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Nonlinear Response of the Cross Polar Cap Potential to Solar Wind Density Under Northward Interplanetary Magnetic Field
Author(s) -
Yang Ziyi,
Zhang Binzheng,
Lei Jiuhou,
Dang Tong
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl087559
Subject(s) - physics , interplanetary magnetic field , solar wind , magnetosheath , polar , magnetosphere , interplanetary spaceflight , ionosphere , magnitude (astronomy) , geophysics , magnetic reconnection , magnetic field , computational physics , magnetopause , atmospheric sciences , astrophysics , astronomy , quantum mechanics
It is commonly believed that the magnitude and orientation of interplanetary magnetic field (IMF) together with the solar wind (SW) velocity have the most important impact on the cross polar cap potential ( φ p c ), so that little attention has been given to the effect of SW density, especially under northward IMF conditions. Previous studies have shown that φ p c increases with SW density as a response to the changes in magnetosheath force balance, while our study shows that φ p c has more complicated responses to the SW density depending on the magnitude of IMF rather than a simple linear response as reported previously. The φ p c may be insensitive to SW density increasing at moderate IMF B z (cf. 8 nT) and at intense B z (20 nT) under large‐density conditions. The different behavior of SW density in regulating φ p c is mainly due to the competing effects originated from viscous interaction and magnetic reconnection. Further, the physical mechanisms are explored, including the driving sources of the viscous potential and affecting factors of reconnection potential. These results pave the way for better understanding of the SW density effects on solar wind‐magnetosphere‐ionosphere (SW‐M‐I) interactions.