A statistical analysis of the global distribution of inner magnetospheric lower-band chorus waves based on Van Allen Probes EMFISIS observations

作者：Gu Xu-Dong; Yin Qian; Ni Bin-Bin^*; Xiang Zheng; Cao Xing; Zou Zheng-Yang; Zhou Chen; Fu Song; Shi Run; Zhao Zheng-Yu; Tan Jia-Qiang; Wang Hao; Zheng Cheng-Yao; He Feng-Ming

来源：Acta Geophysica Sinica, 2017, 60(4): 1249-1258.

DOI：10.6038/cjg20170401

• Lower-band chorus
• Inner magnetosphere
• Statistical analysis
• Average wave amplitude
• Occurrence rate

Based on the nearly three-year wave data from the EMFISIS instrument onboard the Van Allen Probes, a statistical analysis of the global distribution of inner magnetospheric lower-band chorus is performed in detail with respect to the level of geomagnetic activity. The emphasis is placed on the quantitative variations of average lower-band chorus wave amplitude with L-shell, magnetic local time (MLT) and geomagnetic latitude and the occurrence pattern of lower band chorus waves at different amplitude levels. The results indicate that there exists a strong positive correlation between the average wave amplitude and the geomagnetic activity level. The lower-band chorus intensifies with increasing geomagnetic activity. The occurrence rates of lower band chorus also tend to increase when the geomagnetic condition intensifies. Lower-band chorus mainly occur in the MLT sector from midnightside to afternoon, and is generally weak at other MLTs. Near the geomagnetic equator, lower-band chorus is mainly observed during the interval from nightside to dawn and has a MLT extension to dayside at higher magnetic latitudes. Lower band chorus is mainly confined within 15 of the magnetic latitude around the midnightside (21-03 MLT), while it can propagate to higher latitudes on the dawnside (03-09 MLT). The global profile of lower-band chorus also manifests a strong L-shell dependence, showing the highest probability of the wave occurrence at L=similar to 4. 5 generally and a much broader coverage during geomagnetically active periods. These results concerning the global distribution and occurrence pattern of lower-band chorus are important to deepen the current understanding of the wave driven scattering effect on radiation belt electrons via wave-particle interactions and of the quantitative contributions to the dynamic behaviors of radiation belt electrons.

• 出版日期2017-4
• 单位武汉大学