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61.
In many geoscientific applications, one needs to recover the quantities of interest from indirect observations blurred by
colored noise. Such quantities often correspond to the values of bounded linear functionals acting on the solution of some
observation equation. For example, various quantities are derived from harmonic coefficients of the Earth’s gravity potential.
Each such coefficient is the value of the corresponding linear functional. The goal of this paper is to discuss new means
to use information about the noise covariance structure, which allows order-optimal estimation of the functionals of interest
and does not involve a covariance operator directly in the estimation process. It is done on the basis of a balancing principle
for the choice of the regularization parameter, which is new in geoscientific applications. A number of tests demonstrate
its applicability. In particular, we could find appropriate regularization parameters by knowing a small part of the gravitational
field on the Earth’s surface with high precision and reconstructing the rest globally by downward continuation from satellite
data. 相似文献
62.
Grigory I. Dolgikh Stanislav G. Dolgikh Sergei N. Kovalev Vladimir V. Ovcharenko Vladimir A. Chupin Vyacheslav A. Shvets Sergei V. Yakovenko 《Acta Geophysica》2007,55(4):607-618
The experimental data in the microseismic frequency range obtained using the seismo-acoustic-hydrophysical measurement complex
are analyzed. The emphasis is put on estimating the ratio between the energy of surface sea wind waves in the area of the
Japan Sea where the complex was located and the Earth’s crust microdeformations in this frequency range. The experimental
evaluate obtained allow us to estimate the energy re-distribution at the hydrosphere-lithosphere boundary. 相似文献
63.
Sergei A. Klioner 《Celestial Mechanics and Dynamical Astronomy》2000,77(3):215-238
Various Fourier expansions of the planetary disturbing function can be computed numerically with the use of numerical Fourier
analysis. The task to compute the most general five-dimensional Fourier expansion of disturbing function has become feasible
with typical server-class computers quite recently. In such an expansion two anomalies, two arguments of perihelions and two
longitudes of the node are independent angular variables, while two semi-major axes, two eccentricities and two inclinations
are fixed numerically. The semianalytical expansion of the disturbing function resulting from numerical Fourier analysis theoretically
converges for any values of the parameters except for those sets of parameters which allow the bodies to collide. Various
aspects of the numerical computation of the Fourier expansion are discussed. Theoretical and practical convergence of the
Fourier series is discussed and illustrated.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
64.
Abstract We analyzed the relationship between an index of Great Lakes winter severity (winters 1950–1998) and atmospheric circulation characteristics. Classification and Regression Tree analysis methods allowed us to develop a simple characterization of warm, normal and cold winters in terms of teleconnection indices and their combinations. Results are presented in the form of decision trees. The single most important classifier for warm winters was the Polar/Eurasian index (POL). A majority of warm winters (12 out of 15) occurred when this index was substantially positive (POL > 0.23). There were no cold winters when this condition was in place. Warm winters are associated with a positive phase of the Western Pacific pattern and El Niño events in the equatorial Pacific. The association between cold winters and La Niña events was much weaker. Thus, the effect of the El Niño/Southern Oscillation (ENSO) on severity of winters in the Great Lakes basin is not symmetric. The structure of the relationship between the index of winter severity and teleconnection indices is more complex for cold winters than for warm winters. It takes two or more indices to successfully classify cold winters. In general, warm winters are characterized by a predominantly zonal type of atmospheric circulation over the Northern Hemisphere (type W1). Within this type of circulation it is possible to distinguish two sub‐types, W2 and W3. Sub‐type W2 is characterized by a high‐pressure cell over North America, which is accompanied by enhanced cyclonic activity over the eastern North Pacific. Due to a broad southerly “anomalous” flow, surface air temperatures (SATs) are above normal almost everywhere over the continent. During the W3 sub‐type, the polar jet stream over North America, instead of forming a typical ridge‐trough pattern, is almost entirely zonal, thus effectively blocking an advection of cold Arctic air to the south. Cold winters tend to occur when the atmospheric circulation is more meridional (type C1). As with warm winters, there are two sub‐types of circulation, C2 and C3. In the case of C2, the jet stream loops southward over the western part of North America, but its northern excursion over the eastern part is suppressed. In this situation, the probability of a cold winter is higher for Lake Superior than for the lower Great Lakes. Sub‐type C3 is characterized by an amplification of the climatological ridge over the Rockies and the trough over the East Coast. The strongest negative SAT anomalies are located south of the Great Lakes basin, so that the probability of a cold winter is higher for the lower Great Lakes than for Lake Superior. 相似文献
65.
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68.
Konstantin V. Kholshevnikov Sergei L. Kurdubov 《Celestial Mechanics and Dynamical Astronomy》2004,89(1):83-96
According to the classical theory of equilibrium figures, surfaces of equal density, potential and pressure concur (let us
call them isobars). Isobars can be represented by means of Liapunov power series in small parameter q, up to the first approximation coinciding with the centrifugal to gravitational force ratio at the equator. Liapunov has
proved the existence of the universal convergence domain: the above mentioned series converge for all bodies (satisfying a natural condition that the density ρ decreases from the center to the surface) if |q| < q*. Using Liapunov’s algorithm and symbolic manipulation tools, we have found q*= 0.000370916. Evidently, the convergence radius q* may be much greater in common situations. To comfirm it it is reasonable to consider two limiting and one or two intermediate
cases for the density behaviour: ρ is a constant, the Dirac’s δ-function, linear function of the distance from the center,
etc. And indeed, in the previous paper we find a three orders of magnitude greater value for homogeneous figures. In the present
paper we find that in the opposite case of Huygens-Roche figures (a point-mass surrounded by a weightless atmosphere) the
convergence radius is unexpectedly large and coincides with the well-known biggest possible value q*= 0.541115598 for such a class of figures. To ascertain it we ought to use numerical calculations, so our main result is
demonstrated by means of a computer assisted proof.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
69.
SergeiPisarevsky 《东北亚地学研究》2004,7(1):8-14
With the latest information on geology, isotop chronology, geochemistry and aerial geophysics, the structural enviroment, geological event characterists and evolution history of component units of Rodinia Supercontinent on a global scale are discussed. And some neo views and genetic pattern are provided. The East Eurppean Craton had a complex evolution history between 1.7 and 0.9 Ga. The arthors propose a new reconstruction of Laurentia acient land and Siberia at ca. 1 050-1 000 Ma. The largest litho-structural record of the Meso-Neoproterozoic orogenic collage in South America made up the western border of the South American Platform African Cratons are the result of convergence of Paleoproterozoic/Archaem Cratonic blocks. A part of Eastern Antarctica attached to southern Africa in Mesoproterozoic.Neoproterozoic felsic magmatic events in New India made the western border of Rodinia Pre-Grevoillian Laurentia was established as a major continental block by the end of the Paleoproterozoic. South China is geologically plausible to be between southern Laurentia and eastern Australia. Yangzi-Tarim connection or neighborhood is proposed. According to the abovementionded, the assembly and breakup paattem of Rodinia proposed by Pisarevsky is tested. It telles that primary break up is along the western border of Laurentia ancient land, which is similar to northern Atlantic. Another characteristic is that some continents are not considered as component parts of Rodinia, eg. India, Congo and San-Francisco. 相似文献
70.