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1.
The results of a detailed numerical study of the behaviour of the convective polar ionosphere are presented. The developed theoretical model produces three-dimensional distribution of electron density, electron and ion temperature. The effects of auroral particle precipitation on the density and temperature structures are studied for winter and low solar activity conditions. The high-latitude ionospheric features, such as the tongue of ionization, the main trough the polar ionization peak, the auroral ionization peak, the high-latitude ionization hole, the tongue of electron temperature, the high latitude minima of electron, temperature, and the ion temperature hot spot are obtained from calculations.Numerically obtained results are used for determining the HF propagation paths in the polar ionosphere. The effects of ionospheric irregularities on high frequency ionospheric radio waves are investigated by using a three-dimensional ray-tracing computer program. Ray-path trajectories are presented for different values of the elevation angle of transmission. From our study, it was found that large-scale irregularity structures of the high-latitude ionosphere, in the presence of the earth's magnetic field, significantly affect high frequency radio wave propagation.  相似文献   

2.
Summary With a self-neutralizing, rocket-borne parachute aspiration probe concentration and mobility measurements of positively and negatively charged carriers were made between 72 and 40 km over Sardinia. Between 72 km and 60 km a heavy and a light group of positively charged particles were found. The heavy group was more abundant than the hight group in the greater heights. For the negatively charged particles only one mobility group was found which roughly corresponded to the mobility of the light group of the positively charged carriers. The probe was designed so that no electrons could enter the analyzer section of the aspiration system. By this the electron concentration was given by the difference in concentration between the positively and negatively charged particles.This paper was read byH. Dolezalek, in an abbreviated form supplied by the authors.  相似文献   

3.
a m m n¶rt; uua ¶rt; au anauu a nmu n¶rt;nuu, m u ¶rt;a a ¶rt;u -um, ma u amu um ¶rt;uam. a namu unm ¶rt;a anau, nu a¶rt;u m m aua n-a. nuam n¶rt; n¶rt;u au — D-nmuamu — naa uu anau ¶rt; n¶rt;u a.  相似文献   

4.
Summary Secular non-tidal variations of geopotential and gravity are estimated due to secular decrease of the second zonal geopotential harmonic, secular polar motion and deceleration of the Earth's rotation.
am a nuu uunmuaa u u u mmu, a u m aauunmuaa, ¶rt;uu n u u mu au u.
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5.
Recent investigations of magnetospheric plasma structure are summarized under the broad categories of empirical models, transport across boundaries, formation, and dynamics of the plasma sheet. This report reviews work in these areas during the period 1991 to 1993. Fully three-dimensional empirical models and simulations have become important contributors to our understanding of the magnetospheric system. Some new structural concepts have appeared in the literature: the entry boundary and geopause, the plasma sheet region 1 vortices, the low-energy layer, the adiabaticity boundary or wall region, and a region in the tail to which we refer as the injection port. Traditional structural concepts have also been the subject of recent study, notably the plasmapause, the magnetopause, and the plasma sheet. Significant progress has been made in understanding the nature of plasma sheet formation and dynamics, but the acceleration of electrons to high energy remains somewhat mysterious.  相似文献   

6.
Summary The vertical distribution of the contribution of the energy flux density due to the Alfvén(ordinary) wave, guided by the geomagnetic field(and propagating through the ionosphere to the Earth's surface) in the horizontal direction is demonstrated in the mechanism of the horizontal propagation of the Pc1 signal. The distribution with height is shown of the variations of the polarization characteristics of the propagating wave(e.g. the rotation of the polarization plane, changes in ellipticity, attenuation, etc.), which are the result of coupling in the denser layers of the low ionosphere in which also suitable isotropic(extraordinary) modes are generated. The results obtained using the method described in[4, 13] are demonstrated on a model of the daytime ionosphere under incidence of ordinaryL-modes, frequency f=0.3 Hz, and various meridional angles at the ionosphere.
auauma anmau uaa Pc1 naa m an¶rt;u ¶rt;u nmmu ma uu uma anauu maum n n¶rt; , anma u nmu. naa m an¶rt;u uu aamumu nuauu anma (nauau nmu nuauu, uu unmumu, amau u m.¶rt;.), m m ¶rt;mu au¶rt;mu na uu u . ¶rt; mum n¶rt;¶rt;u umn() ¶rt;. mam num m¶rt; [4, 13] ¶rt;mua ¶rt;u ¶rt; u nu na¶rt;uu a u L-¶rt; amm f=0,3 n¶rt; au u¶rt;uau au.
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7.
a mam 10-mu u¶rt;au ¶rt;uauu nmu a anam. auum aam mua ¶rt;uu u nu amu uu, a , muu, u auauu n u mmu u uu umaa u ¶rt; nmu uuau.  相似文献   

8.
Long-period recordings of dispersive Rayleigh waves along numerous station lines, or profiles, in Europe have for the first time permitted a uniform inversion of these observations based on a new method of phase velocity regionalization.Regional dispersion relations obtained by this method have then been subjected to a complete inversion procedure commonly known as the hedgehog method. The results are presented in a map outlining the thickness of the lower lithosphere (lid) and the shear (S) velocities in both the lid and the asthenosphere channel.A comparison of these results with the minimum compressional (P) wave velocities in the asthenosphere and their corresponding depths provides an estimate of theV p /V s ratio for the asthenosphere in the European area.Contribution No. 314, Institute of Geophysics, ETH-Zürich, Switzerland.  相似文献   

9.
Summary Simple linear representation of the components of an approximate plane solution of point mass loading of the Earth's surface in a conveniently chosen coordinate system leads to selection of a 2nd-degree curve which is the best fit of the spherical solution for the given Earth model. The new approximate solution, which, analogously to the plane solution, can be called a parabolic solution, enables the simple input parameters of the plane solution to be used also for substantially larger angular distances. The comparison with the spherical solution is carried out by computing the effects of the M2-wave of ocean tides. The results of the computations for the tidal station Brussels prove the two solutions to be in sufficient agreement for global problems as well.
m nu uau aa nuuum nm u m m au nmu u n¶rt;¶rt; um ¶rt;uam ¶rt;m ma u m mnu, ma auu a n¶rt;¶rt;um u u ¶rt; ¶rt;a ¶rt;u u. nuuum u, m n aauu nm u aam naauu u, nm unam nm ¶rt; ¶rt;a nm u ¶rt;a ¶rt; m u amu. au uu u m uu uu 2 u nuu. mam uu ¶rt; nuu mauu ¶rt;aam ¶rt;mum au u u ¶rt;a ¶rt;a a¶rt;a.
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10.
Throughout the last twenty years, 3D seismic ray modelling has developed from a research tool to a more operational tool that has gained growing interest in the petroleum industry. Various areas of application have been established and new ones are under development. Many of these applications require a modelling system with flexible, robust and efficient modelling algorithms in the core. The present paper reviews the basic elements of such a system, based on the open model concept and the wavefront construction technique. In the latter, ervený's dynamic ray tracing is an intrinsic part. The modelling system can be used for generating ray attributes and synthetic seismograms for realistic 3D surveys with tens of thousands of shots and receivers. Moreover, some other types of application areas are illustrated: Production of Green's functions for prestack depth migration and hybrid modelling (combined ray and finite-difference modelling), attribute mapping and illumination analysis, both for survey planning and interpretation. Finally, the concepts of isochron rays and velocity rays related to seismic isochrons have been introduced recently, with very interesting future applications.  相似文献   

11.
Summary A model, explaining the effect of air pressure changes in the space of the measuring system on the fine dial counter constant of the Worden and similar gravity meters, is presented. It is based on the changes of the bellows volume with compensating the gravity changes. It is shown that the resetting the gravity meter in the whole range has practically no influence on the fine dial counter constant.
u¶rt;a ¶rt;, na m uu ¶rt;au ¶rt;a nmam uum um a nm a umaauma ¶rt; u nuaum. ¶rt; aa a uu a ua umu uma nu nauu uu u mmu. aa, m nma ¶rt;uanaa um namuu um a uu nm a uma.
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12.
Summary Results on electrical conductivity, chemical analysis and age of the rock samples from the Indian Subcontinent are presented. The old Precambrian Indian rocks tend to be less conductive than characteristic rocks of crustal and upper mantle structures.
nuam mam uu mnm¶rt;mu, uu aaua u n¶rt;u u uu n¶rt; u ¶rt;uu. ma nauu n¶rt; u ¶rt;uu naam mn¶rt;m aamumuu n¶rt; u amuu.
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13.
uu mnam a anu nuuauma Gs 15 No 228 u a m mnam m nua a n u — . (5). au u n¶rt; a 5 u a ¶rt;mu annaam n aa uu mnam — a. 1. ¶rt;: uum mmamuauauma (1/191), mamuu mnam uum annaam (–5,24 –2/°C), mamuu mnam uum uum umauma (–1 –2/°C). m u anum¶rt; u a amm aamumuu u uu — a. 2, 3 u u. 6, 7. aua uu auau mnam a anuauma nu nu¶rt; 6 a — a n¶rt; mamu mnam uu.  相似文献   

14.
Summary Based on model considerations it is shown that, under certain assumptions, zonalization of tropospheric circulation may be expected in the region of the auroral oval as a result of heat released at the time energetic electrons penetrate from the Sun into the lower stratosphere.
a auu ¶rt; a¶rt;u naa, m nu m n¶rt;nu u¶rt;am auau mn uuu amu aa aa mam ¶rt;u mna nuu mumu m u a u mam.
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15.
The pirmary objective of this paper is to review inversion algorithms employed to interpret magnetotelluric data by the geophysical/electromagnetics group at Brown University. Examples are presented from a variety of tectonic regimes — the Rio Grande rift, the Colorado Plateau, and Iceland. Following a brief tutorial in which the basic relations for the inverse prrolem are developed, we discuss the detectability and resolvability of various elements of the models. The correlation between certain model parameters is stressed, a phenomena well-known to interpreters. In this paper we emphasize the importance of identifying the precise range of values for which two or more parameters are coupled — these ranges are defined by what wer term saturation limits. Generalized inverse theory is employed to arrive at optimal models which are evaluated in terms of resolution and information matrices. The degree to which models fit a given dat base can be assessed using several quantitative approaches. We have found that it is impotant not only to determine the best fitting model, but also to identify those marginal solutions which also fall within the range of uncertainty of the data. The results from our direct invverse method agree favorably with those from Monte Carlo methods.  相似文献   

16.
Summary A new version of the seismic zoning map of Czechoslovakia is presented mainly for use with the revised Building Code SN 730 036 (Seismic Loads on Buildings). In principle, the map contains the expected maximum intensities according to the macroseismic scale MSK-64. The map is based on all historical macroseismic observations in Czechoslovakia, as well as on models of macroseismic fields. The assessment of expected intensities has also been completed by a seismotectonic analysis. It is not feasible to relate the map to a particular time interval, i.e. to estimate the probability of expected maximum intensities, because of the unknown recurrence of extreme events on the territory of Czechoslovakia.
ma a ama u auau auu, n ¶rt; n¶rt;m ¶rt; m¶rt;u SN 730 036 aa nm uuu ¶rt;muu. ama ¶rt;um ¶rt;u u¶rt;a aua uua umumu n aMSK-64. ama aa a ¶rt; u n um auu a¶rt;u a mumuu auu u a ¶rt; auu n. a ¶rt;aa a u¶rt;a umumu m mmu aaua. ua nmm u mu a mumuu nm mmu am u auau n¶rt; uma, m. . n¶rt;um ¶rt;mam mm mm u¶rt;a aua uu umumu.
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17.
Summary The basic formula used in the presented paper gives the relation between the P wave travel-time perturbation and the perturbation of an inhomogeneous transversely isotropic medium, expressed by four perturbations of elastic parameters and by two angles of orientation of the axis of symmetry of transverse isotropy in space. The travel time perturbation is computed along the ray in the unperturbed inhomogeneous isotropic medium. Four elastic parameters and two angles are parametrized in the model under study and a system of equations for many rays is constructed. The equations are linear in the sought elastic parameters and nonlinear in the sought angles, and the iterative Levenberg-Marquardt algorithm is thus used to solve them. The theoretical 3-D inverse problem was solved in the presented numerical example. The data, simulating teleseismic data, were computed in the direct problem and then inverted. The results indicate the applicability and limitation of the presented algorithm in real problems.
a a, unaa n¶rt;aa am, ¶rt;am mu ¶rt; uu u na u uu ¶rt;¶rt; nn umn ¶rt;, a m nuu naamau u ¶rt; au umauu u umuu nn umnuu nmam. u u na um ¶rt; a aa ¶rt;¶rt; umn ¶rt;. nu naam u ¶rt;a a naamuua ¶rt;u u nma uma au ¶rt; u . au u n um nu naama u u n um a umauu umuu, nm un m umamu aum a-aa¶rt;ma ¶rt; u u. am nu¶rt; ¶rt; m u nu. nu muu ¶rt;a aaa a na a¶rt;aa u am ¶rt;a a. mam naam auu u mu nuu nu¶rt;uma a a.
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18.
a aam u¶rt;au m ua aum aauu nu¶rt;u ¶rt; u anam a ¶rt;mu uu mu amuma n nu aum nuuumu num a¶rt;a uu ma¶rt;uuma, a m um ¶rt;u n u-a nummu ¶rt;¶rt;. num naau, m mua n¶rt;um nu¶rt; u ma aamam. a n¶rt;a umnmau aauuu u a mumuu m auu,¶rt; umuu n aaumu u mu n¶rt;umu m uam au u a mam ¶rt;u n n¶rt;a.  相似文献   

19.
¶rt; aau ua au u¶rt;a, umu a nmu m-10 n uum mau mu n (). am au ¶rt;uana amm. aa ¶rt;¶rt;auma umnmau uuu u, auau nu ua au u¶rt;a.  相似文献   

20.
Lava-like tuffs are lithologically indistinguishable from lavas, and form part of a temperature-and composition-controlled continuum from low-grade tuffs (which are non-welded or slightly welded), through high-grade (densely welded) tuffs, extremely high-grade tuffs (which may be agglutinated right to their upper and lower contacts), to spatter-fed lava flows. In some high-grade tuffs, a component of nonparticulate flow may postdate emplacement and deposition, but in extremely high-grade tuffs non-particulate deformation normally occurs during emplacement and deposition. In such cases, syn-depositional non-particulate deformation (previously called primary welding) and non-particulate slumping (previously called secondary flowage) processes overlap and are continuous, one into the other, so that distinction between them and their resultant structures is unrealistic and inapplicable. Therefore the term rheomorphism should be used to embrace all types of non-particulate flow. The Bad Step Tuff is the most lava-like of a sequence of rheomorphic calc-alkaline rhyolitic ignimbrites emplaced during a climactic caldera-forming eruption episode in the English Lake District. It is a ponded sheet, 40 to 400 m thick, which comprises a basal crudely stratified heterolithic breccia, a thick flow-laminated and locally vesicular central part, which beomes increasingly flow-folded upwards, and an upper autobreccia. Despite an absence of vitroclastic textures within the main laminated part, field relations show it to be a tuff. Diagnostic criteria are (1) a gradation, within a lithophysal zone, from unambiguous vitroclastic matrix of the basal lithic breccia upwards into the central flow-laminated tuff; (2) only rate autobreccia at the base of the sheet but ubiquitous autobreccia at the top of the sheet; and (3) close textural similarity with localized, intensely rheomorphic parts of associated ignimbrites that widely display unequivocal vitroclastic textures where their rheomorphism is less marked. The extremely high-grade character of the Bad Step Tuff may reflect its proximal setting in a piecemeal-type caldera. High emplacement temperatures resulted from high-rate but low-velocity vent emission from fissures along numerous cross-cutting calderafloor faults, producing very low boil over eruption columns and proximal ponding.  相似文献   

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