Global geoid sections determined by satellite orbit dynamics

Summary This paper ties up with [5, 6] the fundamental notations of which have been adopted. The sets of Stokes' constants (harmonic coefficients) J _n ^(k) , S _n ^(k) were adopted from [4], and the scale factor for lengths, R₀=GM/W₀, from [5]. The equations for global meridional and parallel sections of the geoid surface W=W₀ are formulated. The geoid sections are represented by best fitting ellipses, as regards the meridians always for the arcs between the equator and the pole. Address: Politickych vězňů 12, Praha 1-Nové Město.     

Determination of the original shape of pulsations from their spectra

Zusammenfassung Es wird eine einfache auf der Symmetrie der Grundformeln der Fourierschen Transformation gegründete Methode, wie von den Spektralfunktionen zur ursprünglichen Pulsationsform zu gelangen, beschrieben. Mit dieser Methode wird die durchschnittliche Form der Pi2-Pulsationen konstruiert. Diese idealisierte Pulsation hat dieselben Eigenschaften wie ein statistisches Ensemble von Pulsationen. Der wirkliche Verlauf der Intensit?t des magnetischen Feldes bei Pi2-Pulsationen wird durch die Methode aus den Induktionsregistrierungen abgeleitet. Die berechnete Kurve zeigt starke Korrelation mit der direkten Registrierung der Intensit?t des magnetischen Feldes.

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Address: Boční II, Praha 4-Spořilov.     

Chemical composition and physical properties of lithium-iron micas from the Krušné hory Mts. (Erzgebirge)

Compositions of natural lithium-iron micas are approximated best by the sidero-phyllite-polylithionite join. These micas contain little or no magnesium and manganese. Their octahedral sheets contain close to two trivalent cations (mainly aluminum) in small crystallographic sites and a variable quantity of lithium and R⁺² (mainly iron) in large sites. Octahedral vacancies are situated mostly in large sites. Lithium and R⁺² approach a 44 replacement relationship in micas with octahedral occupancy close to six. Lithium and fluorine show a good positive correlation (small excess of fluorine over lithium), which indicates a crystallochemical association between them. There is a less distinct positive correlation between lithium and R⁺⁴.Based on simplifications, a calculation shows that about two-thirds of octahedral vacancies are caused by substitutions within the octahedral sheet, one-third, by tetrahedral substitutions. Different methods of calculating the crystallochemical formula yield slightly different numbers of octahedral vacancies, but do not affect the mica's position in plots of physical parameters against composition. If a crystallochemical formula is calculated from analysis of a mica contaminated with quartz, topaz, or feldspar, the apparent number of octahedral vacancies increases; such a formula exhibits unusual behavior in composition plots.     

Core waves recorded in central Europe

Summary The core waves recorded at four seismograph stations in Central Europe were investigated with the aim to find the most suitable set of travel-time curves and a fitting model of the core structure. Another travel-time curve was constructed by means of time differences between the core phases. The differences in the features of the travel-time curves were studied using records of shallow, intermediate and deep shocks from the same focal region (Tonga).     

The mean curvature of the external equipotential surface and the vertical gravity gradient as functions of stokes's constants

Summary The mean curvature of the equipotential surface and the vertical gradient of gravity are expressed in terms of a development into a series of spherical harmonics [1, 2, 4], neglecting terms of the order of 10^–8. The curvature anomalies have been computed using the satellite data [3]. The symbols used are the same as in [5].Dedicated to 90th Birthday of Professor Frantiek Fiala     

Precision A.C. bridge set for measuring magnetic susceptibility of rocks and its anisotropy

Summary A bridge set for measuring the magnetic susceptibility of rocks and its anisotropy is described. The classical transformer bridge has been supplemented with an auxiliary compensating arm for balancing the bridge without any mechanical infringement of the measuring coils. By employing this principle and the appropriate methods a sensitivityof 4 × 10 ^–8 SI units (3 × 10 ^–9 e.m.u./cm³) has been achieved for a sample of 8 cm³ in volume. In addition to its high sensitivity the device has a considerable accuracy, which makes it suitable for susceptibility anisotropy measurements even of samples with a very low susceptibility and only slight anisotropy. Well-reproducible results have been achieved for samples with a mean susceptibility of the order of10 ^–5 SI units with an anisotropy degree of only about 1.05.Institute of Applied Geophysics.     

Differences between Mean Sea Levels for the Pacific,Atlantic and Indian Oceans From Topex/Poseidon Altimetry

Geopotential values W of the mean equipotential surfaces representing the mean ocean topography were computed on the basis of four years (1993 - 1996) TOPEX/POSEIDON altimeter data: W = 62 636 854.10m ² s ^–2 for the Pacific (P), W = 62 636 858.20m ² s ^–2 for the Atlantic (A), W = 62 636 856.28m ²s^–2 for the Indian (I) Oceans. The corresponding mean separations between the ocean levels were obtained as follows: A – P = – 42 cm, I– P = – 22 cm, I – A = 20 cm, the rms errors came out at about 0.3 cm. No sea surface topography model was used in the solution.     

A two-stage time series model for monthly hydrological projections under climate change in the Lim River basin (southeast Europe)

ABSTRACT

Climate change projections of precipitation and temperature suggest that Serbia could be one of the most affected regions in southeastern Europe. To prepare adaptation measures, the impact of climate changes on water resources needs to be assessed. Pilot research is carried out for the Lim River basin, in southeastern Europe, to predict monthly flows under different climate scenarios. For estimation of future water availability, an alternative approach of developing a deterministic-stochastic time series model is chosen. The proposed two-stage time series model consists of several components: trend, long-term periodicity, seasonality and the stochastic component. The latter is based on a transfer function model with two input variables, precipitation and temperature, as climatic drivers. The Nash-Sutcliffe model efficiency for the observed period 1950–2012 is 0.829. The model is applied for the long-term hydrological prediction under the representative concentration pathway (RCP) emissions scenarios for the future time frame 2013–2070.