Plasmapause Surface Waves Triggered by Substorms

Abstract

AbstractIn this study, we present in‐situ measurement on board Van Allen Probes showing that surface wave can cause oscillations of the plasmapause and modulate hiss and electron cyclotron harmonic (ECH) waves. Plasmapause surface wave (PSW) in Ps6 band was observed during an intense substorm on 16 July 2017, accompanied with quasi‐periodic emissions of hiss (positively correlated with plasma density) and ECH waves (anticorrelated with density). Phase relation between magnetic field and velocity perturbations indicate that the PSW was an eigenmode between southern and northern ionosphere. Measurements from ground‐based magnetometers suggest that such PSW propagates sunward at the dusk flank and were excited around the expansion phase of an intense substorm. Additional cases of PSWs are also presented to demonstrate that such waves are commonly observed near plasmapause and are likely to be related to the substorm activity.