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1.
The dynamics of the magnetospheric magnetic field during the magnetic storms of different intensity has been studied. The magnetic field variations on the Earth’s surface were calculated using the paraboloid model of the magnetosphere, taking into account the induction currents flowing in the diamagnetically conductive Earth. Dst and its components have been calculated for ten magnetic storms. It has been indicated that relative contributions of magnetospheric sources to Dst change depending on the storm power. For weak and moderate storms, the contribution of the magnetotail current sheet can reach values comparable with the ring current contribution and, sometimes, can even exceed this contribution. For strong storms, the ring current field dominates over the tail current field, the absolute value of which does not exceed 150 nT (also achieved during less intense storms). For storms with minimum Dst exceeding-200 nT, the tail current field is saturated, whereas the ring current can continue developing. 相似文献
2.
We present a new model of the jovian magnetosphere in which the flaring of the magnetopause boundary can be varied. Magnetopause flaring is expected to vary due to changing conditions in the upstream interplanetary medium, related both to the dynamic pressure of the solar wind, and to changes in the direction of the interplanetary magnetic field. The model includes a tilted dipole field, which is screened by the magnetopause, a tail field current system, and the field of a screened equatorial current disc. 相似文献
3.
地球辐射带中有"杀手"电子之称的相对论电子通量增强和损失过程一直是空间物理学和空间天气学研究的热点.本文通过对20002016年间,地球同步轨道相对论电子通量降低至背景通量水平并持续时间长达3天以上这一特殊现象进行了相关统计研究.从事件的时间分布角度,本文研究了约1.5个太阳活动周内共62例事件随太阳活动水平高低的分布情况,结果表明:在太阳活动周下降期有较少的事件发生,而在峰年、谷年这类事件的发生率与太阳活动水平的高低并没有直接联系.随后,我们对这62例事件在开始、持续、结束三个阶段分别做了一些相关参数的统计,探讨相对论电子通量长期倒空事件的客观规律和产生机制.研究结果表明:事件发生前,太阳风动压、密度的显著增加引起磁层顶向内收缩,等离子体层顶一直维持在高L区域,IMF Bz分量南向和磁暴过程使相对论电子通量通过绝热和非绝热等物理损失机制降至背景通量水平.当这些相对论电子达到背景通量水平后,较弱的太阳风条件和地磁活动水平不足以提供充分的可以使相对论电子通量增长的源;虽然有些相对论电子通量长期倒空事件期间存在中、小磁暴过程,但这些强度较弱的磁暴很可能不会显著地影响同步轨道相对论电子损失和增长的动态平衡,因此相对论电子仍然可以维持在背景通量水平.如果有长时间的亚暴活动和高强度的ULF (Ultra-Low Frequency)波活动发生,太阳风速度显著增加,那么这些物理过程能提供足够的种子电子和持续的加速条件,使得相对论电子通量打破倒空状态,进而呈现显著增长趋势. 相似文献
4.
The mathematical model of the magnetic field of the partial ring current has been proposed. This current is considered as a pair of spatial current circuits in the Northern and Southern hemispheres, either of which includes two ring zones, in the geomagnetic equator plane and ionosphere, and two zones of the field-aligned current, flowing along the geomagnetic dipole field lines and joining ring fragments of the circuit. The model parameters are: colatitude of the eastward electrojet, longitudinal shift relative to the Sun-Earth axis, circuit half-angle, and the total current flowing in the circuit. The Biot-Savart-Laplace law has been used to calculate the magnetic field of the current circuit. The magnetic field of the partial ring current has been calculated under the conditions typical of a strong magnetic storm. The technique for calculating the partial ring current intensity, using the Asym-H geomagnetic index, has been proposed. 相似文献
5.
The results of studying the intensity of fluxes of 30–80 keV ions from the data of measurements of the NOAA (POES) sun-synchronous satellites during geomagnetic storms of different intensity are presented. For 15 geomagnetic storms with |Dst|max from ~37 to ~422 nT, the storm-time maximum ion fluxes in the near-equatorial region (trapped particles) and at high latitudes (precipitating particles) have been considered. It is shown that the maximum fluxes of trapped particles, which are considered a ring-current proxy, increase with the storm power. In this case, if a smooth growth of fluxes is recorded for storms with |Dst|max < 250 nT in the near-equatorial region, a significantly steeper growth of fluxes of trapped particles is observed when storm power increases during storms with |Dst|max > 250 nT. This may be evidence of both an increasing of the contribution of the ring current relative to magnetotail currents to the development of high-intensity storms and to a nonlinear link between the ring current and ion fluxes at low altitudes in the near-equatorial region. Despite large variations in fluxes of precipitating particles in the polar region above the boundary of isotropization, a decreasing tendency, as a whole, in fluxes of these particles is observed with increasing the storm intensity. This is the evidence of the effect of saturation of magnetotail currents and of an increase in the relative role of the ring current during strong magnetic storms. 相似文献
6.
V. V. Kalegaev I. I. Alexeev E. V. Makarenkov N. Yu. Ganvushkina 《Geomagnetism and Aeronomy》2006,46(5):563-569
A unified method for calculating the Dst index and its components using models of the magnetospheric magnetic field is proposed. The method is consistent with the procedure for calculating Dst from the ground-based magnetometer data. When calculating Dst, the quiet-day magnetic variation is subtracted from the model variation of the magnetic field of magnetospheric sources. The effect of induced currents flowing in the surface layer of the Earth’s crust is taken into account. The dynamics of the magnetospheric current systems during a storm is studied based on an analysis of the Dst components. The magnetic field components for a “quiet” day in June 1998 are studied. The calculations of the Dst components in the parabolid and T01 models demonstrate that the maximum contributions of the ring current and magnetotail current system to the Dst variation are comparable for the magnetic storm of June 25–26, 1998. 相似文献
7.
V. V. Kalegaev K. Yu. Bakhmina I. I. Alexeev E. S. Belenkaya Ya. I. Feldstein N. V. Ganushkina 《Geomagnetism and Aeronomy》2008,48(6):747-758
The ring current dynamics during the magnetic storm has been studied in the work. The response of the magnetospheric current systems to the external influence of the solar wind, specifically, resulting in the development of the asymmetric ring current component, has been calculated using the magnetic field paraboloid model. The asymmetric ring current has been considered as a family of spatial current circuits in the Northern and Southern hemispheres, composed of the zones of the partial ring current in the geomagnetic equator plane, which close through the system of field-aligned currents into the ionosphere. The value of the total partial ring current has been estimated by comparing the calculated asymmetry of the magnetospheric magnetic field at the geomagnetic equator with the value of the Asym-H geomagnetic index. The variations in the symmetric and asymmetric components of the ring current magnetic field have been calculated for the magnetic storm of November 6–14, 2004. The contributions of the magnetospheric current systems to the Dst and AU geomagnetic indices have been calculated. 相似文献
8.
Myagkova I. N. Shirokii V. R. Kalegaev V. V. Barinov O. G. Dolenko S. A. 《Geomagnetism and Aeronomy》2021,61(1):138-147
Geomagnetism and Aeronomy - The possible use of artificial neural networks—classical multilayer perceptrons—with coupling functions to forecast time series of the Dst geomagnetic index... 相似文献
9.
Y. I. Feldstein L. I. Gromova A. Grafe C.-I. Meng V. V. Kalegaev I. I. Alexeev Y. P. Sumaruk 《Annales Geophysicae》1999,17(4):497-507
Effect of the equatorward shift of the eastward and westward electrojets during magnetic storms main phase is analyzed based on the meridional chains of magnetic observatories EISCAT and IMAGE and several Russian observatories (geomagnetic longitude ≈110°, corrected geomagnetic latitudes 74°>φ>51°.) Magnetic storms of various Dst index intensity where the main phase falls on 1000 UT - 2400 UT interval were selected so that one of the observatory chains was located in the afternoon - near midnight sector of MLT. The eastward electrojet center shifts equatorward with Dst intensity increase: when Dst ≈ −50 nT the electrojet center is located at φ ≈ 62°, when Dst ≈ −300 nT it is placed at φ ≈ 54°. The westward electrojet center during magnetic storms main phase for intervals between substorms shifts equatorward with Dst increase: at φ ≈ 62° when Dst ≈ −100 nT and at φ ≈ 55° when Dst ≈ −300 nT. During substorms within the magnetic storms intervals the westward electrojet widens poleward covering latitudes φ ≈ 64°–65°. DMSP (F08, F10 and F11) satellite observations of auroral energy plasma precipitations at upper atmosphere altitudes were used to determine precipitation region structure and location of boundaries of various plasma domains during magnetic storms on May 10–11, 1992, February 5–7 and February 21–22, 1994. Interrelationships between center location, poleward and equatorward boundaries of electrojets and characteristic plasma regions are discussed. The electrojet center, poleward and equatorward boundaries along the magnetic observatories meridional chain were mapped to the magnetosphere using the geomagnetic field paraboloid model. The location of auroral energy oxygen ion regions in the night and evening magnetosphere is determined. Considerations are presented on the mechanism causing the appearance in the inner magnetosphere during active intervals of magnetic storms of ions with energy of tens KeV. In the framework of the magnetospheric magnetic field paraboloid model the influence of the ring current and magnetospheric tail plasma sheet currents on large-scale magnetosphere structure is considered. 相似文献
10.
Petrov V. L. Bogomolov A. V. Bogomolov V. V. Kalegaev V. V. Panasyuk M. I. Svertilov S. I. Kosenko A. A. 《Geomagnetism and Aeronomy》2020,60(2):151-161
Geomagnetism and Aeronomy - The spatial distribution and dynamics of subrelativistic electron fluxes (from tens to hundreds of keV) were studied in a space experiment onboard the Vernov satellite.... 相似文献