Prompt Response Of Inner Magnetospheric Plasma Waves To Solar Wind Dynamic Pressure Pulses

Wave-particle interaction is an important physical process controlling the inner magnetospheric environment.Information about the generation mechanism and spa-tiotemporal distribution of the related plasma waves is required to understand and fore-cast the inner magneto spheric particle dynamics.In early studies,solar wind distur-bances have long been recognized to drive the ultra low frequency pulsations.In con-trast,for the extremely low frequency and very low frequency plasma waves,the im-portance of magnetospheric substorm activities is commonly known while the direct contribution of solar wind is rarely reported.Since September 2012,the RBSP mission launched by NASA has provided comprehensive measurements of particles and waves in the inner magnetosphere.The new RBSP data,together with the long term data from the magnetospheric and interplanetary missions(e.g.,THEMIS,ACE,and WIND),al-low a systematic investigation of the dependence of magnetospheric plasma waves on the solar wind.On the basis of data analysis,numerical simulation,and theoretical derivation,we analyze the prompt responses of inner magnetospheric plasma waves to the solar wind dynamic pressure pulses systematically.The research in this thesis involves chorus,plasmaspheric hiss,exohiss,magnetosonic emission,and ultra low frequency pulsation.They cover the frequency range from mHz to several kHz and contribute significantly to the acceleration and loss of the Van Allen radiation belt electrons.Our major find-ings are summarized as follows:(1)the positive solar wind dynamic pressure pulse can reduce the occurrence region of chorus through the magnetopause shadowing and then cause the prompt disappearance of plasmaspheric hiss;(2)the negative solar wind dy-namic pressure pulse can increase the background magnetic field inhomogeneity,sup-press the nonlinear growth of chorus,and then cause the prompt disappearances of plas-maspheric hiss and exohiss;(3)the positive/negative solar wind dynamic pressure pulse can compress/relax the dayside magnetosphere,adiabatically accelerate/decelerate the ring current ions,and then produce the prompt emergence/disappearance of magne-tosonic waves;(4)the solar wind dynamic pressure pulse can excite the ultra low fre-quency pulsations,modulate the background magnetic field configuration and the hot ion distribution,and then yield the quasi-periodic chorus,exohiss,and magnetosonic waves.Our studies demonstrate the importance of solar wind dynamic pressure pulse in the spatiotemporal distribution of magnetospheric plasma waves,and provide a new opportunity to examine the wave generation mechanisms(e.g.,the nonlinear growth mechanism of chorus,correlations between chorus,plasmaspheric hiss and exohiss,the Bernstein instability of magnetosonic emissions and the quasi-periodic relaxation oscillation of plasma instabilities).