Open AccessRing current dynamics in moderate and strong storms: Comparative analysis of TWINS and IMAGE/HENA data with the Comprehensive Ring Current Model
Author(s) -
Buzulukova N.,
Fok M.C.,
Goldstein J.,
Valek P.,
McComas D. J.,
Brandt P. C.
Publication year - 2010
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2010ja015292
Subject(s) - ring current , physics , storm , current (fluid) , van allen probes , ring (chemistry) , astrophysics , atmospheric sciences , meteorology , van allen radiation belt , magnetosphere , nuclear physics , plasma , chemistry , organic chemistry , thermodynamics
We present a comparative study of ring current dynamics during strong and moderate storms. The ring current during the strong storm is studied with IMAGE/HENA data near the solar cycle maximum in 2000. The ring current during the moderate storm is studied using energetic neutral atom (ENA) data from the Two Wide‐Angle Imaging Neutral‐Atom Spectrometers (TWINS) mission during the solar minimum in 2008. For both storms, the local time distributions of ENA emissions show signatures of postmidnight enhancement (PME) during the main phases. To model the ring current and ENA emissions, we use the Comprehensive Ring Current Model (CRCM). CRCM results show that the main‐phase ring current pressure peaks in the premidnight‐dusk sector, while the most intense CRCM‐simulated ENA emissions show PME signatures. We analyze two factors to explain this difference: the dependence of charge‐exchange cross section on energy and pitch angle distributions of ring current. We find that the IMF B y effect (twisting of the convection pattern due to B y ) is not needed to form the PME. Additionally, the PME is more pronounced for the strong storm, although relative shielding and hence electric field skewing is well developed for both events.