한국우주과학회:학술대회논문집(한국우주과학회보) (Bulletin of the Korean Space Science Society)
- 한국우주과학회 2010년도 한국우주과학회보 제19권1호
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- Pages.40.2-40.2
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- 2010
Morning-afternoon asymmetry of geosynchronous magnetic field variations during geomagnetic sudden commencements
- Park, Jong-Sun (School of Space Research, Kyung Hee University) ;
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Kim, Khan-Hyuk
(School of Space Research, Kyung Hee University) ;
- Sung, Suk-Kyung (School of Space Research, Kyung Hee University) ;
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Lee, Dong-Hun
(School of Space Research, Kyung Hee University)
- 발행 : 2010.04.15
초록
It has been reported that geosynchronous magnetopause crossings are more frequently observed in the prenoon sector than in the postnoon sector, indicating a dawn-dusk magnetopause asymmetry during extreme solar wind conditions. Motivated by these observations, we investigate geosynchronous magnetic field variations normalized to SYM-H when sudden commencements (SC) are observed on the ground. From a statistical analysis of the geosynchronous magnetic field responses to SC events from 1997 to 2006, we found that the normalized SC amplitude at geosynchronous orbit is larger in the morning sector than in the afternoon sector. In order to examine if this morning-afternoon asymmetry at geosynchronous orbit occurs only during disturbed geomagnetic conditions, we compared the geosynchronous magnetic field strength obtained in the morning and afternoon during undisturbed intervals (Kp < 3). We found that the asymmetry appears under undisturbed geomagnetic conditions and it is not due to solar wind aberration. This indicates that the morning-afternoon asymmetry was not strongly affected by changes in solar wind condition. Using solar wind data, we discuss what causes the morning-afternoon asymmetry at geosynchronous orbit.
키워드