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1.
The influence of auroral electojets and solar wind parameters on variations in low-latitude geomagnetic disturbances and D
st
during strong magnetic storms on November 7–8, 2004 with D
st
≈ −380 nT and on November 9–10, 2004 with D
st
≈ −300 nT is studied on the basis of global geomagnetic observations. It is found that the impulsive variations of the western
electrojet intensity with a duration of Δt ≈ 1–2 h (probably, substorm disturbances) lead to positive low-latitude disturbances of ΔH at Φ′ ≈ 10°–30° and to disturbances of the same durations with an amplitude +ΔH ∼ 30–100 nT at latitudes of the polar cap (Φ′ ≈ 75°–80°). More durable (with Δt ≥ 10 h) convection electrojets whose centers are shifted to latitudes of ∼50°–55° in the process of storm development are
the main cause of the increase in negative values of ΔH at low latitudes and D
st
. It is shown that meridional dynamics of position of the center of electrojets and the equatorial boundary of the auroral
oval is governed by variations (increase or decrease) in the intensity of negative values of the IMF B
z
component. It is assumed that in these storms the intensification of the magnetospheric partially ring current closes the
circuit to the ionosphere with the help of field-aligned currents at the equatorial boundary of the auroral oval is the main
cause of the magnetic field depression at low latitudes. 相似文献
2.
We investigate the behavior of mean values of the solar wind’s and interplanetary magnetic field’s (IMF) parameters and their
absolute and relative variations during the magnetic storms generated by various types of the solar wind. In this paper, which
is a continuation of paper [1], we, on the basis of the OMNI data archive for the period of 1976–2000, have analyzed 798 geomagnetic
storms with D
st
≤ −50 nT and their interplanetary sources: corotating interaction regions CIR, compression regions Sheath before the interplanetary
CMEs; magnetic clouds MC; “Pistons” Ejecta, and an uncertain type of a source. For the analysis the double superposed epoch
analysis method was used, in which the instants of the magnetic storm onset and the minimum of the D
st
index were taken as reference times. It is shown that the set of interplanetary sources of magnetic storms can be sub-divided
into two basic groups according to their slowly and fast varying characteristics: (1) ICME (MC and Ejecta) and (2) CIR and
Sheath. The mean values, the absolute and relative variations in MC and Ejecta for all parameters appeared to be either mean
or lower than the mean value (the mean values of the electric field E
y
and of the B
z
component of IMF are higher in absolute value), while in CIR and Sheath they are higher than the mean value. High values
of the relative density variation sN/〈N〉 are observed in MC. At the same time, the high values for relative variations of the velocity, B
z
component, and IMF magnitude are observed in Sheath and CIR. No noticeable distinctions in the relationships between considered
parameters for moderate and strong magnetic storms were observed. 相似文献
3.
D. V. Chugunin 《Cosmic Research》2009,47(6):449-459
Characteristics of polar wind fluxes at a height of ∼20000 km measured by the Hyperboloid mass-spectrometer installed onboard
the Interball-2 satellite are presented in the paper. The characteristics are presented for the upwelling flows of ionospheric ions H+, He+, and O+ from the sunlit polar cap in the period of solar activity minimum. Orbit segments with minimal precipitation of magnetospheric
ions and electrons were preliminarily selected, and the measurements where the fluxes of ions coming from the cusp/cleft were
excluded as carefully as possible. Thus, the densities, field-aligned velocities, and temperatures of ions in the regions
where fluxes of polar wind could be detected with the maximal probability degree are presented in the paper. It is found that
cases when only H+ ions are reaching the detector are with high probability the polar wind outflows. Their characteristics agree well with the
Tube-7 hydrodynamic model and are as follows: n ≈ 1.5 cm−3, V
∥ ∼ 21 km/s; T
∥ = 3500 K, and T
⊥ = 2000 K. In cases when He+ and O+ ions are also detected, the temperatures are substantially higher than the model ones, and the measured field-aligned velocities
of O+ fluxes are several times higher than the model ones. Moreover, it was revealed that the polar wind outflows are predominantly
observed in the polar cap regions where the polar rain fluxes are very small. 相似文献
4.
Based on the archive OMNI data for the period 1976–2000 an analysis has been made of 798 geomagnetic storms with D
st
< −50 nT and their interplanetary sources-large-scale types of the solar wind: CIR (145 magnetic storms), Sheath (96), magnetic
clouds MC (62), and Ejecta (161). The remaining 334 magnetic storms have no well-defined sources. For the analysis, we applied
the double method of superposed epoch analysis in which the instants of the magnetic storm beginning and minimum of D
st
index are taken as reference times. The well-known fact that, independent of the interplanetary source type, the magnetic
storm begins in 1–2 h after a southward turn of the IMF (B
z
< 0) and both the end of the main phase of a storm and the beginning of its recovery phase are observed in 1–2 h after disappearance
of the southward component of the IMF is confirmed. Also confirmed is the result obtained previously that the most efficient
generation of magnetic storms is observed for Sheath before MC. On the average parameters B
z
and E
y
slightly vary between the beginning and end of the main phase of storms (minimum of D
st
and D
st
* indices), while D
st
and D
st
* indices decrease monotonically proportionally to integral of B
z
and E
y
over time. Such a behavior of the indices indicates that the used double method of superposed epoch analysis can be successfully
applied in order to study dynamics of the parameters on the main phase of magnetic storms having different duration. 相似文献
5.
In 1964, during flights of the ELECTRON satellites the narrow belts of energetic electrons (E
e ≈ 6MeV) have been discovered in the Earth’s magnetosphere at L ≈ 2.75. The same structures approximately at the same magnetic shells were found in 2004 by the CORONAS-F and SERVIS-1 satellites. A comparison of the results of these experiments is presented. It is shown that the additional narrow belts of
energetic electrons occur after intense magnetic storms (D
st
> 100 nT), in our cases, having a double-triple structure. The lifetime of these belts is a few months and their disappearance
had a gradual character. The obtained results separated in time by 40 years suggest the constancy of the sources of particles
of the Earth’s radiation belts and processes occurring in the magnetosphere, which ensures not only existence of the radiation
belts, but also the recurrence of various exotic phenomena in the belts similar to the belt of energetic electrons at the
inner magnetic shells. 相似文献
6.
B. B. Kreisman 《Cosmic Research》2010,48(3):265-272
A technique of generation of spatial periodic solutions to the restricted circular three-body problem from periodic orbits
of the planar problem has been used for the families of orbits around collinear libration points L
1 and L
2. Developing the families obtained at the 1: 1 resonance, we have obtained stable solutions both in the Earth-Moon system
and in the Sun-Earth system. Of course, the term “around the libration point” is rather conventional; the obtained orbits
become more similar to the orbits around the smaller attracting body. The further development of the family of orbits “around”
the libration point L
2 in the Sun-Earth system made it possible to find the orbits satisfying the new, much more rigorous constraints on cooling
the spacecraft of the Millimetron project. 相似文献
7.
A. S. Kovtyukh 《Cosmic Research》2012,50(3):226-232
Satellite data on the position of maximum L m of the belt of relativistic electrons during strong storms, obtained at low altitudes (∼500 km) and at high altitudes (near the geomagnetic equator plane), are compared (L is the McIlwain parameter). Both at low and high altitudes the maximum of the storm belt of relativistic electrons is formed on the outer edge of the ring current. It is shown that the geomagnetic field can substantially deviate from dipole configuration not only at the geomagnetic trap periphery, but at its core as well (at L ∼ 2.5–3.5), and these deviations are nonlinear. Simultaneous measurements of the fluxes of relativistic electrons at low and high altitudes can serve for estimation of the real shape of magnetic field lines at L < 4 during geomagnetic disturbances. 相似文献
8.
In each polar cap (PC) we mark out “old PC” observed during quiet time before the event under consideration, and “new PC” that emerges during the substorm framing the old one and expanding the PC total area. Old and new PCs are the areas for the magnetosphere old and new tail lobes, respectively. The new lobe variable magnetic flux Ψ1 is usually assumed to be active, i.e. it provides the electromagnetic energy flux (Poynting flux) ɛ′ transport from solar wind (SW) into the magnetosphere. The old lobe magnetic flux Ψ2 is supposed to be passive, i.e. it remains constant during the disturbance and does not participate in the transporting process which would mean the old PC electric field absolute screening from the convection electric field created by the magnetopause reconnection. In fact, screening is observed, but far from absolute. We suggest a model of screening and determine its quantitative characteristics in the selected superstorm. The coefficient of a screening is the β = Ψ2/Ψ02, where Ψ02 = const is open magnetic flux through the old PC measured prior to the substorm, and Ψ2 is variable magnetic flux through the same area measured during the substorm. We consider three various regimes of disturbance. In each, the coefficient β decreased during the loading phase and increased at the unloading phase, but the rates and amplitudes of variations exhibited a strong dependence on the regime. We interpreted decrease in β as a result of involving the old PC magnetic flux Ψ2, which was considered to be constant earlier, in the Poynting flux ɛ′ transport process from solar wind into the magnetosphere. Transport process weakening at the subsequent unloading phase creates increase in β. Estimates showed that coefficient β during each regime and the computed Poynting flux ɛ′ varied manifolds. In general, unlike the existing substorm conception, the new scenario describes an unknown earlier of tail lobe activation process during a substorm growth phase that effectively increases the accumulated tail energy for the expansion and recovery phases. 相似文献
9.
10.
Combination of data on declined intensities of particles of different nature (e, p, and α) into a single dependence of characteristic decline time τ on particle rigidity in a wide range of R reveals the diversity of forms of τ(R) in different events: regular increase, decrease, and independence of R, as well as the presence in some events of maxima and minima. The problem of studying τ(R) has something in common with long standing problem of the rigidity dependence of mean free path λ(R). The considered set of forms of τ(R) allows one to conclude that at present there is no uniform dependence τ(R), as well as λ(R), and, therefore, no their common model interpretation in a wide range of rigidities exists. 相似文献
11.
B. B. Kreisman 《Cosmic Research》2012,50(1):65-75
Within the framework of the circular restricted three-body problem a family of inverse periodic orbits around the two attracting
bodies (the Egorov’s family) and families generated by it at the 1:1, 2:1, and 3:1 resonances for three-dimensional orbits
in the Sun-Earth and Earth-Moon systems are considered. Their relationship with families generated by orbits around the libration
points L
1, L
2 and L
3 is investigated. One of the families contains periodic solutions that seem promising as possible orbits for the space radio
telescope of the Millimetron project. 相似文献
12.
The surface temperature distributions due to thermocapillary convections in a thin liquid layer with heat fluxes imposed on the free surface are investigated. The nondimensional analysis predicts that, when convection is important, the characteristic length scale in the flow direction L, and the characteristic temperature difference ΔT0, can be represented by
and
, respectively, where LR and ΔTT are the reference scales used in the conduction-dominant situations with A denoting the aspect ratio and Ma the Marangoni number. Having had L and ΔT0 defined, the global surface-temperature gradient (
), the global thermocapillary driving-force, and other interesting features can then be readily determined. Finally, numerical calculations involving a Gaussian heat flux distribution are presented to justify these two relations. 相似文献
13.
Low fluxes of protons with energies 0.3–10 MeV were studied during 21–23 solar cycles as a function of the MgII index using the data of the instruments CPME, EIS (IMP8), and EPHIN (SOHO). It has been shown that a) during quiet time of solar activity the fluxes of protons (background protons) have a positive
correlation with the MgII index value throughout the solar cycle, b) specific features of variations of the MgII index during the solar minima of 1986–1987 and 1996–1997 can be considered, as well as variations of background fluxes of
low energy charged particles, to be manifestations of the 22-year magnetic cycle of the Sun, and c) periods of the lowest
value of the MgII index are also characterized by the smaller values of the ratio of intensities of protons and helium nuclei than in other
quiet periods. A hypothesis is put forward that acceleration in a multitude of weak solar flares is one of the sources of
background fluxes of low energy particles in the interplanetary space. 相似文献
14.
Statistical properties of magnetic field and plasma flux fluctuations outside the Earth’s magnetosphere are studied on various
time scales based on the INTERBALL-1 satellite data. The analysis of “rough” turbulence characteristics has shown that turbulence properties in various parts
of the magnetosheath are distinct. The spectral density of the magnetic field undergoes a break at a frequency of ∼0.5 Hz.
As a more “fine” characteristic of the fluctuations on various time scales, changes in the shape and parameters of the probability
density function were studied. The analysis of the height of a maximum of the probability density function P(0) and of the kurtosis values have shown the presence of two asymptotic modes of P(0), which are characterized by different power laws. The critical scale, on which the properties of P(0) change, corresponds, presumably, to the scales of the Larmor radius of ions. Based on the results of studying structural
functions of various orders, the conclusion is drawn that small-scale turbulence in the foreshock and magnetosheath is described
by different phenomenological models. 相似文献
15.
The evolution of seismo-ionospheric disturbances accompanied strong destructive earthquakes in the region of Kuril and Japan
Islands on October 4, 1994, September 25, 2003, and November 15, 2006 is studied in the paper. For determination of the dynamics
of spatial-temporal and amplitude parameters of disturbances in the total electron content (TEC) on the basis of the Japan
network of receiving GPS stations GEONET and Korean network KGN, the method of drawing “distance-time” diagrams and quasi-optimal
algorithm of spatial-temporal processing of the GPS network data was used. The ionospheric response was detected at a distance
D from the epicenter up 2500 km. The maximal value of the disturbance amplitude is observed at D = 400–600 km. For the September 25, 2003 and November 15, 2006 earthquakes, the velocity V of propagation of the dominant disturbance mode is independent of the distance and equal to 850 and 1100 m/s, respectively.
At a distance D ∼ 600 km, the wave disturbance from the main shock of the October 4, 1994 earthquake is split into two modes: the velocity
of the “fast mode” of the disturbance increases with distance from 1500 to 2400 m/s, while the velocity of the “slow mode”
V = 600 m/s does not depend on D. Possible interpretation of the obtained results is given. 相似文献
16.
Estimates of drag characteristics of the space vehicles with orbit heights of 450–540 and 700–900 km before and after strong
(with a magnitude M ≥ 6.5) crust earthquakes of 2000–2006 are presented. The method of estimation of seismic orbital effects is presented using
as an example the small Mozhaets-4 spacecraft. Two weeks prior to earthquakes, variations in the drag of low-orbital spacecraft increase. 3–6 days prior to
strong crust earthquakes with epicenters on the land, the drag of low-orbit spacecraft in the upper atmosphere increases.
The effect of increased viscosity of the neutral component of the atmosphere at spacecraft heights 3–6 days prior to strong
crust earthquakes is consistent with the results of studies of disturbances in the ionization density variations in the ionospheric
F region prior to earthquakes. No anomalies are found in the day of the earthquake. In the future, it is proposed to use elements
of space debris for diagnostics of seismic orbital effects and disturbances of the upper atmosphere. 相似文献
17.
Analyzing the results of space and ground-based experiments carried out in the Baikov Institute of Metallurgy and Materials Science to study the processes of the melting and crystallization of two-phase InSb–InBi alloys of an indium–antimony–bismuth (In–Sb– Bi) triple system, we have demonstrated the gravitational sensitivity of the InSb-based solution– melt. It manifests itself as a certain asymmetry of the boundary of the dissolution of the InSb ingot by the InSb–InBi melt and heterogeneity of the melt along this boundary depending on the magnitude and direction of the gravity force acceleration gin the range (1–10–3–10–5)g
0, where g
0is the acceleration of the gravity force on Earth. For the first time, it is established in the experiments under analysis that the homogeneity of melts of a complex composition with components of various densities can be reached only at magnitudes of quasistationary (residual) microaccelerations g< 10–6
g
0. 相似文献
18.
Fluxes of trapped protons with energies above 70 MeV measured onboard the NOAA-15 satellite during the 23rd solar activity cycle (from 1999 to 2006) are analyzed. Comparing to similar experimental data obtained
for 1976–1996, regularities of changes in the proton flux at low drift shells (L = 1.14–1.20) of the Earths’s radiation belt caused by changes in the solar activity are discussed. 相似文献
19.
N. A. Vlasova N. N. Pavlov M. I. Panasyuk N. N. Vedenkin T. A. Ivanova G. P. Lyubimov S. Ya. Reizman V. I. Tulupov 《Cosmic Research》2011,49(6):485-499
We compared fluxes of the 1–100 MeV solar energetic particles (SEP) measured in the interplanetary medium (ACE) and in the magnetosphere (Universitetsky-Tatiana, POES—in polar caps, and GOES-11—at geosynchronous orbit) during several SEP events of 2005–2006. Peak intensities of the SEP fluxes inside and outside the
magnetosphere were compared for each event. It is shown that observed inside-outside difference depends mainly on direction
of interplanetary magnetic field (IMF), on degree of the SEP anisotropy (pitch-angle distribution) in IMF, and on distance
of the dayside magnetopause from the Earth. 相似文献
20.
A theoretical and experimental study is carried out to determine the effect of buoyancy on the rate of spread of a cocurrent smolder reaction through a porous combustible material. Since buoyant forces are proportional to the product g(gi − g), they can be controlled experimentally by varying either the gravitational acceleration, g, or the density difference, gi − g. The latter approach was followed in the present work. Measurements are performed of the smolder spread rate through porous α-cellulose (0.83 void fraction) as a function of the ambient air pressure. The experiments are carried out in a pressure vessel for ambient pressures ranging from 0.5 to 1.2 atm. The rate of spread was obtained from the temperature histories of thermocouples placed at fixed intervals along the fuel centerline. The smolder velocity was found to increase as the ambient pressure was increased. Extinction was found to occur when the buoyancy forces could not overcome the drag forces, indicating that at least for the present experimental conditions transport by diffusion cannot, by itself, support the spread of a smolder reaction. This conclusion is particularly important for outer space conditions where gravity and consequently buoyancy could be negligible. In the analysis, which assumes one-dimensional processes, the transport equations are solved to give the smolder spread rate as a function of the inlet oxygen mass flux. This mass flux is then estimated by balancing buoyancy and drag forces. Assuming that the smolder chemical reaction is only weakly dependent on pressure, the analysis finally predicts a smolder velocity dependence of the form v Yoig2gi Pa2, i.e. is proportional to the ambient pressure squared. Good qualitative agreement is found between the theoretical predictions and the experimental results. 相似文献