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Asymmetric development of magnetospheric storms during magnetic clouds and sheath regions
Author(s) -
Huttunen K. E. J.,
Koskinen H. E. J.,
Karinen A.,
Mursula K.
Publication year - 2006
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 - 10.1029/2005gl024894
Subject(s) - geomagnetic storm , magnetic cloud , storm , substorm , atmospheric sciences , asymmetry , interplanetary magnetic field , solar wind , interplanetary spaceflight , physics , magnetic field , geophysics , magnetosphere , geology , meteorology , quantum mechanics
This study examines how the asymmetry in the low‐latitude geomagnetic field evolves during sheath and magnetic cloud domains of interplanetary coronal mass ejections using the Dst , SYMH and ASYH indices. For all investigated storms the station that contributed most to Dst was located in the dusk sector while the smallest disturbance field was concentrated around dawn. We found that sheath region storms are associated with larger morning/afternoon asymmetry than magnetic cloud storms. For sheath storms the station in the dusk sector contributed almost four times as much to Dst as the station in the dawn sector. Furthermore, the disturbance field is strongly variable during sheath storms. The results of this study suggest that for magnetic cloud storms the asymmetry arises mainly from ions drifting on open trajectories whereas in a case of a sheath driven storm the sudden intensifications of the substorm associated current systems add significantly to the asymmetry.