In The Deceleration Of The Earth Shock Precursor Zone. The Solar Wind And The Earth's Inner Magnetosphere Structure Research

In this dissertation, we study, respectively, the solar wind deceleration in the Earth's foreshock region and the structures together with dynamics in the Earth's inner magnetosphere. We divided the dissertation into two parts.In the first part, by analyzing data from the multi-point observation mission CLUSTER, we find for the first time that the solar wind is decelerated when it pass the Earth's foreshock region. The maximum value of the deceleration is determined to be ~22km/s. We notice that in the region of deceleration the temperature of the foreshock ions increases, and the activities of the Ultra-Low Frequency (ULF) waves intensify. The decreased kinetic energy of the solar wind is believed to be transformed into the foreshock ions'thermal energy through the wave-particle interaction between the ULF wave and the solar wind ions. After investigations of the frequency by using Fourier transformation, wave vector by using the wave telescope, polarization by using the Minimum Variance Analysis (MVA), this ULF wave causing the solar wind deceleration is determined to be the Alfvén-whistler mode. This mode has a phase velocity faster than the local Alfvén velocity, a frequency between the Alfvén wave and whistler wave, and a characteristic of right-handed polarization. It exists frequently inside the foreshock region. A statistical study based upon a large amount of CLUSTER date shows that the values of deceleration distributed in the vast foreshock region display the following characteristics: (1) the shorter the distance from the deceleration region to the bow shock (along the magnetic field line), the larger the deceleration; (2) the deceleration is larger when the angle of the magnetic field line threading the deceleration region with respect to the bow shock normal is smaller; (3) the deceleration is most prominent when the distance from the deceleration region to the boundary of the ULF wave activity is within 0-6RE. The relation between the ULF-wave-region and the deceleration also suggests that the ULF wave is a key factor in the process of deceleration. When the solar wind decelerates, it also deflects. The solar wind deflection bears the characteristics similar to those of the soar wind deceleration.In the second part, we analyze the data from IMAGE RPI & EUV, DMSP, ACE, and also the geomagnetic indices recorded on the ground, then focus on some interesting phenomenon and structures occurring inside the inner magnetosphere. We first study the evolution and dynamics of these structures. We reveal that the evolution of the inner magnetosphere from the nightside to the dayside is dominated by the refilling process. In a normal situation, the plasmapause exist clearly in the nightside will also exist in the dayside although it may be relocated outward to some degree. After tracing the drift trajectory of the flux tube from the nightside to the dayside, we find that the"outward motion"of the plasmapause is caused primarily by the refilling from the ionosphere. The refilling process elevates the density in the region just beyond the plasmapause to a level comparable to the plasmasphere. This proposition is also supported by the DMSP observations. In an extreme situation, however, the plasmapause pre-existing in the nightside disappears when it corotates to the dayside. In fact, the plasmapause is not observable to the region of L = 12, indicting that the plasma density in the entire dayside plasmatrough is elevated. After evaluation of the refilling rate, we find in the normal situation the refilling rate is 0.27 cm-3 h-1, in the extreme situation the rate is 0.88 cm-3 h-1. These two refilling rates approach, respectively, the low limit and high limit of the range given in the previous studies, hence should be reasonable. After comparing the flux of the H+ outflow observed by DMSP at the topside ionosphere with the density increase observed by IMAGE in the plasmasphere, we confirm that the outflow flux from the ionosphere is large enough to supply the source of refilling.Secondly we perform a case study on the density trough inside the plasmasphere. When IMAGE flew through the plasmasphere region, a density trough inside the plasmasphere with width ofΔL=0.7 is discovered. This inner density trough is revealed to extend from the IMGAE orbit plane to MLAT~41°along the magnetic field lines according to the field-aligned density profiles derived from the RPI sounding measurement. In the meantime, DMSP observed a low-density region of light ions at the topside ionosphere in a similar MLT sector and L-shell range, indicting the inner density trough indeed extends from the plasmasphere altitude to the ionosphere altitude along the field lines.