Open AccessStatistical study of effect of solar wind dynamic pressure enhancements on dawn‐to‐dusk ring current asymmetry
Author(s) -
Shi Y.,
Zesta E.,
Lyons L. R.,
Yumoto K.,
Kitamura K.
Publication year - 2006
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 - 10.1029/2005ja011532
Subject(s) - ring current , asymmetry , substorm , noon , earth's magnetic field , solar wind , geomagnetic storm , middle latitudes , physics , current (fluid) , atmospheric sciences , dynamic pressure , local time , environmental science , magnetosphere , magnetic field , mechanics , mathematics , quantum mechanics , thermodynamics , statistics
In this paper, we statistically investigate the effect of solar wind dynamic pressure enhancements on the dawn‐to‐dusk ring current asymmetry by examining disturbances of the ASY‐H index and low‐latitude and midlatitude ground asymmetric perturbations in the north‐south (H) component of the geomagnetic field during 186 events occurring from 1 June 2003 to 30 September 2004. Both storm time and nonstorm time events are included. It is found that a pressure enhancement further intensifies the ring current asymmetry provided that the ring current is already asymmetric at the time of the onset of the pressure enhancement. This effect strongly depends on the IMF B z conditions prior to the pressure enhancement. Generally, for negative IMF B z , pressure enhancements further increase the ring current asymmetry. This effect also depends on the strength of the pressure enhancement. Under the same IMF B z conditions, the stronger the pressure enhancement is, the stronger the intensification of the asymmetric ring current is. The IMF B z conditions during a pressure enhancement play a similar role to that of the IMF B z preconditioning. The results further show that midlatitude H perturbations around the local noon or midnight region as well as the ASY‐H index often include significant contribution from field‐aligned currents, e.g., the region 1 (R1) or region 2 (R2) currents or the substorm current wedge.