Magnetospheric response of two types in PSc geomagnetic pulsations to interaction with interplanetary shock waves

Using the June 22, 2015 event as an example, we present new data confirming the presence of a precursor of the sudden magnetic impulse caused by a powerful interplanetary shock wave (ISW). The precursor in the form of a train of oscillations (broadband pulse) with a falling frequency in the range 0.25÷11 Hz with a duration of ~20 s, which had a spectral resonance structure, was recorded globally by a network of induction magnetometers at 18:33:27 UT. No significant phase delays of the signals were detected in four frequency bands at widely spaced observatories. It is suggested that the impulse can be excited in the Earth – ionosphere waveguide by a pulsed electric field which occurs in the ionosphere due to the short-term impact of ISW on the magnetosphere

Sharp changes of solar wind ion flux and density within and outside current sheets

Analysis of the Interball-1 spacecraft data (1995-2000) has shown that the solar wind ion flux sometimes increases or decreases abruptly by more than 20% over a time period of several seconds or minutes. Typically, the amplitude of such sharp changes in the solar wind ion flux (SCIFs) is larger than 0.5x10^8 cm^-2 s^-1. These sudden changes of the ion flux were also observed by the Solar Wind Experiment (SWE), on board the WIND spacecraft, as the solar wind density increases and decreases with negligible changes in the solar wind velocity. SCIFs occur irregularly at 1 AU, when plasma flows with specific properties come to the Earth's orbit. SCIFs are usually observed in slow, turbulent solar wind with increased density and interplanetary magnetic field strength. The number of times SCIFs occur during a day is simulated using the solar wind density, magnetic field, and their standard deviations as input parameters for a period of 5 years. A correlation coefficient of ~0.7 is obtained between the modelled and the experimental data. It is found that SCIFs are not associated with coronal mass ejections (CMEs), corotating interaction regions (CIRs), or interplanetary shocks; however, 85% of the sector boundaries are surrounded by SCIFs. The properties of the solar wind plasma for days with 5 or more SCIF observations are the same as those of the solar wind plasma at the sector boundaries. One possible explanation for the occurrence of SCIFs (near sector boundaries) is magnetic reconnection at the heliospheric current sheet or local current sheets. Other probable causes of SCIFs (inside sectors) are turbulent processes in the slow solar wind and at the crossings of flux tubes.Comment: 33 pages, 8 figures, 6 tables, Solar Physics 2011, in pres

Features of the impact of the solar wind diamagnetic structure on Earth’s magnetosphere

In Earth’s orbit on June 28, 1999, there was a diamagnetic structure (DS) representing a filament with a uniquely high speed (about 900 km/s). We show that the filament is a part of the specific sporadic solar wind (SW) stream, which is characterized as a small interplanetary transient. We report the results of studies on the interaction between such a fast filament (DS) and Earth’s magnetosphere. Around noon hours at daytime cusp latitudes, we recorded a powerful aurora in the UV band (shock aurora), which rapidly spread to the west and east. Ground-based observations of geomagnetic field variations, auroral absorption, and auroras on the midnight meridian have shown the development of a powerful substorm-like disturbance (SLD) (AE~1000 nT), whose origin is associated with the impact of the SW diamagnetic structure on the magnetosphere. The geostationary satellite GOES-8, which was in the midnight sector of the outer quasi-capture region during SLD, recorded variations of the Bz and Bx geomagnetic components corresponding to the dipolization process