Statistical Analysis of Hiss Waves in Plasmaspheric Plumes Using Van Allen Probe Observations. Issue 3 (28th March 2019)

• Record Type: Journal Article
• Authors: Kim, Kyung‐Chan; Shprits, Yuri
• Is Part Of: Journal of geophysical research. Volume 124:Issue 3(2019)
• Page Start: 1904
• Page End: 1915
• Publication Date: 2019-03-28
• Subjects: plasmaspheric hiss -- plasmaspheric plume -- Van Allen Probes; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2018JA026458
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: Plasmaspheric hiss waves commonly observed in high‐density regions in the Earth's magnetosphere are known to be one of the main contributors to the loss of radiation belt electrons. There has been a lot of effort to investigate the distributions of hiss waves in the plasmasphere, while relatively little attention has been given to those in the plasmaspheric plume. In this study, we present for the first time a statistical analysis of the occurrence and the spatial distribution of wave amplitudes and wave normal angles for hiss waves in plumes using Van Allen Probes observations during the period of October 2012 to December 2016. Statistical results show that a wide range of hiss wave amplitudes in plumes from a few picotesla to >100 pT is observed, but a modest (<20 pT) wave amplitude is more commonly observed regardless of geomagnetic activity in both the midnight‐to‐dawn and dusk sector. By contrast, stronger amplitude hiss occurs preferentially during geomagnetically active times in the dusk sector. The wave normal angles are distributed over a broad range from 0° to 90° with a bimodal distribution: a quasi‐field‐aligned population (<20°) with an occurrence rate of <60% and an oblique one (>50°) with a relative low occurrence rate of ≲20%. Therefore, from a statistical point of view, we confirm that the hiss intensity (a few tens of picotesla) and field‐aligned hiss wave adopted in previous simulation studies are a reasonable assumption but stress that the activity dependence of the wave amplitude should be considered. Key Points: Hiss waves in the plasmaspheric plumes are statistically investigated A clear magnetic activity dependence of hiss amplitude is observed A much higher occurrence of field‐aligned hiss waves than oblique hiss waves is observed