Statistical Relationship Between Exohiss Waves and Plasmaspheric Hiss
Jialiang Wang, L. Y. Li, Jiang Yu
Abstract
Abstract Based on the Van Allen Probe A observations from 2013 to 2015, we show the statistical relationship between exohiss waves and plasmaspheric hiss. Both hiss and exohiss waves have higher occurrence rates on the dayside (MLT = 8–20) and are positively correlated. The appearance of exohiss waves is nearly independent of the plasmapause density gradient at magnetic latitudes below 21°. Most exohiss waves (~ 68–88%) are propagating equatorward, and their amplitudes are generally smaller than those of hiss waves. This is consistent with the hiss leakage at high latitudes and associated energy dissipation. Less than 32% of exohiss waves are propagating poleward, probably due to multiple reflections of leaked hiss or excitation by equatorial instability. Although the inward reflection of chorus waves at high latitudes could produce equatorward propagating exohiss and hiss waves, this can explain only 10% of exohiss waves with larger amplitudes than hiss.