Rijke Pavel Kabat Pieter Bloemen Richard Ashley Andrew Speers Berry Gersonius William Veerbeek 《Natural Hazards》2013,65(3):1217-1225
There is a growing international recognition that flood risk management in optima forma should be a programmed and flexible process of continuously improving management practices by active learning about the outcome of earlier and ongoing interventions and drivers of change. In the Netherlands, such a long-term, adaptive flood risk management strategy is now being implemented. This so-called second Delta Programme aims to identify and exploit opportunities and capitalize on short-term benefits and opportunistic synergies that arise from change and will require adaptive policymaking. It also requires the financial and institutional means to operate in a long-lasting way, which at the very least, means engaging stakeholders, gathering and disseminating results and adaptation of future plans. Transferring the Dutch approach to other countries is a major challenge that calls for fundamental changes in institutional arrangements at various levels and thus requires customized programmes for strategic institutional change. Recent examples of transfer will provide important lessons of how institutional change can successfully occur and will contribute insights for other countries that attempting to reform their flood risk management strategies. Continuous monitoring and evaluation and sharing international experiences will become crucial for the effective delivery and wider uptake of these new strategies around the globe. 相似文献
380.
This study presents the first preliminary U–Pb zircon data on tin-bearing S-type granites from the Gemeric unit of the Western Carpathians (Slovakia). U–Pb single zircon dating controlled by cathodoluminescence suggests crystallization of the Gemeric granites during Permian to Early Triassic (303–241 Ma) time. Post-crystallization, low-temperature metamorphic overprint is reflected by partial Pb loss in zircons. These Gemeric granites are younger than the highly fractionated, S-type, tin- and rare-element-bearing leucogranites in the European Variscides. They may have resulted from partial melting, triggered by increased heat flow from the mantle below the continental crust, and most probably intruded during the post-collisional extension and initial rifting of the Variscan orogenic belt. During Alpine orogeny, the Gemeric granites were affected by a low-temperature deformation and metamorphism. 相似文献