國立中央大學大氣科學學系系友會

講　　題 ： Solar wind driving simultaneous Pc 5 and Pi2 occurrences during a strong northward IMF period  





時    間 ：  2009-03-19 14:00:00  

地    點 ： 科四館S4-917 

講    師 ： 櫻井 亨 教授（Prof. emeritus in Tokai University, 

英文演說 ： 是 

摘要：

We examined a solar wind dynamic pressure impact on the magnetosphere during a trailing period of the magnetic cloud on 8 November 2000 accompanied with the strong northward interplanetary magnetic field (IMF). The study was performed synthetically with the data obtained by many different satellites, globally located ground magnetometers and HF radars in high latitudes. The satellite data were studied by using the ACE and GEOTAIL satellite in the interplanetary space, and the geosynchronous satellites, GOES 8 and 10, LANL1994, and LANL1989, and POLAR satellite in the night-side magnetosphere. The ground data are the global ground magnetometer data from the northern polar region to the magnetic equator covering the extending longitudes from the day to the night, and the SuperDARN HF radar data from high latitude stations.

The results are as follows: Three different typical ULF waves were observed. One is a long period Pc 5 oscillation with a period of approximate10 minutes. This oscillation was globally observed on the ground and in the magnetosphere, concurrent to the solar wind dynamic pressure variations, and showed a DP-2 like global oscillation in the magnetosphere, and the others were shorter period Pc 5 and Pi 2 oscillations with a period of approximate 3 and 5 minutes. They occurred simultaneously in the dawn side and the night-side auroral latitudes. The Pi 2 oscillation was observed with an auroral brightening in the midnight sector. These three-type oscillations were observed in association with a simultaneous appearance of enhanced plasma convection shear flow observed in the dawn-side and the night-side high-latitude ionosphere, suggesting that the generation of these phenomena is directly driven by penetration of large-scale electric field associated with the field-aligned current induced by the impact of the solar wind dynamic pressure pulse. The longer period oscillation was observed with a close relationship to the periodic appearance of plasma flows in the high-latitude ionosphere, and showed a DP-2 like global oscillation in the magnetosphere. While the shorter period Pc 5 and Pi 2 oscillation appeared restrictively in the aurora latitudes and in the longitudes, suggesting a field-line resonance oscillation (FLR). Although the generation was different each other, they were directly driven by impact of a solar wind dynamic pressure impact and implies that the solar wind dynamic pulse can play an important role to the solar wind- magnetosphere - ionosphere coupling even in a strong northward IMF period.