报告摘要：Chorus waves are intense electromagnetic coherent whistler mode waves typically observed outside the plasmapause. Their spectra are usually divided into two frequency bands and exhibit discrete elements, with rising-tone or falling-tone structures. Chorus waves are typically excited in the equatorial region though linear and nonlinear resonant interactions due to free energy from hot and anisotropic electrons (∼tens of keV) injected from the plasma sheet during geomagnetic storms and substorm activities.
In this report, I will present a systematic study of the characteristics of lower band rising tone chorus waves based on 7.5-year burst-mode observations from the Van Allen Probes. By developing an automated detection algorithm, individual chorus elements and their subpacket structures are extracted and statistically analyzed. Key properties, including element duration, frequency bandwidth, chirping rate, amplitude, and fine structure organization, are examined under different magnetic local time sectors and geomagnetic conditions.
The results reveal distinct spatial variations in chorus wave characteristics and strong correlations with the background plasma environment. Different types of subpackets tend to form via different generation mechanisms. These findings improve our understanding of chorus wave excitation and provide new insights into wave–particle interactions in the inner magnetosphere. |
