Browsing by Author "Wei, Y."

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    Can a nightside geomagnetic Delta H observed at the equator manifest a penetration electric field?
    (American Geophysical Union, 2013-02-12) Wei, Y.; Fraenz, M.; Dubinin, E.; He, M.; Ren, Z.; Zhao, B.; Liu, J.; Wan, W.; Yumoto, K.; Watari, S.; Alex, S.
    A prompt penetration electric field (PPEF) usually manifests itself in the form of an equatorial ionospheric electric field being in correlation with a solar wind electric field. Due to the strong Cowling conductivity, a PPEF on the dayside can be inferred from Delta H (ΔH), which is the difference in the magnitudes of the horizontal (H) component between a magnetometer at the magnetic equator and one off the equator. This paper aims to investigate the performance of ΔH in response to a PPEF on the nightside, where the Cowling conductivity is not significant. We first examine the strongest geomagnetically active time during the 20 November 2003 superstorm when the Dst drops to −473 nT and show that the nightside ΔH can indeed manifest a PPEF but with local time dependence and longitude dependence. We then examine a moderately active time by taking advantage of the multiple‐penetration event during 11–16 November 2003 when the Dst remains greater than −60 nT. During this event, a series of PPEF pulses recorded in Peru, Japan, and India form a database, allowing us to examine PPEF effects at different local times and longitudes. The results show that (1) the nightside ΔH was caused by attenuation of the effects of the polar electric field with decreasing latitude; (2) the nightside ΔH can manifest a PPEF at least in the midnight‐dawn sector (0000–0500 LT), but not always; and (3) the magnitude of the nightside ΔH in the midnight‐dawn sector in Peru is on average only 1/18 of that of the dayside ΔH in response to a given PPEF.
    Palabras clave:Electric field penetrationSuperstormIonospheric electric field
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    Coordinated observations of magnetospheric reconfiguration during an overshielding event
    (American Geophysical Union, 2008-08-14) Wei, Y.; Hong, M.; Wan, W.; Du, A.; Pu, Z.; Thomsen, M. F.; Ren, Z.; Reeves, G. D.
    During 1400–1800 UT on September 15, 2005, the solar wind exhibited large variations and caused a moderate magnetic storm. The Jicamarca incoherent scatter radar, located near the local noon, observed an overshielding event after the northward turning of interplanetary magnetic field. The overshielding event featured distinct increase and decrease phases. We have examined the magnetospheric configuration variation with the geosynchronous observations provided by GOES12 (dayside) and LANL 97A (nightside), as well as the tail magnetic field monitored by Double Star TC1. The results suggested that the time‐dependent magnetospheric reconfiguration process is closely related to the development of equatorial electric field. We speculate that the magnetospheric reconfiguration may cause equatorial ionosphere electric field disturbances through affecting the Region 2 field aligned current.
    Palabras clave:Magnetospheric reconfigurationOvershieldingRadar