National Natural Science Foundation of China [41574157, 41628402, 41774153]
; Shandong University (Weihai) Future Plan for Young Scholar [2017WHWLJH08]
; SNSB grant [77/14]
; STFC [ST/N00722/1]
; NERC [NE/L007495/1, NE/P017150/1, NE/P017185/1]
英文摘要:
The cold-dense plasma sheet (CDPS) plays an important role in the entry process of the solar wind plasma into the magnetosphere. Investigating the seasonal variation of CDPS occurrences will help us better understand the long-term variation of plasma exchange between the solar wind and magnetosphere, but any seasonal variation of CDPS occurrences has not yet been reported in the literature. In this paper, we investigate the seasonal variation of the occurrence rate of CDPS using Geotail data from 1996 to 2015 and find a semiannual variation of the CDPS occurrences. Given the higher probability of solar wind entry under stronger northward interplanetary magnetic field (IMF) conditions, 20 years of IMF data (1996-2015) are used to investigate the seasonal variation of IMF B-z under northward IMF conditions. We find a semiannual variation of IMF B-z, which is consistent with the Russell-McPherron (R-M) effect. We therefore suggest that the semiannual variation of CDPS may be related to the R-M effect.
