Long term variation in the secular love number

Summary It has been demonstrated that the observed decrease in the second zonal geopotential harmonic linear in time and the secular decrease in the angular velocity of the Earth's rotation do not satisfy the relation defining the secular Love number k as constant during the whole history of the Earth's evolution. The discrepancy disappears if it is assumed thatdk/dt=–2.4×10^–6 cy^–1 .

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aa, m a ¶rt;a au m aauunmuaa u u a ¶rt;a u mu au u ¶rt;mm mu, n¶rt; u a a nm mu umuu u. a uam, u ¶rt;nmumdk/dt=–2,4·10 ^–6 (mmu)^–1 .

     

Global geoidal undulations as inferred from the Bruns formula and from inversion of the geopotential series

Summary The problem of inverting the geopotential series with respect to the geoid radius has been solved. A linearization of the radius powers, making use of a reference surface, has been applied. The body given by the Bruns' formula has been chosen as the reference surface. Corrections to the Bruns' formula in an analytical explicit form have been derived. An internal linearization accuracy of the order of 1 mm has been achieved. The geoid radius coefficients for the GEM-L2 model have been evaluated numerically. The corrections have been found to range from –90 to 90 cm.

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m¶rt; uauauu ¶rt; aaumuu u ¶rt; ama a¶rt;ua — ma, m una uum au aumau n u u naam unu¶rt;a. u u¶rt; una um uum u nmuaa u uum au a¶rt;ua — ma. ¶rt;a¶rt;amua ua, aa uauau, n¶rt;a 1 . u¶rt; u am ¶rt; ¶rt;uaumau n GEM-L2. au na nm mm m am nu annuauuu¶rt;a, a a m a, n¶rt;a ± 90 .

     

On one application of Ertel's theorem

u nu m¶rt;a a u u¶rt;a u u m ma, m mam uauu ¶rt; nm u. aa ¶rt; na nuam m umu uu u a¶rt;u uu m.     

Typical properties of dynamic systems and the instability of hydrodynamic flows

Summary Based on Peixot's theorem of topological dynamics, the unstable behaviour of hydrodynamic flows on a two-dimensional annuloid T ² is analysed. The generating property is the curvature of the group of S ₀ Diff T ² diffeomorphisms of the (Riemannian) flow region T ² . This group is the configuration space of the ideal fluid flowing on T ² .

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a m ma u mn u ¶rt;uauu ¶rt;am mu n¶rt;uu¶rt;¶rt;uauu nm a ¶rt; m T ² u¶rt; mu. ¶rt;au m m a m uuann S ₀ Diff T ² ¶rt;uu amu mu ( uaa) T ² . manna m uau nmam ¶rt; u¶rt;a u¶rt;mu a T ² .

     

Spectrum of the geomagnetic field in central Europe

mam na n uu nmaaum n a mumuu ¶rt; n. ammu ama 27-¶rt;a auau uuauuu n amuaa 7 ¶rt;nu amu nu¶rt; 1960–68 . ¶rt;a m ¶rt; mum nma maa m nmaum n nu a amumu.     

Magnetic anisotropy of polycrystalline haematite induced by A D. C. magnetic field

Summary The changes in the anisotropy of initial susceptibility of haematite ores, induced by a D.C. magnetic field are studied. After applying stronger magnetic fields, the changes in the anisotropy parameters are considerable and depend on the manner in which the basal planes of the haematite grains are arranged in the samples. The experimental results are interpreted on the basis of the single-domain theory. The proposed simple model of induced anisotropy is based on the relation between the directional susceptibility of the sample and the preferred orientation of the magnetic moments of the grains in polycrystalline haematite.

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am uu aumnuu aa nuuumuamum ¶rt;, a nm aum n. nuu u aum n uu aumnuu aam u aum m na n¶rt;u nmamum aa. numa. ¶rt;a umnmua unau ¶rt;¶rt; muu. ¶rt;a nma ¶rt; a aumnuu aa a auumu u nuuumu m umauu aum m nuumauamum.

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Presented at the 5th Scientific Assembly of IAGA in Prague 1985.     

Czech hydrometeorological institute limited-area operational forecast model

Summary The CHMI LAOFM is used in the daily routine of the Central Forecasting Office of the Czech Hydrometeorological Institute and some special results are transmitted to the regional offices. The model works in the region of Europe and the North Atlantic, uses conservative finite difference schemes and two types of semi-implicit schemes that allow effective model structurization in terms of programming language. The basic philosophy of the model is described.

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¶rt; a zau mumuu unm zumzu umumm () ¶rt; z uz nza. m mam ¶rt;a zu nzam am amuu. z amam amu n u amu mamuz aa, un am , a a aa au. ama aum mu auau z n- , ma cam m nm a auuam mmauau nza. mam nuaa u u auauu.

     

On free nutation of the rotation vector of a rigid body

aam, m ¶rt;-mau ¶rt;uu a ma au am m¶rt; ma m unmuu m m. ¶rt;a, u a u unmuu annuuam, m am n una u 0,1 u a u ammuuu ¶rt;mau aa m m.     

On some effects connected with electromagnetic induction in a rotating earth

muu aamuam mauma u¶rt;u, aa uauu n aum n aa , ma n¶rt;mam ¶rt;¶rt; n¶rt;u a. aam, m mam mum au u u ¶rt;a n, a¶rt;am, m a , a¶rt;am n u amm ¶rt;au, ¶rt;a n ( aa um ¶rt;uam). a aamuam u m maua ¶rt;¶rt; aum n a au ¶rt;¶rt; n¶rt; aa. a am uu n S_q auau a m au u u n m mu, m na a, mum a¶rt;a au a¶rt;u mu au u.     

Palaeointensity of the geomagnetic field during upper cainozoic derived from palaeo-slags and porcellanites in north Bohemia

Summary Porcellanites and palaeo-slags from North Bohemia are natural materials which can be used to derive the palaeomagnetic directions and palaeointensity of the geomagnetic field active at the time of caustic alteration. The origin of these rocks, called erdbrands, was due to the caustic alteration of predominantly pelitic sediments as a result of underground fires conditioned by spontaneous ignition of coal seams. The caustic alteration occurred during the Upper Pliocene to the Quaternary. Three procedure based on the methods by Thellier and Nagata are presented in the paper. The newly developed apparatus MAVACS (Magnetic Vacuum Control System) was used for the thermal demagnetization of samples. A procedure based on multi-component analysis was also proposed and tested. Besides some methodic results, it was found that the geomagnetic field intensity varied during the respective period within the limits of 48%±4% to 154%±32% of the present geomagnetic field intensity.

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aum u na au a mumuu uu n¶rt;mam nu¶rt; amua, m n¶rt;¶rt;um ¶rt; ¶rt;u naaum anau u naumumuaum n, ¶rt;m amu uu. mu n¶rt;, aa ¶rt;a¶rt;, uu n¶rt; uu amu uu num num a¶rt; n¶rt; ¶rt;mu aau . amu uu u m nu¶rt; m nua ¶rt; mmu nu¶rt;a. am n¶rt; mu umnmau nua, n¶rt;¶rt;u ¶rt; ¶rt;u naumumu, nuau a m¶rt; u aama. a aamaa annaama MAVACS (Magnetic Vacuum Control System) a unaa ¶rt; mu aauuau ¶rt; amu aa. n¶rt; u n n¶rt;¶rt;, a a munm aau amuauu. nu m¶rt;uu au, ma ma, m umumaum n u¶rt; nu¶rt; a n¶rt;a 48%±4%-154%±32% au umumu aum n.

     

Source radiation pattern andPKP amplitudes from the Tonga region

Summary The relation of short period PKP1 and PKP2 amplitudes from deep earthquakes in the Tonga region observed at a seismological station in Central Europe, is compared with the theoretical relations computed for different source radiation parameters and depths. The Preliminary Earth Model was used in the computations. Qualitatively good agreement of observed and calculated values was found for the radiation pattern corresponding to the likely geometry of the Tonga subduction zone. The influence of the variation of some source and model parameters on the calculated PKP1 and PKP2 relation is discussed.

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¶rt;a au mu anum¶rt; mnu¶rt; PKP1 u PKP2 mu mu a, anua ¶rt; u mau ma n, mmmuu mmuuu uuau, aumau ¶rt; a naam ua umua uu aa. ama unaa ¶rt; PREM. a¶rt; u auma uu ¶rt;am am au ¶rt; a uu, mmm mmuu ¶rt;uu a a. ¶rt;am uu auau naam umu u ¶rt;u a uu am mu anum¶rt; PKP1 u PKP2.

     

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

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.     

High heat flow measured in Ostrava-Karviná coal basin

aamuam mam uu mn nma ma-au a. a¶rt; uua¶rt;uma mnam, uuma mnn¶rt;mu u mn nma m ¶rt;uamau au uu uma, n¶rt; m n¶rt; mn nm nu¶rt; a. 2. a u au Q=1,99 u 2,06×10^–6 /² am ¶rt;au mu n ua amu, ma mu (2,5×10^–6 a/² ) aum nam mm ¶rt;uana. um mm am na m¶rt;, ¶rt;¶rt; nu¶rt;m am mam.     

Theoretical wiese induction vectors for a three-dimensional prism in the vicinity of a vertical contact

Summary With the use of the method of boundary integral equations, a stationary approximation of the magnetotelluric field for a three-dimensional prism located in the vicinity of a vertical contact of two quarterspaces, whereby the applied electric field is oriented parallel with the vertical boundary, is solved. In combination with the solution for the perpendicular orientation of the exciting electric field, the theoretical Wiese induction vectors for three positions of the 3-D prism are calculated. It was shown that the centre of divergence of the Wiese vectors is displaced from the epicentre of the prism, namely, if the prism is close to the vertical boundary.

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nu m¶rt;a ¶rt;a u¶rt;a au n¶rt;maa mauaa annuau u nu¶rt; mam u¶rt; ama a¶rt;ummu¶rt; n ¶rt; nu, an uu mua¶rt; mama ¶rt; mmnmam. ¶rt;a mu n n¶rt;na¶rt;am ana naa mua ¶rt;au. uau aamua¶rt; a a aauua a nn¶rt;u ana¶rt; ¶rt;a¶rt; n ¶rt;aa m uum mmuu u¶rt;u m u ¶rt; m nu m nu. aa, m m a¶rt;u m u mum numa nu, ¶rt;¶rt;a nua nuaam mua ¶rt;au.

     

One thermal model of the young oceanic lithosphere: Direct problem

Summary The two-dimensional solution of the direct plate model of the oceanic lithosphere is computed for t ^1/2 dependences of its thickness using the multi-grid technique for the bilinear finite elements. If we assume the dependence of the lithospheric thickness on its age in the form h(t)=6·6t ^1/2 +7·5, then this model can roughly approximate the measured heat flow. In this model the horizontal conductive term is not negligible, the heat flow depends both on time and on the velocity of the sea-floor spreading which should be taken into account for the handling of heat flow measurements.

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¶rt; u ¶rt; n a¶rt;au ¶rt; mu ¶rt;u au um auum mu m t ^1/2 . um mua muu¶rt;a ¶rt; uu m. u n¶rt;num auum mu m u u¶rt; h(t)=6.6t ^1/2 +7.5, m ma ¶rt; nuuum annuum a¶rt;a mn nm. m ¶rt;u numa ma mnn¶rt;mu; mn nm auum m u u m mu auu au ¶rt;a u, ¶rt;am, nu am uu mn nma a¶rt; umam uu mu auu.

     

Analysis and optimization of wide-band force-balance seismometer responses

¶rt; aau n¶rt;am uu, umu,au mummu u ¶rt;uau ¶rt;uanaa mu um. am n a nmua amm aamumuu um ¶rt; au uu nuu. ¶rt;ma ummuu m¶rt; nmuau mu um a a¶rt;a an¶rt;u n n¶rt;am uu n nmu.     

Three-dimensional modelling convection in the earth's mantle: Influence of the core-mantle boundary

Summary Mass heterogeneities in the Earth's mantle are derived from the spherical expansions of the core-mantle boundary topography, the surface topography and the external gravity field. The obtained density distribution provides the body forces driving the convection in the mantle. Assuming Newtonian rheology, the convection is modelled by solving the Stokes problem in the region extending from the top of the D"-layer to the base of the lithosphere. The derived model of mantle motions favours the concept of whole-mantle convection; its pattern connects the shape of the core-mantle boundary with surface tectonics.

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¶rt; aauu nmmu amuu u. am u¶rt; ¶rt;a una uum au ¶rt; ¶rt;aumau¶rt; n, a nmu u u nmu ¶rt;au amu-¶rt; ¶rt; n uu u. u, mmmu n an¶rt;u nmmu, am u. am m uu n¶rt;u amu ¶rt; ¶rt;au D" u u ¶rt;au um nu n¶rt;nuu, m amua amuu a¶rt;am mau m u¶rt;mu. a ¶rt; ¶rt;uu aama m, m ¶rt;u u u¶rt;u nmu n¶rt;m amu u am ¶rt;au ¶rt; amu u ¶rt; nm mmu.

     

Regularization of downward heat flow continuation

Summary Some regularization approaches to downward heat flow continuation from the Earth's surface to the depth of interest are presented, provided the heat transfer is described by the homogeneous steady-state equation. The Fourier transform of horizontal coordinates is used and the relation between the regularization of the heat flow spectrum and the regularization of the heat flow in the spatial domain are discussed. The utilization of an a priori information about the subsurface heat flow is mentioned.

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¶rt; m zuau n¶rt;¶rt; n¶rt;u u nmz mnz nma n¶rt;nuu, m n mna nuam ¶rt;¶rt; maua au (au anaa). na naau zuma ¶rt;uam u ama ¶rt; zuau mnz nma u uau z nma. nma m nuu anu u n¶rt;nmz mnz nma.

     

Geomagnetism of the external flysch Czechoslovakian Carpathians and the possible causes of anomalous geophysical manifestations

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.     

Velocities of seismic waves propagating through the Bohemian massif from foci in Poland

mam mm ua a na Pn, Pg, Sn u Sg nu¶rt;u u au -ma. aa, m ¶rt; amu 5° m numa ua¶rt;a ¶rt;am mu a na n au ma¶rt;amu u mu anmau , uu m n u ma¶rt;am¶rt;a. am nmau a uu m anmau mmu aua.