共查询到20条相似文献，搜索用时 31 毫秒
1.
Geomagnetism and Aeronomy - Macroscopic discontinuous structures observed in the solar wind are considered in the framework of magnetic hydrodynamics. The interaction of strong discontinuities is... 相似文献
2.
The atmosphere is a kind of fluid surrounding therotating earth, and its state can be described by thevelocity vector v, the temperature T, the density ρ, andthe pressure p at each point. Its evolution process isessentially governed by the Navier-Stockes equationand the temperature equation. Due to the specialty andthe complexity of the atmospheric problem, althoughsome modified and simplified work have made onthese fluid mechanics and temperature equations, theyare still a very complex forc… 相似文献
3.
Water Resources - Aliphatic and polycyclic aromatic hydrocarbons have been studied in suspended matter and bottom sediments at the geochemical barrier the Northern Dvina–Dvina Bay during... 相似文献
4.
E. V. Pomozov 《Geomagnetism and Aeronomy》2014,54(1):127-134
In the used model, the quasistationary electric field in the atmosphere of the Earth is obtained by solving the conductivity equation. The penetration characteristics of the electric field from the Earth’s surface into the ionosphere depend on both atmospheric and ionosphere conductivity. The ionosphere is taken into account by setting a special condition on the upper boundary of the atmosphere. The influence of the atmospheric surface layer with a reduced conductivity on the penetration of the electric field from the surface of the Earth into the ionosphere is analyzed. 相似文献
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6.
The volume of Earth's oceans may be determined by a dynamic mechanism involving exchange of water between the crust and the mantle. Fast-spreading mid-ocean ridges are currently submerged to a depth at which the pressure is close to the critical pressure for seawater. This ensures optimal convective heat transport and, hence, maximal penetration of hydrothermal circulation along the ridge axes. The oceanic crust is hydrated to a depth of a kilometer or more and can therefore carry a substantial flux of water to the upper mantle when it is subducted. The current ingassing rate of water by this process is probably at least sufficient to balance the outgassing rate. If the oceans were shallower, as they may have been in the distant past, convective heat transport would be reduced and the depth of hydrothermal penetration and crustal hydration would decrease. Outgassing would exceed ingassing and ocean volume would increase. The system is self-stabilizing as long as the depth of the oceans does not exceed its present value. This mechanism could explain why continental freeboard has remained approximately constant since the Archean despite probable increases in continental area. 相似文献
7.
The suprabenthos comprises all bottom-dependent animals, mainly crustaceans (including decapods and peracarids), which perform--with varying amplitude, intensity and regularity--seasonal or daily vertical migrations above the sea floor. The presence of organisms in the Benthic Boundary Layer is determined by two general factors: (1) organism behaviour, which depends on the light penetration in the water column and (2) boundary-layer hydrodynamics. In the coastal zone of the eastern English Channel, during the spring Phaeocystis bloom, the presence of gelatinous colonies modifies the penetration of light in the water column, which may seriously affect the abundance and/or the behaviour of the suprabenthos community. To clarify this point, 19 suprabenthic hauls were taken with a modified Macer-GIROQ sledge both during the day and during the night, from March to June 2002 (i.e., before, during and after the bloom). Two sites, located in the coastal and offshore areas of the Ophelia medium sand macrobenthic community were investigated. The bloom had no effect on species richness and abundance in either site. However, the diel migrations of some dominant species--such as the cumaceans Pseudocuma longicornis and Pseudocuma similis, the mysid Gastrosaccus spinifer and the amphipod Stenothoe marina--were modified. During the bloom, diurnal and nocturnal suprabenthic abundances were similar, and in the absence of bloom, species remained benthic during the day. The permanent presence of suprabenthic species in the Benthic Boundary Layer could have a consequence on their predation by fish (mainly juveniles which preferentially consume small crustaceans in their diet), unless fish behaviour and predation efficiency--especially for visual predators--are also disturbed by changes in light intensity. 相似文献
8.
Dynamical diagnosis of the breakup of the stratospheric polar vortex in the Northern Hemisphere 总被引：3，自引：0，他引：3
The research on climate change in polar regions, especially on the role of polar in the global climate system, has gain unprecedented level of interest. It has been the key scientific issue of the International Polar Year program (IPY, 2007―2008). In this paper, we dealt with the debate upon the breakup time of the stratospheric polar vortex in boreal spring. An observational study of the relation between strato- spheric polar vortex breakup and the extra-tropical circulation was performed. The mean breakup date―when the winter westerly at the core of polar jet turns to summer easterly―is about April 10. The breakup time has large interannual variation with a time span of about 2 months. It also has a long-term trend with the 1990s and 2000s witnessing more and more late breakups of polar vortex. Composite of wind speed at the core of polar jet for the extremely early and late breakup years shows that late years have two periods of westerly weakening while early breakup years have only one. The first weakening in the late years happens in middle January with wind speed dropping sharply from more than 40 m s?1 to about 15 m s?1. This is accompanied with anomalous activities of planetary waves in both strato- sphere and troposphere; while the second weakening in the late breaking years is mainly the results of diabatic heating with very weak wave activities. In early breakup years, the transition from westerly to easterly is rapid with wind speed dropping from more than 30 m s?1 to less than ?10 m s?1 within a month. This evolution is associated with a strong bidirectional dynamical coupling of the stratosphere and troposphere. The circulation anomalies at low troposphere are also analyzed in the extremely early and late breakup years. It shows that there are significant differences between the two kinds of extreme years in the geopotential height and temperature composite analysis, indicating the dynamical cou- pling of stratosphere and troposphere with the evolution of stratospheric polar vortex. 相似文献
9.
Analysis of fault outcrops and trench sections indicates fault displacements of 0.2m - 6.0 m on the bottom paleosol layer of the Epipleistocene with the maximum rate of 0.047 mm/a and an average displacement of 1.1 meters. The activity appears as fissures on the fault surface in the late Epipleistocene and there is no obvious displacement. The fault activity is weak and the most active segment is the Bailuyuan segment. 相似文献
10.
S. S. Znatkova E. E. Antonova M. S. Pulinets I. P. Kirpichev 《Geomagnetism and Aeronomy》2013,53(6):699-710
We describe a method for determining the thickness of the low-latitude boundary layer (LLBL) of the Earth’s magnetosphere at the dayside near the equatorial plane based on the data gathered by a single satellite that traverses the layer and measures the plasma velocity. The method may be applied when the position of the magnetopause and the magnetosheath parameters fluctuate. The necessity of taking the presence of outer and inner LLBL regions into account is analyzed. The developed method is tested using the analysis results of two almost simultaneous close traverses of the magnetopause completed by the THEMIS mission satellites that provided relatively precise data on the LLBL thickness. It is shown that the developed method makes it possible to determine the LLBL thickness with an accuracy of ～10%. 相似文献
11.
The profile crossing the west Kunlun region cov-ers the area between the Tarim Basin and the Kara-korum Fault, which is the highest (~5000 m a.s.l.) andthe most narrow part (400—500 km from north tosouth) of the Tibetan Plateau, thus attracting great at-tention of the geological community because of itsunique tectonic features. The Geological Bureau of Xinjiang Uygur Auton-omous Region and Chinese Academy of Sciences(CAS) carried out mineral exploration and geologicalmapping in th… 相似文献
12.
YIN Hongfu CHEN Guojin LI Chang抋n & WEI Yuan . School of Earth Sciences China University of Geosciences Wuhan China . Hydrogeological Team Hubei Bureau of Geology Mineral Resources Jingzhou China . Geological Survey of Jiangxi Province Nanchang China 《中国科学D辑(英文版)》2004,47(5)
1 Origin, process and method of the research Silt deposition created the fertile Dongting and Jianghan Plains of the middle Yangtze drainage, but has become a main cause of the deteriorating flooding along the middle Yangtze. The history of flood and waterlog of the Yangtze River in last century, esp. the disastrous 1998 flood, has proved that the key to the Yangtze flood control is its middle reach, especially the Jingjiang Segment. To study the silt deposition of the middle Yangtze and … 相似文献
13.
All existing data (6 years) on gravity wave activity, inferred from the nighttime A3 (oblique incidence on the ionosphere) radio wave absorption measurements in the lower ionosphere on 270 kHz at Prhonice in Central Europe, have been exploited to get information on the effects of QBO phases and the Mt. Pinatubo volcanic eruption on the gravity wave activity in the winter half of the year. There appears to be an enhancement of gravity wave activity in the two winters just after the strong volcanic eruption of Mt. Pinatubo. This enhancement is remarkable for long-period waves (T=2–3 hours). No clear effect of the phase of QBO on the level of gravity wave activity has been found; a possible effect of QBO on the correlations between gravity wave activities in individual period bands is indicated. The results are limited by a relatively short data series; however, no more data will he available. 相似文献
14.
The rotation of the Earth's liquid core creates the Nearly Diurnal Free Wobble (NDFW). It is one of the problems of researching the Earth's liquid core for us to retrieve the parameters of the Earth's Free Core Nutation (FCN), from the Earth's liquid core resonance of gravity tide waves on the diurnal frequency band. Since 1987, some scientists in many different countries have come to calculate the parameters of FCN by using the observational data of gravity tide waves on the diurnal frequency band. They basically followed the Stacking method, which needed five diurnal waves for the resolution. In this paper, authors introduced the Akp-Btk value method with clearly geometrical meaning as a new method, which only requires three very high signal-noise-ratio waves O1, K1 and P1 for the resolution. Authors chose the observational data of the three superconducting gravimeter stations respectively located in Cantley of Canada, Wuhan of China and Brussels of Belgium, to compute the parameters of FCN. It was the first time that the observational results of the parameters of FCN obtained from gravitational tide were in accord with the parameters of FCN gained from VLBI since 1987. 相似文献
15.
V. V. Adushkin N. G. Gamburtseva M. A. Nesterkina I. A. Sanina D. D. Sultanov O. A. Usol’tseva 《Izvestiya Physics of the Solid Earth》2010,46(3):244-256
The results of long-term sounding of the lithosphere by seismic waves from the deep-focus Hindu Kush earthquakes are presented.
The travel time series of the first longitudinal wave on a fixed base are constructed for six seismic observation stations
(SS) located on the Russian Platform (the Obninsk SS), on the Siberian Platform (the Eltsovka SS), on the Cis-Ural Trough
(the Arti SS), in the Central-Ural Megazone (the Sverdlovsk SS), in the Transbaikalia (the Bodaibo SS), and in the Northern
Tien Shan (the Przhevalsk SS). The time series duration in years for these stations ranged from 1964–1970 to 2007. The travel
time series of seismic waves for the stations indicated are characterized by multi-slope negative linear trends caused by
changes in the stress-strain state of rocks. From the comparison of the trend slopes at different stations it follows that
the changes in the stress conditions within the lithosphere are relatively weak in the aseismic regions of the Russian and
Siberian Platforms and in the Ural Megazone, whereas in the seismically active regions of Tien Shan, Transbaikalia and the
Cis-Ural Trough they are more pronounced. The correlation has been observed between the time series trends of the average
annual travel times of seismic waves and the time series of the Earth’s rotation speed. The strongest correlation between
the series can be seen for the stations, located on the platforms with weak manifestations of both seismicity and active geodynamic
processes. Within the long-term periods of deceleration and acceleration of the Earth’s rotation, travel times of seismic
waves are decreased and increased, respectively. 相似文献
16.
LI Qiugen LIU Shuwen HAN Baofu WANG Yueran & DANG Qingning The Key Laboratory of Orogenic Belts Crustal Evolution Ministry of Education School of Earth Space Sciences Peking University Beijing China 《中国科学D辑(英文版)》2005,48(10)
Clastic sedimentary rocks record a number of in-formation about the compositions and paleoweathering conditions of the source areas, and the tectonic setting of the depositional basin[1―6]. The traditionallypetrological study commonly utilizes the major com-ponents (Quartz, Feldspar and Lithics) of the silici-clastic sedimentary rocks to investigate the source rock composition and tectonic setting[7]. However, thepetrological method is somewhat limited, because many of the mafic components f… 相似文献
17.
V. V. Adushkin A. A. Spivak V. A. Kharlamov 《Izvestiya Physics of the Solid Earth》2018,54(6):859-871
The results of processing and analyzing the instrumental observations of the Earth’s magnetic field at the Geophysical Observatory Mikhnevo of the Institute of Geosphere Dynamics of the Russian Academy of Sciences (IGD RAS) for 2010–2015 are presented. Quasi-harmonic components with the periods close to the lunar–solar tidal waves are revealed in the spectra of geomagnetic variations over a period of 0.4 to 30 days. The elliptical S1 tidal wave which is detected in the geomagnetic variations has modulations with periods of 1/3, 1/2, and 1 year. The spectra of the geomagnetic variations contain peaks corresponding to the free oscillations of the Earth. The analysis of the time series of the magnetic field for the period of the strong earthquakes in the absence of geomagnetic disturbances revealed the fine structure of the Earth’s fundamental spheroidal mode 0S2, which splits into five singlets. The established features of the spectrum of geomagnetic variations are helping the development of the new method for studying the deep structure of the Earth and the properties of the inner geospheres for estimating the viscosity of the Earth’s outer core and dynamics of the current systems in the outer (liquid) core, as well as for exploring, with the use of empirical data, the general regularities governing the regimes of energy exchange processes in the geospheres. 相似文献
18.
Hui Wang Kexiu Liu Aimei Wang Jianlong Feng Wenjing Fan Qiulin Liu Yao Xu Zengjian Zhang 《Ocean Dynamics》2018,68(4-5):485-495
Based on coastal tide level, satellite altimetry, and sea surface temperature (SST) data of offshore areas of China’s coast and the equatorial Pacific Ocean, the regional characteristics of the effects of the El Niño-Southern Oscillation (ENSO) on the sea level in the China Sea were investigated. Singular value decomposition results show a significant teleconnection between the sea level in the China Sea and the SST of the tropical Pacific Ocean; the correlation coefficient decreases from south to north. Data from tide gauges along China’s coast show that the seasonal sea-level variations are significantly correlated with the ENSO. In addition, China’s coast was divided into three regions based on distinctive regional characteristics. Results obtained show that the annual amplitude of sea level was low during El Niño developing years, and especially so during the El Niño year. The ENSO intensity determined the response intensity of the annual amplitude of the sea level. The response region (amplitude) was relatively large for strong ENSO intensities. Significant oscillation periods at a timescale of 4–7 years existed in the sea level of the three regions. The largest amplitude of oscillation was 1.5 cm, which was the fluctuation with the 7-year period in the South China Sea. The largest amplitude of oscillation in the East China Sea was about 1.3 cm. The amplitude of oscillation with the 6-year period in the Bohai Sea and Yellow Sea was the smallest (less than 1 cm). 相似文献
19.
V. O. Mikhailov M. Diament A. A. Lyubushin E. P. Timoshkina S. A. Khairetdinov 《Izvestiya Physics of the Solid Earth》2016,52(5):692-703
The refinement of the accuracy and resolution of the monthly global gravity field models from the GRACE satellite mission, together with the accumulation of more than a decade-long series of these models, enabled us to reveal the processes that occur in the regions of large (Mw≥8) earthquakes that have not been studied previously. The previous research into the time variations of the gravity field in the regions of the giant earthquakes, such as the seismic catastrophes in Sumatra (2004) and Chile (2010), and the Tohoku mega earthquake in Japan (2011), covered the coseismic gravity jump followed by the long postseismic changes reaching almost the same amplitude. The coseismic gravity jumps resulting from the lower-magnitude events are almost unnoticeable. However, we have established a long steady growth of gravity anomalies after a number of such earthquakes. For instance, in the regions of the subduction earthquakes, the growth of the positive gravity anomaly above the oceanic trench was revealed after two events with magnitudes Mw=8.5 in the Sumatra region (the Nias earthquake of March 2005 and the Bengkulu event of September 2007 near the southern termination of Sumatra Island), after the earthquake with Mw=8.5 on Hokkaido in September 2007, a doublet Simushir earthquake with the magnitudes Mw = 8.3 and 8.1 in the Kuriles in November 2006 and January 2007, and after the earthquake off the Samoa Island in September 2009 (Mw=8.1). The steady changes in the gravity field have also been recorded after the earthquake in the Sichuan region (May 2008, Mw = 8.0) and after the doublet event with magnitudes 8.6 and 8.2, which occurred in the Wharton Basin of the Indian Ocean on April 11, 2012. The detailed analysis of the growth of the positive anomaly in gravity after the Simushir earthquake of November 2006 is presented. The growth started a few months after the event synchronously with the seismic activation on the downdip extension of the coseismically ruptured fault plane zone. The data demonstrating the increasing depth of the aftershocks since March 2007 and the approximately simultaneous change in the direction and average velocity of the horizontal surface displacements at the sites of the regional GPS network indicate that this earthquake induced postseismic displacements in a huge area extending to depths below 100 km. The total displacement since the beginning of the growth of the gravity anomaly up to July 2012 is estimated at 3.0 m in the upper part of the plate’s contact and 1.5 m in the lower part up to a depth of 100 km. With allowance for the size of the region captured by the deformations, the released total energy is equivalent to the earthquake with the magnitude Mw = 8.5. In our opinion, the growth of the gravity anomaly in these regions indicates a large-scale aseismic creep over the areas much more extensive than the source zone of the earthquake. These processes have not been previously revealed by the ground-based techniques. Hence, the time series of the GRACE gravity models are an important source of the new data about the locations and evolution of the locked segments of the subduction zones and their seismic potential. 相似文献
20.
L. P. Imaeva B. M. Koz’min V. S . Imaev N. N. Grib S. V. Ashurkov 《Journal of Seismology》2017,21(2):385-410
The paper presents the modern structural-tectonic pattern and a tectonodynamic model of the zone of interaction of the most seismically active northeastern side of the Baikal rift zone (BRZ) and the conjugate system of seismogenic structures of the Aldan-Stanovoy block, where disastrous events with M ≥ 6.0 have been reported. Regularities in the structural formation of active faults and their kinematics are discussed. The faults form block structures accumulating significant tectonic strain. Motions between large tectonic blocks cause sudden release of the strain, which results in catastrophic events (M ≥ 6.0) with focal mechanisms of definite kinematic type. 相似文献