О пещерных львятах

The geomagnetic manifestation of sudden impulse (SI) caused by a sharp decrease of the solar wind dynamic pressure due to the plasma density reduction is considered. The observational data of the magnetometer world network have been analysed. The propagation velocities of the SI signal in the meridional direction by using data of the horizontal component of geomagnetic field in the high-latitude region have been calculated. It is found that at a sharp decrease of the solar wind density the meridional propagation of the SI signal is in the northern direction. In this case, on the day side the propagation velocity is constant but there is a tendency of its increasing in the MLT morning sector. It has been established that the meridional propagation velocity of the SI signal at a sharp decrease of the solar wind density depends on the geomagnetic latitude, i.e. with the rise of latitude the velocity in the auroral zone decreases and in the polar cap it increases.

Об учёных Сергее и Никите Зимовых

The 20.11.03 super-storm is described on the basis of the quantitative estimations of input and output parameters of the magnetospheric disturbance energetics. Two input parameters are ε'- Poynting flux from solar wind into the magnetosphere, and the polar cap potential drop Upc. The output parameters (indicators the magnetospheric responses) are the total power of the magnetospheric disturbance (Qt), and the powers consumed in the ionosphere (Qi) and in the ring current (Qdr). Different modes of the magnetosphere disturbances are shortly described: substorms, driven mode, Null Events by Lyons et. al., saturation of the ionosphere, and responses to a strong s. w. pressure pulses. The problem of the substorms-storm relationship is also addressed.

По данным наземных и спутниковых наблюдений рассматриваются квазипериодические изменения геомагнитного поля и параметров плазмы в диапазоне Pc 5 пульсаций, последовавшие сразу после взаимодействия межпланетной ударной волны (МУВ) с земной магнитосферой в событии 24.04.2009 в 00:53 UT. Пульсации были локализованы на широтах 66-74° в полуденном (11 MLT) и вечернем (20 MLT) секторах. Анализ годографов изменений геомагнитного поля как по спутниковым, так и наземным наблюдениям показал наличие вихревых возмущений. В данном событии фронт МУВ в межпланетной среде и фронт волны сжатия в магнитосфере имели наклон в плоскости ZGSM=0, угол наклона составлял 14° в межпланетной среде и 34° в магнитосфере. Положение вихревых возмущений в магнитосфере на разном радиальном расстоянии: X~5.5 Re в полуденном и X~-6.3÷-7.3 Re в вечернем секторе, согласуется с наклоном фронта. По спутниковым наблюдениям максимальная интенсивность волновых возмущений в обоих секторах регистрировалась в тороидальной компоненте, что соответствовало резонансному механизму возбуждения этих возмущений. Анализ распределения скоростей течения плазмы и распространения фронта волны сжатия в магнитосфере показал, что вихревые возмущения наблюдались в областях, где скорости течения плазмы и распространения фронта значительно различались по величине.
Quasi-periodic changes of the geomagnetic field and plasma parameters in the range of Pc 5 pulsations, which occurred immediately after the interaction of interplanetary shock (IPS) with Earth’s magnetosphere in the event of April 24, 2009 at 00:53 UT are examined using ground and satellite observations. The pulsations were localized at latitudes 66-74° in the noon (11 MLT) and evening (20 MLT) sectors. The analysis of hodographs of the geomagnetic field changes both from satellite and ground observations has shown the presence of vortical disturbances. In this event, both the IPS front in the interplanetary medium and the compression wave front in the magnetosphere had a slope in the ZGSM=0 plane; the inclination angle was 14° in the interplanetary medium and 34° in the magnetosphere. The location of the vortical disturbances in the magnetosphere at different radial distances, i.e. X ~5.5 Re in the noon sector and X ~-6.3 ÷-7.3 Re in the evening sector, is in agreement with the front inclination. As inferred from satellite observations, the maximum intensity of wave disturbances in both the sectors was registered in the toroidal component of the magnetic field. This suggests the resonant mechanism of excitation of these disturbances. The analysis of distribution of velocities of plasma flow and compression wave front propagation in the magnetosphere’s equatorial plane has revealed that the vortical disturbances occurred in regions where these velocities were noticeably different in magnitude.