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- Title
Frequency‐Drifting Plasmaspheric Hiss: A Statistical Study From the Van Allen Probes Data.
- Authors
Yi, Siyang; Liu, Nigang; Xie, Yi; He, Zhaoguo; Yu, Jiang; Cui, Jun
- Abstract
Plasmaspheric hiss, a whistler‐mode emission confined in the high‐density plasmasphere, is of great interest to the space community attributed to its important role in inner magnetospheric dynamics. Their frequency‐time structures provide crucial evidence for understanding the wave origin. In this work, based on ∼7‐year Van Allen Probes data, we statistically studied the frequency‐drifting plasmaspheric hiss characterized by an increasing lower cutoff frequency over a timescale exceeding 1 hr. Frequency‐drifting hiss waves predominantly occur at 3 < L < 6 from predawn to noon during geomagnetic active times. Observations and theoretical analyses suggest the frequency‐drifting hiss could result from the local excitation inside the plasmasphere by energy‐dispersive injected electrons. This unique feature of plasmaspheric hiss waves serves, to a certain extent, as an "identifier" for discerning the wave origins and as a "marker" facilitating the link between hiss waves across a broad spatial range. Plain Language Summary: Inside the plasmasphere, a cold and dense plasma region surrounding the Earth, plasmaspheric hiss is a frequently observed electromagnetic wave. Through wave‐particle interactions, plasmaspheric hiss plays a critical role in controlling the geospace environment. Since their discovery in the 1960s, there have been intense debates regarding the generation mechanisms of plasmaspheric hiss. Fortunately, the frequency‐time structure of plasmaspheric hiss provides valuable evidence to understand the wave origin. In this work, on the basis of long‐term observations from Van Allen Probes, we statistically investigate the frequency‐drifting plasmaspheric hiss characterized by an increasing lower cutoff frequency over a timescale exceeding 1 hr. Our analyses indicate this frequency‐drifting feature could be used to some extent to identify the origin of hiss waves. Key Points: We investigate the frequency‐drifting plasmaspheric hiss characterized by an increasing lower cutoff over a timescale exceeding 1 hrFrequency‐drifting hiss waves predominantly occur at 3 < L < 6 from predawn to noon during geomagnetic active timesThe frequency‐drifting feature could result from the local excitation by energy‐dependent dispersive injection of hot electrons
- Subjects
HOT carriers; DENSE plasmas; LOW temperature plasmas; ELECTROMAGNETIC waves
- Publication
Geophysical Research Letters, 2024, Vol 51, Issue 8, p1
- ISSN
0094-8276
- Publication type
Article
- DOI
10.1029/2024GL108448