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1.
Kleimenova N. G. Gromova L. I. Gromov S. V. Malysheva L. M. 《Geomagnetism and Aeronomy》2021,61(4):520-530
Geomagnetism and Aeronomy - The features of the geomagnetic effect of the approach of an interplanetary magnetic cloud to the Earth’s magnetosphere during the recovery phase of a strong... 相似文献
2.
This study considers the possibility of using the new methods of time-frequency transforms, such as chirplet and warblet transforms, to analyze the digital observational data of geomagnetic pulsations of Pc5 type. For this purpose, necessary algorithms of calculation and appropriate software were developed. The chirplet transform method (CT) is used to analyze signals with a linear frequency modulation. A chirplet variation, the so-called warblet transform, is used to analyze signals with a nonlinear frequency modulation. Since, in studying geomagnetic pulsations, it is difficult to make assumptions on the character of the behavior of the instantaneous frequency of the signal, the special generalized warblet transform (GWT) was used for the analysis. The GWT has a high spatiotemporal resolution and was developed to analyze oscillations both with a periodic and nonperiodic change of the instantaneous frequency. The software developed for GWT calculation was used to study daytime geomagnetic Pc5 pulsations with durations of several hours that were detected via the network of ground-based magnetometers of the Scandinavian IMAGE profile during the magnetic storm of May 29–30, 2003. For the first time, temporal variations of the instantaneous frequency of geomagnetic pulsations are determined and their possible use in studying the fine spatial structure of Pc5 waves is shown. 相似文献
3.
L. I. Gromova N. G. Kleimenova A. E. Levitin S. V. Gromov L. A. Dremukhina N. R. Zelinskii 《Geomagnetism and Aeronomy》2016,56(3):281-292
The high-latitude geomagnetic effects of an unusually long initial phase of the largest magnetic storm (SymH ~–220 nT) in cycle 24 of the solar activity are considered. Three interplanetary shocks characterized by considerable solar wind density jumps (up to 50–60 cm–3) at a low solar wind velocity (350–400 km/s) approached the Earth’s magnetosphere during the storm initial phase. The first two dynamic impacts did not result in the development of a magnetic storm, since the IMF Bz remained positive for a long time after these shocks, but they caused daytime polar substorms (magnetic bays) near the boundary between the closed and open magnetosphere. The magnetic field vector diagrams at high latitudes and the behaviour of high-latitude long-period geomagnetic pulsations (ipcl and vlp) made it possible to specify the dynamics of this boundary position. The spatiotemporal features of daytime polar substorms (the dayside polar electrojet, PE) caused by sudden changes in the solar wind dynamic pressure are discussed in detail, and the singularities of ionospheric convection in the polar cap are considered. It has been shown that the main phase of this two-stage storm started rapidly developing only when the third most intense shock approached the Earth against a background of large negative IMF Bz values (to–39 nT). It was concluded that the dynamics of convective vortices and the related restructing of the field-aligned currents can result in spatiotemporal fluctuations in the closing ionospheric currents that are registered on the Earth’s surface as bay-like magnetic disturbances. 相似文献
4.
A. E. Levitin L. I. Gromova S. V. Gromov L. A. Dremukhina 《Geomagnetism and Aeronomy》2014,54(3):292-299
A new method for determining geomagnetic activity based on calculation of the hourly amplitudes of geomagnetic field variations at ground-based observatories has been developed. Observations performed in 2009, when unusually low solar and geomagnetic activity was registered, were used as a reference level. The described method was used to estimate the energy of local geomagnetic activity; such energy is estimated for observatories in the Earth’s Northern and Southern hemispheres, and a total estimation is made for both hemispheres and for the entire Earth’s surface during large magnetic storms. These are used to compare characteristics of magnetic storm intensity based on the classical Kp and Dst indices and calculated energy estimate. 相似文献
5.
M. Förster Y. I. Feldstein L. I. Gromova L. A. Dremukhina A. E. Levitin S. E. Haaland 《Geomagnetism and Aeronomy》2013,53(1):85-95
Measurements onboard Cluster satellites are briefly described, which form the base for determining the intensity and direction of the electric field in the magnetosphere. The aim of this paper is to describe (1) the methodology of calculating the potential distribution at the ionospheric level and the results of constructing spatiotemporal convection patterns for different orientations of the IMF vector in the GSM YZ plane; (2) derivation of basic convection patterns (BCPs), which allow to deduce the statistical ionospheric convection pattern at high latitudes for any IMF Bz and By values (statistical convection model) using different sets of independent data; (3) the consequences of enlarging the amount of data used for analysis; (4) the results of potential calculations with various orders of the spherical harmonics describing them; (5) determination of the cross-polar cap potential with different IMF sector widths (α from 45° down to 10°); (6) the results of our trials to determine the contribution of the IMF Bx component to the convection pattern. 相似文献
6.
M. N. Gromova 《Water Resources》2008,35(5):605-608
Field data are used to assess the autocorrelation coefficient between successive terms in the series of minimal 30-day sums of river runoff in the winter and summer-autumn low-flow periods in the Russian territory. Zoning of the autocorrelation coefficient of winter and summer-autumn runoff is carried out within this territory, and the character of its dependence on the module and coefficient of variation of minimal runoff is studied. 相似文献
7.
A. D. Shevnin A. E. Levitin L. I. Gromova L. A. Dremukhina L. N. Kaynara 《Geomagnetism and Aeronomy》2009,49(3):297-302
The data of Moscow observatory for the 1946-2006 interval of observations are analyzed in order to detect long-term geomagnetic variations related to solar activity against a background of the secular variations in the geomagnetic field. 相似文献
8.
N. A. Barkhatov L. I. Gromova A. E. Levitin S. E. Revunov 《Geomagnetism and Aeronomy》2008,48(6):713-718
The relation of the Kp index of geomagnetic activity to the solar wind electric field (E SW) and the projection of this field onto the geomagnetic dipole has been estimated. An analysis indicated that the southward component of the IMF vector (B z < 0) is the main geoeffective parameter, as was repeatedly indicated by many researchers. The presence of this component in any combinations of the interplanetary medium parameters is responsible for a high correlation between such combinations and geomagnetic activity referred to by the authors of different studies. Precisely this field component also plays the main role in the relation between the Kp index and the relative orientation of E SW and the Earth’ magnetic moment. 相似文献
9.
Despirak I. V. Kleimenova N. G. Gromova L. I. Gromov S. V. Malysheva L. M. 《Geomagnetism and Aeronomy》2020,60(3):292-300
Geomagnetism and Aeronomy - The development of two supersubstorms (i.e., very intense substorms with an amplitude of more than 2000 nT) recorded in the main phase of two consecutive strong magnetic... 相似文献
10.
A. E. Levitin L. I. Gromova L. A. Dremukhina N. A. Pal’shin 《Geomagnetism and Aeronomy》2007,47(3):330-335
Based on the model of large-scale high-latitude current systems developed at IZMIRAN (IZMEM model), it has been indicated that auroral electrojets and current systems concentrated in the polar cap were the generators of long-period geomagnetic variations during the BEAR experiment on the electromagnetic field registration at the Scandinavian test site on June 1–July 15, 1998. Precisely circumpolar current systems, prevailing in the high-latitude ionosphere during the periods of a quiet magnetospheric state, which is characterized by the presence of the northern vertical (B z >0) component of the IMF vector in the solar wind, are responsible for the magnetotelluric fields. 相似文献