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Evolution of IMF B y Induced Asymmetries: The Role of Tail Reconnection
Author(s) -
Ohma A.,
Østgaard N.,
Laundal K. M.,
Reistad J. P.,
Hatch S. M.,
Tenfjord P.
Publication year - 2021
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2021ja029577
Subject(s) - physics , magnetosphere , magnetic reconnection , interplanetary magnetic field , asymmetry , phase (matter) , ionosphere , astrophysics , geophysics , plasma , solar wind , nuclear physics , quantum mechanics
North‐south asymmetries arise in the magnetosphere‐ionosphere system when a significant east‐west ( B y ) component is present in the interplanetary magnetic field (IMF). During such conditions, a B y component with the same sign as the IMF B y component is induced in the magnetosphere, and the locations of conjugate magnetic footpoints are displaced between the two hemispheres. It has been suggested that these asymmetries are introduced into the closed magnetosphere by tail reconnection. However, recent studies instead suggest that asymmetric lobe pressure induces the asymmetries, which are then reduced during periods of enhanced tail reconnection. To address this, we use the Lyon‐Fedder‐Mobarry (LFM) model and initiate a loading‐unloading cycle in multiple runs by changing the IMF. Asymmetries are induced during the loading phase and reduced during the unloading phase. The model results thus suggest that asymmetries arise during periods with low tail reconnection and are reduced during periods with enhanced tail reconnection.