Determination of tidal torques independently of densities

Summary The components of the tidal torques along the axes of the inertia ellipsoid of a perfectly elastic Earth have been derived quite independently of the density distribution of masses within the Earth. It has been demonstrated that not only the sectorial, but also the tesseral terms in the tidal forming potential are responsible for the tidal deceleration of the Earth's rotation.

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am ¶rt; mau ma nuu u m u a um unu¶rt;a uuu u¶rt;a n u, auu m ¶rt;a an¶rt;uu nmm a. aa, m nuu a¶rt;u au u a m muau, u mau nuuu au nuua nmua.

     

Normal density earth models

Summary Models of the Earth's density, close to thePREM model, have been derived, they reproduce the external normal gravitational field of the Earth and its dynamic flattening, and are referred to as normal density models. The Earth's surface is approximated by an ellipsoid of the order of the flattening, or of its square. Of the group of normal models sgtisfying the solution of the inverse problem, the normal density modelHME2 is recommended. The spherically symmetric density modelPREM, which was corrected in the course of solving the inverse problem, thus creating the modifiedPREM-E2 model, was used as the a priori information.

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¶rt; ¶rt;u an¶rt;u nmmu uu ¶rt;uPREM (m. a. a ¶rt;u nmmu), aumau n m u¶rt;mu na¶rt;am auaumau n u. m u annuum am unu¶rt; au. uau amu a ¶rt; mam H==0.003 273 994. ma ¶rt; a ¶rt; ¶rt;m ¶rt;HME2. am anu u a ¶rt; nmmu a unaa ¶rt; a¶rt;ua umua ¶rt;PREM. ¶rt;aam ¶rt;uuau m ¶rt;u n¶rt; aauPREM-E2.

     

Fundamental geodetic parameters of the earth's figure and the structure of the earth's gravity field derived from satellite data

Summary Using the geocentric constant GM=398 601.3 × 10 ⁹ m ³s ^–2 , the known value of the angular velocity of the Earth's rotation , Stokes' constants J _n ^(k) and S _n ^(k) upto n=21 (zonal), n=16 (tesseral and sectorial) [2], the geocentric co-ordinates and heights above sea-level of SAO satellite stations [2], the following will be derived: the potential on the geoid W_o, the scale factor for lengths R_o=GM/W_o, the radius-vector of the surface W=W_o, the parameters of the best-fitting Earth tri-axial ellipsoid, and the components of the deflections of the vertical with respect to the geocentric rotational IAG ellipsoid (Lucerne 1967), as well as to the best-fitting geocentric tri-axial ellipsoid. Some of the differences in the structure of the gravity field over the Northern and Southern Hemispheres will be given, and the mean values of gravity over the equatorial zone, determined from the dynamics of satellite orbits, on the one hand, and from terrestrial gravity data, on the other, will be compared.Presented at the Fifteenth IUGG General Assembly, Moscow, July 30 — August 14, 1971.     

The effect of uniaxial elastic deformation on the remanent magnetization of basalts

Summary The effect of uniaxial elastic deformation on the remanent magnetization of some basalts, containing generalized titanomagnetities of different chemical composition, was studied. The irreversible changes of the saturated and natural remanent magnetizations were measured. With the deformed samples no permanent change of the spectrum of micro-coercive forces, or change in the magnitude of the specific saturated remanent magnetization were observed. The experimental results agree with the model of mutual interaction of structural defects with magnetic domatins [10] under the assumption of predominantly reversible changes of the dislocation structure of the sample due to elastic deformation.     

The differences in structure of the gravity field and the figure of the earth in the northern and southern hemispheres

Summary It was shown in [5] that the flattening of parallel sections of the geoid (ϕ=const.) differs in the northern and southern hemispheres. This leads up to the idea of studying further the size and shape of the Earth and the structure of the gravity field separately for the northern and for the southern hemispheres. In this paper attention is devoted especially to the mean values of the radius-vectors, to the best fitting ellipsoid parameters and to the mean values of gravity for the whole hemispheres, on the one hand, and for their ϕ=const. sections, on the other. The symbols used are the same as in [5,6]. Address: Politickych vězňů 12, Praha 1-Nové Město.     

On the determination of propagation paths of mid-latitude whistlers for purposes of estimating the magnetospheric electron density

Zusammenfassung Mit dem Ziel das Profil der magnetosph?rischen Elektronendichte auf Grund einj?hriger Beobachtungsreihe der Station Panská Ves zu bestimmen, wurden M?glichkeiten von Ermittlung des tats?chlichen Ausbreitungsweges von Whistlern untersucht, die in den mittleren Breiten w?hrend des Minimums der Sonnenaktivit?t beobachtet wurden. Da die beobachteten Whistler keine “nose frequency” aufweisen, gründete sich die Bestimmung des Ausbreitungsweges auf Messungen der Dispersion auf 10 und 4 kHz, ?hnlich wie bei der Extrapolationsmethode der “nose frequency” [4]. Die gewonnenen Resultate zeigen, dass es m?glich ist, die Ausbreitungswege einer grossen Anzahl von Ein-Sprung-Whistler mit genügender Genauigkeit zu bestimmen. Alle auf diese Weise ermittelten Ausbreitungswege fallen in den BreitenbereichФ ₀=38°−56°, was der bekannten Tatsache entspricht, dass man verwendbare Whistler-Komponenten bis zu einer Entfernung von 1000 km vom Endpunkt ihres Ausbreitungsweges beobachten kann. Die analysierten Whistler entsprechen den unter Voraussetzung einer konstanten Elektronendichte in der H?he der Basis der Magnetosph?re (700 km) berechneten theoretischen Modellen. Unter diesen Bedingungen zeigte es sich als m?glich, alle analysierten Whistler zur Bestimmung des Profils der magnetosph?rischen Elektronendichte zu gebrauchen. Trotz aller Vereinfachungen, die bei der Konstruierung von Modellen angewendet wurden, ist es also m?glich, vernünftige Werte der Elektronendichte für den Breitenbereich L=1,5–3 unter Anwendung von Whistler-Beobachtungen aus einer einzigen Station in mittleren Breiten zu gewinnen.

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Address: Bočni II, Praha 4-Spořilov.