Prompt Modulation of Plasmaspheric Hiss by Solar Wind Dynamic Pressure Pulses

Abstract

Plasmaspheric hiss plays a crucial role in radiation belt electron dynamics. Using Van Allen Probes data from 2012 to 2019, we systematically examine the response of hiss waves to solar wind dynamic pressure pulses. The results reveal a bidirectional modulation of hiss amplitudes: positive pressure pulses tend to enhance wave intensities, while negative pulses generally suppress them. Following pulse impacts, hiss typically weakens on the dayside but enhances on the nightside, indicating a distinct dayside–nightside asymmetry. Besides, wave normal angles significantly increase during suppression events and slightly decrease during enhancements, suggesting pulse–driven propagation shifts. These coordinated variations indicate that plasmaspheric hiss is dynamically responsive to external solar wind forcing, with implications for modeling wave distributions and electron scattering processes in the inner magnetosphere.