基于JUNO卫星WAVES仪器波动数据的木星磁层哨声波分析研究

等离子体波的空间分布在木星磁层高能电子动力学过程中起着重要的作用.现有大多数对木星磁层哨声波的观测仅限于|λ|≤15°的磁纬范围内,但是最新的JUNO卫星WAVES仪器提供的波动数据使得更高纬度、更广区域范围内的等离子体波动分布研究成为可能.本文通过对JUNO卫星WAVES仪器数据进行分析处理,详细研究了木星磁层哨声波的空间分布特性.观测表明,存在位于高LJ、高磁纬的木星磁层哨声波,它们广泛分布于距木星中心距离35～75个木星半径、磁纬为|λ|≤30°的空间区域.分析研究发现,WAVES仪器观测的木星磁层哨声波幅度一般为几个pT,远小于地球磁层哨声波的强度.木星磁层哨声波幅会随着LJ的增大缓慢增加,也会随着磁纬的减小趋向平缓变化.基于以上观测事实,本文利用指数幂函数分别拟合得到木星磁层哨声波幅随LJ和磁纬变化的经验模型.该模型将有助于精确理解哨声波对木星磁层高能电子动力学过程的重要影响.

Analysis of whistler waves in the Jovian magnetosphere based on data from JUNO WAVES Instrument

Spatial distributions of plasma waves play an essential role in the dynamics of Jovian magnetospheric electrons. Despite that most previous observations of whistler waves in the Jovian magnetosphere are limited to|λ|≤ 15° of the magnetic equator, the data availability from JUNO WAVES instrument provides good opportunity to capture plasma waves over a broader range of latitude and distance. By using the datasets obtained from JUNO WAVES instrument, the spatial distribution features of whistler waves in the Jovian magnetosphere are studied in detail. The observations indicate that whistler waves occur widely in the region between 35~75 R_J (the Jupiter's radius) within 30° of the magnetic equator. The average amplitude of whistler waves in the Jovian magnetosphere is generally at the level of several pT, weaker than that in the terrestrial magnetosphere. Whistler wave intensities at Jupiter are also found to exhibit a tendency of slow increase with increasing L_J and gradual stability with decreasing magnetic latitude. Based on these observational results, we implement fits of exponential power-law function to develop an empirical model of the variation of Jovian whistler wave amplitude with L_J and magnetic latitude, which can be used readily to contribute to improved understanding of the importance of whistler waves to the dynamical variations of high energy electrons in the Jovian magnetosphere.