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981.
The polar cusps of the magnetosphere are key regions for the transfer of mass, momentum, and energy from the solar wind into the magnetosphere. Understaning these key regions and the dynamical interactions that occur there are fundamentally important to determining the physical nature of the magnetosphere. In this paper we try to summarize many of the conclusions reached in the papers of this special issue emphasizing the present concepts and definition of the cusp, what variations could be temporal structures and what could be spatial structures. We address the need for further measurements and the role of present and planned projects to address these needs. 相似文献
982.
We study the mineralogical changes suffered by specimens of natural miocene red and green continental sandstones (from Pozuelos Formation and Tiomayo Formation) cropping out in the Argentine Puna that increase their bulk magnetic susceptibility and change color when thermally treated. We hypothesize that on heating siderite, which is present in small quantities as cement in the studied sandstones, would oxidize and decompose into maghemite and/or magnetite. Subsequent heating to higher temperatures sometimes would bring about the conversion of maghemite and/or magnetite to hematite. Mössbauer spectroscopy proved to be a very valuable tool for the determination of the presence of siderite in small amounts in the studied samples. The present results show that further work is needed in order to fully understand the mineralogical changes suffered by continental sandstones during heating. The characterization of such changes occurred during laboratory routines is relevant, since they can help to better understand natural processes. 相似文献
983.
J. Plomerova L. Vecsey V. Babuska M. Granet U. Achauer 《Studia Geophysica et Geodaetica》2005,49(4):541-560
We present results of an array study of seismic anisotropy beneath the Bohemian Massif (BM) showing distinct lateral and directional
variations of the fast shear-wave polarization and split-delay time consistent with variations in the P-residual spheres,
in which directional means of relative residuals are subtracted. Our analysis of the S- and P-wave anisotropy suggests that
the mantle lithosphere of the BM consists of at least three large domains with different orientation of the large-scale fabric
separated by sutures cutting most likely the whole lithosphere. Boundaries of the units are characterised by a null or small
shear-wave splitting, as well as by smaller values in the P-residual spheres. We present self-consistent 3D anisotropic models
of the lithosphere domains of the BM resulting from joint inversion of anisotropic parameters searching for a 3D orientation
of mantle fabric. While in the Saxothuringian and Sudetes parts of the BM the (a, c) foliations dip prevailingly to the N-NW,
they dip to the S and SW in the southern and eastern parts of the Moldanubian. 相似文献
984.
Z. Nadenik 《Studia Geophysica et Geodaetica》2005,49(3):277-288
In modern geodesy the triaxial ellipsoid as a generalisation of the ellipsoid of revolution has a significant position in studying the figure of the Earth. Lame surfaces represent a generalisation of the triaxial ellipsoid. The following paragraphs are devoted to curvatures of the Lame surfaces. 相似文献
985.
The importance of sampling frequency in the course of monitoring of mutagenic pollution of small rivers is shown, the Kotorosl River (a tributary of the Volga River) being taken as an example. In working out a sampling program, due consideration should be given for seasonal variations of the river hydrological regime and input of pollutants. Incorrect choice of sampling frequency may lead to one of the principal reasons for improper assessment of toxicogenetic situation. A water sampling program has been proposed for the Kotorosl River studies based on monitoring.__________Translated from Vodnye Resursy, Vol. 32, No. 3, 2005, pp. 347–351.Original Russian Text Copyright © 2005 by Fomicheva, Prokhorova. 相似文献
986.
A Possible Detection of the 26 December 2004 Great Sumatra-Andaman Islands Earthquake with Solution Products of the International GNSS Service 总被引:1,自引:0,他引:1
J. Kouba 《Studia Geophysica et Geodaetica》2005,49(4):463-483
The main goal of this work is to critically review the IGS solution products and Precise Point Positioning (PPP) in order
to demonstrate their potential to contribute to studies of large earthquakes such as the one that devastated Southeast Asia
on December 26th, 2004. In view of a possible detection of the Mw 9.0 Sumatra-Andaman Islands Earthquake of December 26, 2004,
position solutions, ranging from intervals of years to one second, of four International GNSS Service (IGS) stations within
3000 km of the epicenter were examined. The IGS combined, cumulative solution product (IGS04P51), consisting of epoch and
station velocity solutions and based on data spans of several years prior to the earthquake, was used as a reference. Four
IGS combined weekly position solutions (igs04P1301-4), two weeks before and after the earthquake, were utilized for the weekly
solution resolution. PPP static and kinematic solutions with IGS Final combined orbits and clocks were used for the mean daily
and instantaneous 5-min and 1-sec epoch solutions, respectively. The most significant changes, detected by both weekly and
daily solutions occurred in longitude. The nearest IGS station ntus, about 1000 km east of the epicenter, moved westward about
15 mm, while the more distant Indian station iisc (∼ 2300 km NW from the epicenter), shifted about 15 mm eastward. In spite
of position errors caused by interpolation of the 5-min IGS clocks, the 1-sec solutions, based on separate data sets, available
only for two stations (iisc, dgar), still showed seismic surface waves, in particular at the Indian station iisc. Precise
daily IGS combined polar motion and length-of-day products, after correcting for the atmospheric effects, also likely detected,
statistically significant, anomalistic excitations on December 26, 2004 that could be caused by this great earthquake. 相似文献
987.
Mathematical modeling is used to study the conditions of natural biotransformation of biogenic element compounds (containing C, N, P, Si) in five areas within Aniva Bay. The input data for the model are evaluated with the use of GIS “Sakhalin Shelf” and the available reference literature on the bay oceanography. Water masses that transferred through the boundaries between the areas were evaluated based on the values of water level, river runoff, atmospheric precipitation, evaporation, and the volume of water in the bay, all of which vary as a result of water heating. The model was used to evaluate annual variations in the concentrations of organic and mineral fractions of these elements and the biomasses of planktonic organisms for the five areas in the bay. Modeling results also allowed the assessment of biogenic substance input with river runoff into Lososei Bay. Based on the internal fluxes of substances, the monthly and annual aquatic animal production was evaluated. 相似文献
988.
Comparative characteristic of several microelements (Ni, Cu, Sr, Al, Zn, Co, Mn, Pb, Cd, Hg, As) found in fish (case study of breams in the Volga basin reservoirs) is presented. Regularities of accumulation of these elements in fish depending on their concentration in the water are analyzed. Main disturbances in fish caused by the accumulation of microelements in their organs and tissues are considered. 相似文献
989.
990.
During the last 30 years, the methodology for assessment of undiscovered conventional oil and gas resources used by the Geological
Survey has undergone considerable change. This evolution has been based on five major principles. First, the U.S. Geological
Survey has responsibility for a wide range of U.S. and world assessments and requires a robust methodology suitable for immaturely
explored as well as maturely explored areas. Second, the assessments should be based on as comprehensive a set of geological
and exploration history data as possible. Third, the perils of methods that solely use statistical methods without geological
analysis are recognized. Fourth, the methodology and course of the assessment should be documented as transparently as possible,
within the limits imposed by the inevitable use of subjective judgement. Fifth, the multiple uses of the assessments require
a continuing effort to provide the documentation in such ways as to increase utility to the many types of users.
Undiscovered conventional oil and gas resources are those recoverable volumes in undiscovered, discrete, conventional structural
or stratigraphic traps. The USGS 2000 methodology for these resources is based on a framework of assessing numbers and sizes
of undiscovered oil and gas accumulations and the associated risks. The input is standardized on a form termed the Seventh
Approximation Data Form for Conventional Assessment Units. Volumes of resource are then calculated using a Monte Carlo program
named Emc2, but an alternative analytic (non-Monte Carlo) program named ASSESS also can be used.
The resource assessment methodology continues to change. Accumulation-size distributions are being examined to determine how
sensitive the results are to size-distribution assumptions. The resource assessment output is changing to provide better applicability
for economic analysis. The separate methodology for assessing continuous (unconventional) resources also has been evolving.
Further studies of the relationship between geologic models of conventional and continuous resources will likely impact the
respective resource assessment methodologies. 相似文献