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1.
Factors controlling typhoons and storm rain on the Korean Peninsula during the Little Ice Age 总被引：1，自引：0，他引：1
2.
It is shown that the dependence of the variations of vertical component of the polar cap magnetic field on the sector structure (actually, the azimuthal or Y component) of the interplanetary magnetic field as first discovered by Svalgaard (1968) and Mansurov (1969) extends to variations as brief as 1 hr or even less. The relation between sector structure dependent variations and substorm fields as indicated by the southward-directed component of the interplanetary magnetic field is investigated by comparing brief variations over selected intervals of time. The independence of the variations of the polar cap vertical and horizontal components suggests that there are at least two different current systems which produce brief variations in the polar cap. One of the current systems is related to the substonn field; the other is strongly seasonally dependent and is confined to the dayside sector of the Earth. 相似文献
3.
It is shown that a significant part, if not all, of the DP-2 variation can reasonably be explained by the combined effect of the equatorward expansion of the permanent Sqp current system and its enhancement. Both phenomena are now found to be controlled by the northsouth component of interplanetary magnetic field. Thus, it is concluded that the DP-2 variation arises from a modulation of the permanently existing Sqp current system by the interplanetary magnetic field, rather than by an intermittent growth of a particular type of current system. 相似文献
4.
The magnetic fields produced by a three-dimensional current system, consisting of a flow into the morning part of the auroral oval along tail-like field lines, along the auroral oval and out from the evening part of the oval along tail-like field lines, are computed. It is demonstrated that the major parts of the well-known ‘positive bay’ in low latitudes on the Earth's surface, the positive H variation at the synchronous distance and the positive Bs variation along the magnetotail during magnetospheric substorms can be caused by the proposed current system. 相似文献
5.
Makoto Yamada Shinji Ohsawa Kohei Kazahaya Masaya Yasuhara Hiroshi Takahashi Kazuhiro Amita Hideo Mawatari Shin Yoshikawa 《Journal of Geochemical Exploration》2011
To understand deep groundwater flow systems and their interaction with CO2 emanated from magma at depth in a volcanic edifice, deep groundwater samples were collected from hot spring wells in the Aso volcanic area for hydrogen, oxygen and carbon isotope analyses and measurements of the stable carbon isotope ratios and concentrations of dissolved inorganic carbon (DIC). Relations between the stable carbon isotope ratio (δ13CDIC) and DIC concentrations of the sampled waters show that magma-derived CO2 mixed into the deep groundwater. Furthermore, groundwaters of deeper areas, except samples from fumarolic areas, show higher δ13CDIC values. The waters' stable hydrogen and oxygen isotope ratios (δD and δ18O) reflect the meteoric-water origin of that region's deep groundwater. A negative correlation was found between the altitude of the well bottom and the altitude of groundwater recharge as calculated using the equation of the recharge-water line and δD value. This applies especially in the Aso-dani area, where deeper groundwater correlates with higher recharge. Groundwater recharged at high altitude has higher δ13CDIC of than groundwater recharged at low altitude, strongly suggesting that magmatic CO2 is present to a much greater degree in deeper groundwater. These results indicate that magmatic CO2 mixes into deeper groundwater flowing nearer the magma conduit or chamber. 相似文献
6.
Compaction of a Rock Fracture Moderated by Competing Roles of Stress Corrosion and Pressure Solution 总被引：1，自引：0，他引：1
Unusually rapid closure of stressed fractures, observed in the initial stages of loading and at low temperatures, is examined
using models for subcritical crack growth and pressure solution. The model for stress corrosion examines tensile stress concentrations
induced at the Hertzian contact of propping fracture asperities, and mediates fracture growth according to a kinetic rate
law. Conversely, pressure solution is described by the rate-limiting process of dissolution, resulting from the elevated stresses
realized at the propping asperity contact. Both models are capable of following the observed compaction of fractures in novaculite.
However, closure rates predicted for stress corrosion cracking are orders of magnitudes faster than those predicted for pressure
dissolution. For consistent kinetic parameters, predictions from stress corrosion better replicate experimental observations,
especially in the short-term and at low temperature when mechanical effects are anticipated to dominate. Rates and magnitudes
of both stress corrosion and pressure solution are dependent on stresses exerted over propping asperities. Rates of closure
due to stress corrosion cracking are shown to be always higher than for pressure solution, except where stress corrosion ceases
as contact areas grow, and local stresses drop below an activation threshold. A simple rate law is apparent for the progress
of fracture closure, defined in terms of a constant and an exponent applied to the test duration. For current experimental
observations, this rate law is shown to replicate early progress data, and shows promise to define the evolution of transport
properties of fractures over extended durations. 相似文献
7.
Ogawa Toshio Tanaka Yoshikazu Huzita Akira Yasuhara Michihiro 《Planetary and Space Science》1975,23(5):825-830
Three dimensional electric fields were measured at the altitude of about 27 km in the stratosphere over the Pacific Ocean about 200–400 km away from the Sanriku coast of Honsyu Island (L = 1·4) on 16–17 October 1973, which was magnetically disturbed. The average horizontal electric field thus measured is about 10 mV/m, and the electric field vectors made clockwise semidiurnal rotations rather than diurnal. Daily variation of this electric field was compared with data at L = 2·7–3·5 published by Mozer (1973) and was found to be very similar. This suggests that these electric fields are of common origin in the plasmasphere. From their mean daily variation it is estimated that the plasmaspheric convection is decreased in the night side and is increased in the day side by 200–300 m/sec, and there is an outward flow in the first half of the afternoon and an inward flow in the plasma bulge region of about 500 m/sec. 相似文献
8.
Masaya Saitou 《Astrophysics and Space Science》1989,162(1):47-56
Some peculiarities in the behaviour of a model self-gravitating system described by hydrodynamical equations and isothermal equation of state connected with the presence of thermodynamical fluctuations in real systems were investigated in numerical experiment. The values of density and velocity , , respectively, were computed by numerical code perturbed on each time-step and in each computational cell by random values , for modeling such fluctuations. Perturbed values
i
=
i
+
i
,v
i
=
i
+ v
i
were used to initiate the next step of computations. This procedure is equivalent to an introduction into original hydrodynamical equations of Langevin sources which are random functions. It is shown that these small fluctuations (= v =0,2 =v
2 = 10–8) grow many times in marginally-stable state. 相似文献
9.
Previous genetic studies on perch (Perca fluviatilis L.) in northern and southern regions of Europe have shown low heterozygosity. No such investigation has been conducted in the central part of Europe. The genetic variability ofP. fluviatilis in four Swiss lakes (Lake Constance, Lake Zürich, Lake Geneva and Lake Maggiore) was investigated. These four lakes belong to three different drainage systems (Rhine, Rhone and Po) without connections. A total of 136 fish were analysed electrophoretically. Only one locus (SOD
*) was highly polymorphic in Lake Constance among the 27 loci studied. The expected heterozygosities for each population and for the total population were higher than in the previous studies but low (H
S= 0.38–2.7%;H
T=1.22%) and Nei's genetic distances were small (0.000–0.003). However, the jack-knifed mean of the Wright'sF
STwas calculated as 0.142, which indicates modest genetic differentiation among the perch populations in Switzerland, due to the differentiated population in Lake Constance. 相似文献
10.
We propose a model three-dimensional current system for the magnetospheric substorm, which can account for the new findings of the field-aligned and ionospheric currents obtained during the last few years by using new techniques. They include (1) the ionospheric currents at the auroral latitude deduced from the Chatanika incoherent scatter radar data, (2) the field-aligned currents inferred from the vector magnetic field observations by the TRIAD satellite and (3) the global distribution of auroras with respect to the auroral electrojets appearing in DMSP satellite photographs. The model current system is also tested by a computer model calculation of the ionospheric current pattern. It is shown that the auroral electrojets have a strong asymmetry with respect to the midnight meridian. The westward electrojet flows along the discrete aurora in the evening sector, as well as along the diffuse aurora in the morning sector. The eastward electrojet flows equatorward of the westward electrojet in the evening sector. It has a northward component and joins the westward electrojet by turning westward across the Harang discontinuity. Thus, the latitudinal width of the westward electrojet in the morning sector is much larger than that in the evening sector. The field-aligned currents, consisting of two pairs of upward and inward currents (one is located in the morning sector and the other in the evening sector), are closed neither simply by the east-west ionospheric currents nor by the north-south currents, but by a complicated combination of the north-south and east-west paths in the ionosphere. The magnetospheric extension of the current system is also briefly discussed. 相似文献