Abstract Observations of neutral structuring in the cusp region have been obtained in several satellite and rocket missions. Observations include altitude‐dependent neutral density enhancements (CHAllenging Minisatellite Payload and Gravity Recovery And Climate Experiment satellites) and slight neutral density depletion at lower altitudes (Streak satellite and Rocket Experiment for Neutral Upwelling 2 (RENU2) mission). Soft electron precipitation (< a few hundred eV), ion upwelling, and ion‐neutral momentum exchange are among the processes theorized to drive neutral enhancement. We investigate these processes as they relate to neutral structuring using a high‐resolution ionosphere‐thermosphere numerical model (Alfvén wave scale) that includes inertial ion and neutral terms. A detailed study of a soft electron precipitation event is performed, and the resulting thermospheric response is assessed. Ion‐neutral coupling is found to span vertically for hundreds of kilometers for 15–20 min, enhancing the neutral density at higher altitudes. A slight depletion is found near the F region, driven by divergent ion flow near the region of the most intense electron heating. Temporal effects include an upward traveling compression wave and high‐altitude gravity waves. Thermospheric structuring occurs on a 10‐min time scale.
Sadler et al. (Sun,) studied this question.