09:05 〜 09:30
[PEM12-02] Convection in the Inner Magnetosphere: Effects on Plasmasphere and Ring Current
★Invited Papers
キーワード：inner magnetosphere、convection、plasmasphere、ring current、erosion、storms
We present two key elements of the effects of inner magnetospheric convection.
The first element is plasmaspheric erosion, a fundamental element of the dynamic magnetospheric response to solar wind driving. We use extreme ultraviolet (EUV) images from the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) mission to examine the relative timing of dayside and nightside plasmapause motion following southward interplanetary magnetic field turnings. For two case studies we find the delay between the dayside and nightside plasmapause response is less than the 10 min temporal resolution of IMAGE EUV, and the time-averaged plasmapause electric (E) field is 9% to 10% of the solar wind E-field. This first result yields important observational constraints on the day-to-night magnetospheric propagation of solar wind energy.
The second element of convection's effects is ring current intensification, widely considered a defining aspect of storms. We use a large database of energetic neutral atom (ENA) images from Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) to examine the statistical response of the ring current to solar wind driving. The database comprises 61 events, including 1838 maps of TWINS-derived equatorial ion flux. We find a strong correlation between solar wind E-field and ring current flux intensification: correlation coefficients are [0.95, 0.94, 0.88] at [1, 16, 30] keV. The strongest solar wind driven convection preferentially increases the least energetic ions. Lower-energy ions are increased farther eastward and higher-energy ions closer to midnight. Enhanced RC ion flux occurs or peaks (on average) at higher L-shells for strong solar wind pressure than for strong convection. This second result confirms and quantifies the high geoeffectiveness of convection.
The first element is plasmaspheric erosion, a fundamental element of the dynamic magnetospheric response to solar wind driving. We use extreme ultraviolet (EUV) images from the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) mission to examine the relative timing of dayside and nightside plasmapause motion following southward interplanetary magnetic field turnings. For two case studies we find the delay between the dayside and nightside plasmapause response is less than the 10 min temporal resolution of IMAGE EUV, and the time-averaged plasmapause electric (E) field is 9% to 10% of the solar wind E-field. This first result yields important observational constraints on the day-to-night magnetospheric propagation of solar wind energy.
The second element of convection's effects is ring current intensification, widely considered a defining aspect of storms. We use a large database of energetic neutral atom (ENA) images from Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) to examine the statistical response of the ring current to solar wind driving. The database comprises 61 events, including 1838 maps of TWINS-derived equatorial ion flux. We find a strong correlation between solar wind E-field and ring current flux intensification: correlation coefficients are [0.95, 0.94, 0.88] at [1, 16, 30] keV. The strongest solar wind driven convection preferentially increases the least energetic ions. Lower-energy ions are increased farther eastward and higher-energy ions closer to midnight. Enhanced RC ion flux occurs or peaks (on average) at higher L-shells for strong solar wind pressure than for strong convection. This second result confirms and quantifies the high geoeffectiveness of convection.