Magnetic Cloud and Its Interplanetary Shock Sheath as a Modulator of the Cosmic Ray Intensity

Journal of Astronomy and Space Sciences

Su Yeon Oh¹ 

[1] Dept. of Astronomy and Space Science, Chungnam University, Daejeon 305-764, Korea ;

关键词: Forbush Decrease;    Cosmic ray;    Magnetic cloud;    Interplanetary shock;   

DOI  :  10.5140/JASS.2008.25.2.149

来源: DOAJ

【 摘 要 】

Forbush Decreases (FDs) are representative events of abrupt decrease in galactic cosmic ray intensity. They are known to be strongly associated with solar wind events such as interplanetary shock (IP shock) and magnetic cloud (MC). In order to examine effectiveness of the MC on FDs, I studied the 44 MCs that occurred during the 2 years from 1998 to 1999 and investigated the properties of interplanetary magnetic field (IMF) and solar wind. As a result, I found that 11 out of 44 MCs are associated with the FDs. In particularly, it is noted that the FDs are driven by the IP shock sheaths which are associated with over 13 nT of IMF magnitude, 3 nT of IMF turbulence, and 550 km/s of solar wind speed. This result indicates that magnetic cloud and its interplanetary shock sheath work as a modulator of the cosmic ray intensity.

【 授权许可】

Unknown