We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Modulation of Magnetospheric Substorm Frequency: Dipole Tilt and IMF B<sub>y</sub> Effects.
- Authors
Ohma, A.; Reistad, J. P.; Hatch, S. M.
- Abstract
Substorm activity is heavily influenced by the Interplanetary Magnetic Field (IMF) Bz component and magnetospheric substorms occur most frequently when Bz is strongly negative. The substorm occurrence rate is also affected by the magnitude of the By component, but it is usually presumed that this contribution is independent of the sign of By. Using five independent substorm onset lists, we show that substorm activity does depend on the sign of By near the solstices. Specifically, we show that substorms occur more frequently when By and the dipole tilt angle Ψ have different signs as opposed to when they have the same sign. These results confirm that the magnetosphere exhibits an explicit dependence on the polarity of By for nonzero Ψ, as other recent studies have suggested, and imply variation in the dayside reconnection rate and/or the magnetotail response. On the other hand, we find no clear relationship between substorm intensity and By regardless of Ψ. Last, for the onset list based on identifying negative bays at auroral latitudes, we observe an overall trend of more frequent onsets for positive By, regardless of season. However, substorm frequency in the other four substorm lists does not exhibit an overall preference for positive By. We show that this phenomenon is very likely a consequence of the particular substorm identification method (i.e., identification of negative bays), which is affected by local ionospheric conditions that depend on By and Ψ.
- Subjects
MAGNETIC storms; INTERPLANETARY magnetic fields; MAGNETOSPHERIC substorms; MAGNETOSPHERE; MAGNETOTAILS
- Publication
Journal of Geophysical Research. Space Physics, 2021, Vol 126, Issue 3, p1
- ISSN
2169-9380
- Publication type
Article
- DOI
10.1029/2020JA028856