3-d Modeling of Asymmetric Ring Current During Geomagnetic Storms
Abstract
Simulations of the transport of ring current particles in the magnetosphere during disturbances are attempted using a three-dimensional single particle code. The simulations considered, for the magnetospheric field both the dipole and Tsyganenko models and for the convection electric field the model of Volland-Stern with dependent index of Kp=3-8. The energetic protons of several tens of keV start on the night side at L=3-4 and have motion confined to the equatorial plane mostly under gradient magnetospheric drift. However, soon after crossing the noon-night meridian, at some point in their ExB transport trajectory, the protons are observed to abruptly depart from the equatorial plane and move towards high latitude regions. This latter motion is essentially confined to a plane perpendicular to the equator and is characterized by finite periodic motion. The calculations further indicated sudden violation of the first adiabatic invariant at the point of departure from the equatorial region, with slow variation latter along the orbit. The greater the convection electric field the higher is the energy of the protons participating in this off equatorial flow. These numerical calculations indicated that this perpendicular flow can significantly contribute to the morning-evening component of the magnetic field perturbation at storm time, populating the high latitude region by protons with energy around tens of keV. The more energetic ions, however, continue their magnetic drift around the Earth uninterruptedly and form the symmetric ring current population.
- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27..459P