ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 106 (1991), S. 0 
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Let the Earth's equatorial principal moments of inertia be A and B, where A 〈 B, and the corresponding principal axes be a and b. Explicit formulae are here derived for determining the orientation of a and b axes and the difference B – A using C22 and S22, the two gravitational harmonic coefficients of degree 2 and order 2. For the Earth, the a axis lies along the (14.93°W, 165.07°E) diameter, and the b axis lies perpendicular to it along the (75.07°E, 104.93°W) diameter. The difference B – A is 7.260 × 10−6MR2. These quantities for other planets are contrasted, and geophysical implications are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 127 (1996), S. 0 
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The period P and Q-value of the Chandler wobble are two fundamental functional of the Earth's internal physical properties and global geodynamics. We revisit the problem of the estimation of P and Q, using 10.8 yr of modern polar motion as well as contemporary atmospheric angular momentum (AAM) data. We make full use of the knowledge that AAM is a major broad-band excitation source for the polar motion. We devise two optimization criteria under the assumption that, after removal of coherent seasonal and long-period signals, the non-AAM excitation is uncorrelated with the AAM. The procedures lead to optimal estimates for P and Q. Our best estimates, judging from comprehensive sets of Monte Carlo simulations, are P= 433.7 ± 1.8 (1σ) days, Q=49 with a la range of (35, 100). In the process we also obtain (as a by-product) an estimate of roughly 0.8 for a ‘mixing ratio’ of the inverted-barometer (IB) effect in the AAM pressure term, indicating that the ocean behaves nearly as IB in polar motion excitation on temporal scales from months to years
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 381 (1996), S. 595-597 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The Moon and Sun raise tides in the oceans, the atmosphere and the solid Earth. All three, but primarily the oceans, dissipate some amount of the imparted tidal energy; an accurate accounting of the tidal energy balance has been a long-sought goal12. The problem is of some importance, not only ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of geodesy 71 (1997), S. 344-350 
    ISSN: 1432-1394
    Keywords: Key words. Tides ; Arctic Ocean tides ; Earth rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract. Oceanic tidal angular momentum (OTAM) is calculated for the four major tides of the Arctic Ocean, based on the tidal elevations and current velocities from a recent two-dimensional numerical hydrodynamic model. The presented OTAM tables are meant to be complementary to other modeling studies that use satellite altimetry (which cannot observe Arctic Ocean tides because of ice cover and limited satellite inclinations). Although the Arctic Ocean's influence on earth rotation is, as may be expected, relatively small, the rapid advancement of the subject now calls for such small contributions to be explicitly accounted for.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-1394
    Keywords: Key words: Wavelet transform – Edge effect – Length of day
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract.  The edge effect in the wavelet time–frequency spectrum of a time series is treated. The time series is first extended on both ends by applying a non-linear model, namely the leap-step time series analysis (LSTSA) model, prior to the wavelet transform. The results of a series of simulation experiments and an application to the observed length-of-day (LOD) series demonstrate that the edge effect is effectively reduced this way. Thus, the application of the LSTSA model improves the wavelet time–frequency spectrum, especially enhancing the ability to detect the low-frequency signals.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1573-0956
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The cause- or causes-of the excitation of the Chandler wobble is one of the most intriguing problems in geophysics. As a result of one of the most valuable examples of an international programme, the positions of the pole have been determined since the late 19th century with remarkable accuracy. These data have always been accepted as of great importance in the study of the atmosphere, oceans and solid Earth. Recently, new techniques have greatly improved the accuracy with which the polar motion can be determined. Interpretation of the older data was made much more difficult because of their errors-for example the interesting suggestion that earthquakes were a cause of the excitation (by D. E. Smylie and L. Manshinha) could not be tested because their effects, if any, were lost in the noise. With the great improvement in the data it is now possible to suppose that comparable advances will be made in the theoretical interpretation. A discussion meeting at the Royal Astronomical Society on 8 May, 1987 on this topic was held and the following gives a short survey of this topic, consisting of brief summaries given by the speakers. This review is therefore a collective one which it is hoped will make more widely known these great technical advances and to fundamental interest of the phenomena of thepolar motion.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2014-09-07
    Description: Relative to the gravitational potential energy of the Earth's monopole, the multipole energy has received far less attention. In this paper, we recapitulate the basic physics from first principles and derive the formulas for multipole energies in analogy to classical electrostatic theory. We focus on the zonal quadrupole energy associated with the Earth's oblateness, the dominant term in Earth's gravity field apart from the monopole. We find the gravitational energy E oblateness 10 –6 | E monopole | = +2.5 x 10 26 J. We examine the implications of E oblateness and its changes associated with long-term ‘secular’ decreases in the oblateness parameter J 2 . We find the rate of loss of E oblateness due to the Earth rounding induced by the present-day GIA is about –200 GW, an amount quite significant in the kinetic energy budget of the mantle heat engine that drives the plate tectonics that has been estimated to be ~1 TW. We also assert that the tidal braking and the global earthquake dislocations, both resulting in Earth rounding on long-term geological timescales, are accompanied with a secular decrease of E oblateness at nearly the same rate of several GW.
    Keywords: Geodynamics and Tectonics
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2015-04-04
    Description: We develop a new method referred to as the AR-z spectrum for detecting harmonic signals with exponential decay/growth contained in a noisy time-series by extending the autoregressive (AR) method of Chao & Gilbert. The method consists of (i) ‘blindly’ forcing one 2nd-order AR fit to the signal content in the frequency domain for any chosen frequency whether or not there is truly a signal; (ii) finding the corresponding AR (complex-conjugate pair of) poles in the complex z -domain; (iii) converting the pole locations into the corresponding complex frequencies of the harmonic signals via the Prony's relation and (iv) constructing the Lorentzian power spectrum in the z -domain, conceptually constituting the analytical continuation of the spectrum from the (real) frequency domain to the complex z -domain, where a true harmonic signal is manifested as a Lorentzian peak. The AR-z spectrum can be further enhanced by forming the product spectrum from multiple records as available. We apply the AR-z spectral method to detect and to estimate the complex frequencies of the Earth's normal-modes of free oscillation using superconducting gravimeter records after recent large earthquakes. Specifically we show examples of detection and precise estimation of the frequencies and Q values of the split singlets of the spheroidal modes 0 S 2 , 2 S 1 , 1 S 2 and 0 S 0 , and report the mode couplings manifested by the gravimeter recording of the toroidal modes 0 T 2 , 0 T 3 and 0 T 4 . The AR-z spectrum proves to be highly sensitive for harmonic signal of decaying sinusoids in comparison to the conventional Fourier-based spectrum, particularly when the signal in question is weak and where high spectral resolution is desired.
    Keywords: Seismology
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2013-01-11
    Description: A sequence of large earthquakes happened along the Longitudinal Valley in eastern Taiwan in 1951. The first three (and largest) earthquakes took place near the harbour city of Hualien at the northern tip of the valley during the first day, the second of which (‘Event II’) severely damaged the city. The epicentre of Event II had previously been allocated at some 15 km offshore, which would result in a vertical subsidence of the Hualien city according to model calculations for the supposed seismic source mechanism. However, the Hualien tide gauge record speaks the opposite—the site experienced a co-seismic uplift by 255 mm due to Event II. We conduct a series of numerical grid-search simulations and determine a most likely scenario for the earthquake sequence. We assert that Event II's hypocentre was actually on land (rather than offshore), right along the recognized active Milun Fault below the city of Hualien at a very shallow depth. This result advances our understanding of the spatio-temporal seismotectonic behaviour associated with these historical events, and is important towards the assessment of the potential seismic and tsunami hazards of the region.
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2014-12-23
    Description: We raise attention to the issue of consistency between the reference frame with respect to which the seismological model calculations of displacement are made on one hand, and that to which the geodetic measurements of crustal deformation refer (e.g. the ITRF) on the other. This issue is critical in principle if the seismologically calculated displacement (or gravity change) is to be compared or used in joint inversion with geodetic measurements. A necessary set of conditions to be satisfied by inertial frames is the conservations of linear and angular momentums: no net change in them can be induced by a seismic source indigenous to the Earth. We show that the momentums are embodied in the degree-1 terms of the vector spherical-harmonic expansion of the displacement field. Using three largest recent earthquakes as case examples we find that the algorithms of seismological dislocation modelling in the literature do not conserve the momentums. However, quantitatively this inconsistency amounts to two orders of magnitude smaller than the current precision in the definition of the ITRF, hence insignificant in practice. Some caveats are raised.
    Keywords: Seismology
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...