A missing dusk-side loss process in the terrestrial electron ring current.

Area of Science:

• Space Physics
• Plasma Physics
• Geophysics

Background:

• The Earth's magnetic field generates a ring current from trapped charged particles.
• Ring current dynamics during geomagnetic storms are complex and not fully understood.
• Existing models show systematic overestimation of electron flux (10-50 keV) on the nightside during storm onset.

Purpose of the Study:

• To identify the cause of systematic overestimation of electron flux in current ring current models.
• To investigate missing loss processes affecting electron flux during geomagnetic storms.
• To improve the accuracy of ring current models.

Main Methods:

• Analysis of electron drift trajectories.
• Comparison of model predictions with satellite observations.
• Quantification of a previously unaccounted-for loss process.

Main Results:

• Existing ring current models overestimate nightside electron flux (10-50 keV) during storm onset.
• A significant electron loss process in the pre-midnight sector is identified.
• This loss process must operate at its theoretical maximum over a broad region to match observations.

Conclusions:

• A crucial electron loss mechanism is missing from current ring current models.
• Inaccuracies in modeling chorus wave interactions and the exclusion of electrostatic electron cyclotron harmonic wave scattering likely contribute to this missing loss.
• Accurate representation of these loss processes is essential for understanding geomagnetic storm dynamics.