Investigating the Impact of Field‐Aligned Potential Drops on Auroral Energy Flux and Conductance: Insights From RCM‐I and RCM‐E Simulations

Abstract

The effects of field‐aligned potential drops (FAPDs) on magnetosphere‐ionosphere (M–I) coupling are investigated under steady external driving, while allowing a time‐dependent bubble injection using the generalized Knight relation to convert field‐aligned currents to FAPDs. High‐resolution simulations with the Rice Convection Model‐Equilibrium and Rice Convection Model‐Inertialized reveal FAPDs' impact on auroral substorm characteristics. Including FAPDs, relative to the no‐FAPD case, intensifies the magnetospheric electric field reversal near upward Birkeland currents, accelerating charged particles to precipitate into the ionosphere, forming a streamer‐arc sequence. FAPDs enhance energy flux and ionospheric Pedersen conductivity, particularly when low‐entropy depleted channels (i.e., bubbles) are present, as they reduce plasma density and intensify electric fields. Simulations with FAPDs show greater Pedersen conductivity enhancements than those without FAPDs, especially with bubbles, due to increased electron precipitation. These findings confirm FAPDs' role in boosting precipitating particle energy and decreasing the Pedersen‐to‐Hall conductance ratio, highlighting their significance in M–I dynamics.