천문학회보 (The Bulletin of The Korean Astronomical Society)
- 제37권2호
- /
- Pages.115.2-115.2
- /
- 2012
- /
- 1226-2692(pISSN)
Observation of long-term disappearance and reappearance of the outer radiation belt
- 이대영 (충북대) ;
- 신대규 (충북대) ;
- 김경찬 (천문연) ;
- 김진희 (충북대) ;
- 조정희 (충북대) ;
- 박미영 (충북대) ;
- ;
- 황정아 (천문연) ;
- 이용희 (충북대) ;
- 김경호 (충북대)
- Lee, Dae-Young (Astronomy & Space Sci, Chungbuk Natl Univ.) ;
- Shin, Dae-Kyu (Astronomy & Space Sci, Chungbuk Natl Univ.) ;
- Kim, Kyung-Chan (KASI) ;
- Kim, Jin-Hee (Astronomy & Space Sci, Chungbuk Natl Univ.) ;
- Cho, Jung-Hee (Astronomy & Space Sci, Chungbuk Natl Univ.) ;
- Park, Mi Young (Astronomy & Space Sci, Chungbuk Natl Univ.) ;
- Angelopoulos, Vassilis (UCLA) ;
- Hwang, Junga (KASI) ;
- Lee, Yonghee (Astronomy & Space Sci, Chungbuk Natl Univ.) ;
- Kim, Thomas (Astronomy & Space Sci, Chungbuk Natl Univ.)
- 발행 : 2012.10.17
초록
In this study we have used the data of various instruments onboard the THEMIS spacecraft to study the characteristics of the outer radiation belt during the ascending phase of solar cycle 24. The most astonishing result is that we discovered four long-term (a month or so) periods during which the belt has nearly disappeared. The first disappearance started late 2008, followed by reappearance in ~a month, and three more similar events repeated until early 2010 when the belt has reappeared. This is well revealed at 719 keV electrons, which is the currently available uppermost energy channel from the THEMIS SST observation, but also seen at even lower energies. Overall consistent features were confirmed using the NOAA-POES observations. The vanished belt periods are associated with extremely weak solar wind conditions, low geomagnetic disturbances (in terms of Kp and AE/AL), greatly suppressed wave (ULF and chorus) activities, greatly reduced storm and substorm activities (little source particle supply), and expanded plasmapause locations. The direct observations of such events shed light on the fundamental question of the origin of the radiation belt, which is the main focus of our presentation.
키워드