共查询到20条相似文献,搜索用时 15 毫秒
1.
V. M. Ovtchinnikov P. B. Kaazik D. N. Krasnoshchekov 《Izvestiya Physics of the Solid Earth》2012,48(3):211-221
Experimental data on the differential travel time t
BC–t
DF of seismic waves PKPDF and PKPBC in the Earth’s core under Africa and Australia are analyzed. The differential travel-time residuals beneath Africa in a narrow
range of angles from 21° to 25° between the direction of the seismic ray in the core and the Earth’s rotation axis exhibit
a scoop-shaped peculiarity not accounted for by cylindrical anisotropy in the inner core. A model with a 0.2–0.8% P-wave velocity anomaly with a radius of 1375 km in the cylindrical region in the outer core is proposed, which closely fits
the experimental data. We suggest that the velocity anomaly is generated by the dynamical processes occurring in the outer
core, namely, the growth of the inner core and the convection in the outer core, both leading to the formation of a low-density
anomaly in the outer core. 相似文献
2.
Gunther Kletetschka Petr Schnabl Kristýna Šifnerová Zuzana Tasáryová Štěpán Manda Petr Pruner 《Studia Geophysica et Geodaetica》2013,57(1):103-117
Magnetic images have been produced at the distance of 0.1 mm from the polished basaltic thin sections of rocks from Prague Synform in Barrandian area. Three different magnetic textures were seen and when combined with optical imaging could be related to petrological features. The first magnetic texture revealed that most of the magnetic signature is localized within the amygdales formed later after the basalts became part of the sedimentary sequence. The second texture showed that the basaltic body contains large grain size distribution of magnetic carriers possibly with variable viscous magnetizations. The third texture suggested a presence of magnetic anisotropy of igneous origin. Such textural magnetic information along with the paleomagnetic characteristics of the basaltic rocks of Silurian age constrained the overall geological interpretation. 相似文献
3.
Vertical quantitative and dominant population distribution of the bacteria isolated from the Muztagata ice core 总被引:8,自引:0,他引:8
XIANG Shurong YAO Tandong AN Lizhe WU Guangjian XU Baiqing MA Xiaojun LI Zhen WANG Junxia & YU Wusheng . Key Laboratory of Ice Core Cold Regions Environment Cold Arid Regions Environmental Engineering Research Institute Chinese Academy of Sciences Lanzhou China . Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China . College of Life Science Lanzhou University Lanzhou China 《中国科学D辑(英文版)》2005,48(10)
With rapid development of microbiology on ex-treme environment, many microorganisms have been found on glacial surface and in deep glacier around the world. The extensive 16S rRNA sequence analysis of bacteria isolated from glacial samples indicates that the bacteria in ice are highly similar to those from ocean, lake, terrestrial sediment and agricultural soil on the earth[1,2]. This suggests a close relationship be-tween the microorganisms in glacial region and those in other environments s… 相似文献
4.
S. M. Molodenskii 《Izvestiya Physics of the Solid Earth》2010,46(7):555-579
When analyzing the new high-accuracy observations of the forced nutation and tidal variations in the acceleration of gravity,
it was found that they are in sharp contradiction to the present-day models of the Earth’s interior based on seismic data
and the data on the periods and damping constants of the free oscillations of the Earth. The elimination of these contradictions
requires analyzing the uniqueness of the interpretation of the free oscillations of the Earth, taking into account the new
data. 相似文献
5.
The Earth’s free core nutation (FCN) is a retrograde eigenmode which is attributed to the interaction between the solid mantle and the liquid core of the rotational elliptical Earth. 相似文献
6.
L. Egyed 《Pure and Applied Geophysics》1956,33(1):42-48
Summary It is shown that paleogeographical data give evidence for the increase of the Earth’s radius. The average annual increase
computed is 0.5 mm/year. The formation of the continents and ocean basins may be easily explained on the basis of the Earth’s
expansion. The rate of the annual radius increase derived from this explanation is in good agreement with the value determined
from paleogeographical data. The theoretically computed duration of a transgression-regression period corresponds also with
geological observations.
Prof. Dr. L. Egyed, Geophysical Institute, E?tv?s-University,Budapest (Hungary). 相似文献
7.
NIU ZhenGuo GONG Peng CHENG Xiao GUO JianHong WANG Lin HUANG HuaBing SHEN ShaoQing WU YunZhao WANG XiaoFeng WANG XianWei YING Qing LIANG Lu ZHANG LiNa WANG Lei YAO Qian YANG ZhenZhong GUO ZiQi & DAI YongJiu State Key Laboratory of Remote Sensing Science Jointly Sponsored by Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing Normal University Beijing China School of Geography Beijing Normal University Beijing 《中国科学D辑(英文版)》2009,52(6):723-738
In this paper, we report the first wetland mapping of the entire China using Landsat enhanced thematic mapper plus (ETM+) data. These data were obtained from the Global Land Cover Facility at the University of Maryland spanning from 1999 to 2002. A total of 597 scenes of Landsat images were georeferenced and mosaiced. Manual image interpretation of satellite images was aided with elevation data, soil data, land cover/land use data and Google Earth. The minimum mapping unit is 10 pixel × 10 pixel, equivalent... 相似文献
8.
S. L. Shalimov 《Izvestiya Physics of the Solid Earth》2014,50(4):463-466
The anisotropy of the convection in the Earth’s core can act as a cause of its nonsolid rotation. In the case of differential rotation, the magneto-rotational instability (the Velikhov instability) can arise in the liquid core. It is shown that the development of the magneto-rotational instability of the hydromagnetic flows in the liquid core of the Earth can generate variations in the geomagnetic field observed on the Earth’s surface. 相似文献
9.
Climatic and environmental changes over the last millennium recorded in the Malan ice core from the northern Tibetan Plateau 总被引:9,自引:0,他引:9
WANG Ninglian YAO Tandong PU Jianchen ZHANG Yongliang SUN Weizhen 《中国科学D辑(英文版)》2006,49(10):1079-1089
In this paper, climatic and environmental changes were reconstructed since 1129A.D. based on the Malan ice core from Hol Xil, the northern Tibetan Plateau. The record of δ 18O in the Malan ice core indicated that the warm-season air temperature variations displayed a general increase trend, the 20th-century warming was within the range of natural climate variability, and the warmest century was the 17th century while the warmest decade was the 1610s, over the entire study period. The “Medieval Warm Epoch” and “Little Ice Age” were also reflected by the ice core record. The dust ratio in the Malan ice core is a good proxy for dust event frequency. The 870-year record of the dust ratio showed that dust events occurred much frequently in the 19th century. Comparing the variations of δ 18O and the dust ratio, it is found that there was a strong negative correlation between them on the time scales of 101―102 years. By analyses of all the climatic records of ice cores and tree rings from the northern Tibetan Plateau, it was revealed that dust events were more frequent in the cold and dry periods than in the warm and wet periods. 相似文献
10.
A. A. Spivak 《Izvestiya Physics of the Solid Earth》2011,47(7):600-609
Nonlinear effects in seismic wave propagation are analyzed to determine the mechanical rigidity of different-order faults
that thread the tectonic structures in the central part of the East European platform (Moscow syneclise and Voronezh Crystalline
Massif) and the fault zones of the Balapan and Degelen mountain regions in Kazakhstan (the Degelen magmatic node in the Central
Chingiz zone). The dependency of the rigidity of the fault zone on the fault’s length is obtained. The rigidity of the tectonic
structures is found to experience well-expressed temporal variations with periods of 13–15 days, 27–32 days, and about one
year. In the different-order fault zones, the amplitudes of both normal k
n and the shear k
s rigidity for semimonthly, monthly, and annual variations can span a factor of 1.3, 1.5, and 2.5, respectively. 相似文献
11.
A new method for the interpretation of recent tidal and astrometry data based on integral relations connecting the mantle
Q parameters to variations in frequencies of the main Earth’s spheroidal oscillation, nearly diurnal free nutation, Chandler
wobble, and Love numbers is proposed in this paper. The normalized weighting functions in the aforementioned integral relations
are shown to be very close to each other in a wide range of oscillation periods (from 54 minutes to 14 months) for the actual
Earth’s model and therefore the detection of the dependence of the mantle Q parameters averaged with these weighting functions
on frequency does not need to be solved for the inverse problem of the Q parameters as a function of the oscillation frequency
and depth: instead, it is sufficient to determine the dependence of the adequate integral characteristics of the mantle’s
inelasticity only on frequency. This makes it possible to significantly simplify the solution of the inverse problem and improve
the rheologic models of the lower mantle. 相似文献
12.
Xiangfang Zeng Zhongwen Zhan Yong Zheng Mengcheng National Geophysical Observatory School of Earth Space Sciences University of Science Technology of China China Seismological Laboratory California Institute of Technology Pasadena CA USA CAS Key Laboratory of Dynamical Geodesy 《地震学报(英文版)》2011,(2):143-150
Estimated Green’s function (EGF) between stations has been extracted from ambient seismic noise, direct surface wave and coda waves. It is also confirmed by laboratory experiments on ultrasonics and theoretical derivations assuming diffusive wave field, equi-partition of modes or random sources on an enclosed surface. This method provides a new approach to study the crust and mantle structure at regional scale, continental scale and global scale. Following the achievements with seismometer records, the reco... 相似文献
13.
The paper presents the results of analyzing the set of dual-polarity paleomagnetic results the Global Paleomagnetic Database
(GPMDB). The dataset was expanded by the results from the Paleomagnetic Data Catalogue for the USSR and with new data published
after 2005. Some results were rejected to avoid the influence of overprints of ancient and recent magnetization. Overall,
59 dual-polarity results for the lithospheric plates of Baltica, Laurentia, and Siberia with their immediate framing were
selected for the analysis in the interval of ages 207–359 Ma. The new data confirmed the model of the paleomagnetic field,
according to which the field contains a long-lived component corresponding to the equatorial dipole which is responsible for
the non-antipodal paleomagnetic directions in the zones of normal and reverse polarity in sedimentary and volcanic rock sequences.
Retaining its value of 5–8% of the central axial dipole, the equatorial dipole changed its polarity a few times during the
interval 359–207 Ma. The northern poles of the dipole formed two antipodal groups on the Earth’s surface, which lie within
or near the subduction zones on the periphery of the Pangaea Supercontinent. Such localization of the equatorial dipole is
suggested to be related to the ascending branches of the mantle convection and to the topography of both boundaries of the
outer Earth’s core. 相似文献
14.
C.M. Green K.M.U. Fletcher S. Cheyney G.J. Dawson S.J. Campbell 《Geophysical Prospecting》2019,67(6):1611-1619
This paper reviews the impacts of new satellite altimeter data sets and new technology on the production of satellite gravity. It considers the contribution of the increased data volume, the application of new altimeter acquisition technology and the potential for future developments. Satellite altimeter derived gravity has provided gravity maps of the world's seas since the 1980s, but, from 1995 to 2010, virtually all improvements were in the processing as there were no new satellite data with closely spaced tracks. In recent years, new data from CryoSat-2 (launched in 2010) and the geodetic mission of Jason-1 (2012–2013) have provided a wealth of additional coverage and new technology allows further improvements. The synthetic aperture radar mode of CryoSat-2 uses a scanning approach to limit the size of the altimeter sea surface footprint in the along-track direction. Tests indicate that this allows reliable data to be acquired closer to coastlines. The synthetic aperture radar interferometric mode of CryoSat-2 uses two altimeters to locate sea-surface reflection points laterally away from the satellite track. In a study to generate gravity for freshwater lakes, this mode is found to be valuable in extending the available satellite coverage. The AltiKa altimeter uses higher frequency radar to provide less noisy sea-surface signals and its new orbit mode gives potential for further improvements in satellite gravity. Future developments include the potential for swath mapping to provide further gravity improvements. 相似文献
15.
M. Yu. Reshetnyak 《Izvestiya Physics of the Solid Earth》2013,49(5):675-682
The effects of adiabatic cooling on the convection in the anelastic model of the liquid core of the Earth are considered. It is shown that even minor adiabatic cooling causes significant changes in the pattern of the convection, shifting the peak in the convection intensity to the inner part of the core. Just as in the Boussinesq model, both direct and inverse kinetic energy cascades are simultaneously present, and the direct cascade of entropy is observed. 相似文献
16.
V. G. Ivanov 《Geomagnetism and Aeronomy》2012,52(8):999-1004
This paper investigates the trend towards an increase in the tilt of sunspot groups with increasing latitude (Joy??s law) and the relationship between the features of this law and solar activity parameters. In addition to the known data of the Mount Wilson and Kodaikanal observatories, the analysis uses the Pulkovo database of solar activity, which allows for the estimation of the reliability of the conclusions obtained by other authors from the first two catalogs. It is shown that Joy??s law is manifested in all three data series and has many features in common. In particular at latitudes above 25?C30°, the tilt of sunspot groups is not linearly dependent on latitude and displays a slight decrease. However, some features of this law found previously in the data of the first two observatories (e.g., a decrease in its strength with an increase in the strength of the solar cycle) are not confirmed by our analysis. 相似文献
17.
The acceleration of the industrialization process in China has increased the demand for electricity and triggered a power-plant building boom, especially along China’s eastern coast, where the economy gets off early and enjoys a fast development. The thermal plumes, residual chlorine, nuclides and other pollutions produced by the thermal and nuclear power plants have exerted an impact on the coastal eco-environment. To monitor the thermal pollution from the power plants at Yueqing Bay on the eastern coast, in this research, the distribution of sea surface temperature (SST) surrounding the power plants is obtained by using the SST retrieval methods developed for Landsat Enhanced Thematic Mapper Plus (ETM+), HJ-1B infrared sensor (IRS) and Terra moderate resolution imaging spectroradiometer (MODIS) data. The comparison of the SST retrieval results before and after the operation of power plants indicates that the total area of sea waters that is impacted by the thermal discharge from the two power plants at Yueqing Bay is approximately 17.95 km2, with the highest SST rise of 4.5 °C appearing over the waters around the outlet of the Huaneng Yuhuan power plant on the eastern shore, whereas the highest SST rise around the Zheneng Yueqing power plant on the western shore reaches 3.8 °C. The intensity and scope of influence of the thermal discharge mainly depend on the installed capacity of power plants, coastal terrain, and tide. Although the area where the SST rise is more than 3 °C is not large, thermal discharge still has an impact on bay ecosystems due to the relatively closed nature of the bay environment. Due to the influence of rising water temperatures on the reproduction and individual evolution of fish, shrimp, crabs, shellfish and other aquatic creatures, in the long term, the thermal pollution from coastal power plants will affect the volume of natural fishery and biological resources throughout the waters. The quantitative retrieval results also suggest that relative to MODIS data, Landsat ETM+ and HJ-1B IRS data with a high spatial resolution are more applicable to the estimation of small-scale SST, and IRS data with a high temporal resolution are more helpful in the study of spatio-temporal variability of thermal plumes from coastal power plants. 相似文献
18.
Ji Liu QuanQi Shi AnMin Tian JianYong Lü Hao Wu Ming Wang SuiYan Fu YuChen Yang QiuGang Zong Jiang Zhang YongYong Feng ZuYin Pu 《中国科学:地球科学(英文版)》2016,59(8):1700-1706
Earth’s bow shock is the result of interaction between the supersonic solar wind and Earth’s magnetopause. However, data limitations mean the model of the shape and position of the bow shock are based largely on near-Earth satellite data. The model of the bow shock in the distant magnetotail and other factors that affect the bow shock, such as the interplanetary magnetic field (IMF) By, remain unclear. Here, based on the bow shock crossings of ARTEMIS from January 2011 to January 2015, new coefficients of the tail-flaring angle α of the Chao model (one of the most accurate models currently available) were obtained by fitting data from the middle-distance magnetotail (near-lunar orbit, geocentric distance -20RE>X>-50RE). In addition, the effects of the IMF By on the flaring angle α were analyzed. Our results showed that: (1) the new fitting coefficients of the Chao model in the middle-distance magnetotail are more consistent with the observed results; (2) the tail-flaring angle α of the bow shock increases as the absolute value of the IMF By increases. Moreover, positive IMF By has a greater effect than negative IMF By on flaring angle. These results provide a reference for bow shock modeling that includes the IMF By. 相似文献
19.
S. M. Korotaev E. O. Kiktenko S. P. Gaidash N. M. Budnev R. R. Mirgazov A. I. Panfilov A. A. Khalezov V. O. Serdyuk V. S. Shneer 《Geomagnetism and Aeronomy》2013,53(6):769-773
Based on the data of deepwater measurements of the electric field’s vertical component in Lake Baikal, the relationship between electric field variations and those in background X-ray solar radiation has been revealed. A high correlation between these variations within periods of more than three months has been discovered. 相似文献
20.
The Earth's free core nutation (FCN) is a retrograde eigenrnode which is attributed to the interaction between the solid mantle and the liquid core of the rotational elliptical Earth. This mode appears as an eigenmode of nearly diurnal free wobble (NDFW) in a terrestrial reference frame with a period of about one day (XU et al, 2001). Therefore, the NDFW will lead to an obvious resonance enhancement in the diurnal tidal gravity observations, especially those of the tidal waves with frequencies closed to its eigenfrequency such as P1, K1, ψ1 and Ф1. The FCN resonance parameters can be retrieved accurately by high-precision tidal gravity observations, especially those recorded with the superconducting gravimeters (SG). The Global Geodynamics Project (GGP) organized by IUGG took it as an important content for determining the FCN resonance parameters by using gravity data. However, the results are affected by many factors such as station location, background noise, the selection of the tide-generating potential tables, ocean tide models, data processing techniques and so on. In our study, the FCN parameters will be retrieved by using the SG observations at Wuhan, and the effects of the choices of various tide-generating potential tables, oceanic models and weight functions on the estimation of the FCN parameters will be discussed in detail, 相似文献