Journal Article

On the Relationship Between the Banded Hiss Distribution and Plasmapause Location: A Survey of Van Allen Probes Observations

Xiang, Zheng, Dong, Junhu, Ni, Binbin

2024

Overview

The plasmapause is the outer boundary of the plasmasphere and plays a crucial role in the propagation of plasma waves. We statistically investigate the relationship between the distribution of banded hiss and plasmapause locations. Wave power distributions of banded hiss are analyzed in terms of two ways: (a) the distance away from the plasmapause (ΔL) and (b) the equatorial distance away from the Earth. Statistical results show both bands of banded hiss have larger wave powers and occurrence rates near the plasmapause. The frequencies of two banded hiss waves both decrease discernably with increasing L‐shell at most magnetic local time sectors and geomagnetic activities, but remain nearly constant with increasing ΔL. The highly consistent distribution suggests both bands may be generated in the plume region. The correlation between banded hiss waves and plasmapause locations sheds new light on the generation mechanisms of banded hiss waves. Plain Language Summary Plasmaspheric hiss is a whistler‐mode emission with a broad frequency range from ∼20 Hz to several kHz. The wave is generally observed inside the dayside plasmasphere and plumes. Hiss wave powers are modulated by the combining effect of many parameters such as L (the distance of observation away from the Earth), MLT (magnetic local time), geomagnetic activities, and plasmapause locations. Owing to the difference in electron density inside and outside the plasmapause, the chorus may be damped when propagating into the plasmasphere, and hiss waves in the plasmasphere can be reflected when they propagate near the plasmapause. Recently, A new banded structure of hiss has been reported with a lower band below ∼100 Hz and an upper band above ∼200 Hz. Using ∼7 years measurements of Van Allen Probes, we statistically investigate the distribution of banded hiss wave power with respect to the plasmapause location. The L, MLT, and geomagnetic activities are also considered. Our results suggest that banded hiss wave power shows a strong correlation with the location of plasmapause. Banded hiss waves closer to the plasmapause show larger powers. Plasmapause‐sorted banded hiss wave power can be used to better understand the generation and propagation mechanisms of banded hiss. Key Points The intensity distributions of banded hiss with plasmapause locations at different MLTs under various geomagnetic levels are investigated In statistics, the frequencies of two banded hiss waves decrease discernably with increasing L, but remain nearly constant with ΔL Banded hiss waves with larger amplitudes usually occur close to the plasmapause, implying both bands may be generated in the plume

• Publisher: John Wiley & Sons, Inc
• Subject: banded hiss / Banded structure / Distance / Earth / Earth's radiation belt / Electric power distribution / Electron density / Equatorial regions / Frequency ranges / Geomagnetic activity / Geomagnetism / Hiss / Plasma waves / Plasmapause / plasmapause location / Plasmasphere / plasmaspheric hiss / Plumes / Probes / Wave power / Wave propagation