Radiation belt electron wisp inside South Atlantic Anomaly due to terrestrial VLF transmitter observed by MSS-1  

作　　者：Yixin SUN Ying LIU Qiugang ZONG Yixin HAO Hong ZOU Yuguang YE 

机构地区：[1]Institute of Space Physics and Applied Technology,Peking University,Beijing 100871,China [2]State Key Laboratory of Lunar and Planetary Science,Macao University of Science and Technology,Macao 999078,China [3]Max Planck Institute for Solar System Research,Goettingen 37077,Germany

出　　处：《Science China Earth Sciences》2025年第2期538-548,共11页中国科学(地球科学英文版)

基　　金：supported by the National Natural Science Foundation of China (Grant No. 42230202), the National Natural Science Foundation of China (Grant No. 42404171);the Major Project of Chinese National Programs for Fundamental Research and Development (Grant No. 2021YFA0718600);the China Postdoctoral Science Foundation (Grant No. 2023M730035)。

摘　　要：The South Atlantic Anomaly represents a region within near-Earth space characterized by a significantly weaker geomagnetic field and a higher flux of energetic particles compared to other areas. It is a space weather hazards to Low-EarthOrbit satellites. There has been evidence that the Very Low Frequency(VLF) waves from the powerful ground VLF radio transmitter in Australia, known as NWC, have the capacity to scatter energetic electrons' pitch angle in the inner radiation belt.The scattering directs electrons into the drift loss cone, forms a “wisp”, characterized by its peak intensity outside the South Atlantic Anomaly(SAA), and a “rift” exhibiting minimal intensity within SAA. Our findings mark the initial observation of a“wisp” precipitation, an unusual occurrence with peak intensity detected inside the SAA, observed via the Macao Science Satellite-1. Enabled by the Medium-energy Electron Spectrometer onboard Macao Science Satellite-1, we were able to comprehensively measure the full pitch angle distribution at Low-Earth-Orbit. This allowed us to attribute the “wisp” within the anomaly to a specific pitch angle range just outside the drift loss cone, a measurement unattainable by previous satellites. This“wisp” occurrence aligns with previous model predictions, despite being overlooked. Moreover, we distinguished between the trapped and precipitating electron populations. Directly derived from the ratio of these populations, our analysis revealed that approximately 2%-5% of trapped electrons will be lost in this specific wisp due to the influence of the ground VLF transmitter.Our results not only complement existing evidence of energetic electron pitch angle scattering facilitated by the ground VLF transmitter but also offer a quantitative estimation of its impact.

关 键 词：South Atlantic Anomaly Radiation belts Electrons precipitation VLF transmitter Wave-particle interaction 

分 类 号：P31[天文地球—固体地球物理学]