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Study on the Curvature and Gradient of the Magnetic Field in Earth's Cusp Region Based on the Magnetic Curvature Analysis Method
Author(s) -
Xiao Chao,
Liu Wenlong,
Shen Chao,
Zhang Hua,
Rong Zhaojin
Publication year - 2018
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2017ja025028
Subject(s) - curvature , magnetic field , physics , cusp (singularity) , interplanetary magnetic field , earth radius , geophysics , radius , computational physics , geodesy , geometry , geology , solar wind , mathematics , magnetosphere , quantum mechanics , computer security , computer science
This paper uses the multiple‐point magnetic measurements from the Cluster mission to investigate the curvature and gradient of the magnetic field as well as their relations with the current density inside the cusp region under different interplanetary magnetic field (IMF) conditions. From two event studies, it is shown that the curvature radius of magnetic field line is on average 5.13 R E under southward IMF and 19.75 R E under northward IMF condition. The directional angle of curvature is more distributed in a wider range under southward condition. The gradient of the magnetic field strength B is larger with a larger standard deviation under southward IMF condition. These results imply that the cusp region has more complicated magnetic structures under southward IMF condition. Through the correlation analysis between the magnetic field parameters and the current density, it is found that the magnetic gradient has a strong relation with total current density j t and perpendicular current density j ⊥ when the ratio of parallel component j // to j t decreases, possibly due to gradient B drift. Furthermore, we present a statistical study on the 19 cusp crossing events from July 2003 to September 2003. The results from the statistical study are consistent with the event studies.