Distribution characteristics of trapped Terrestrial Myriametric Radiation in the magnetosphere

The trapped Terrestrial Myriametric Radiation (TMR) is a widely observed emission in the magnetosphere with wavelengths of myriameters (frequencies \leq 30 kHz), and consists of the fast and slow Z-modes. Based on measurements from the Arase satellite during the period of 23 March 2017 to 31 October 2022, we investigate the distribution characteristics of trapped TMR in the magnetosphere. We analyze trapped TMR events with the electric field power spectral density \geq 10^-8 \rmmV^2 \rmm^-2\rmHz^-1 and in the frequency range of 7−30 kHz. Statistical results show that the trapped TMR occurs more frequently on the nightside, and the corresponding occurrence rate increases with the increasing magnetic latitude in the region of 0\text° − 45\text° . The occurrence rate of fast (slow) Z-mode increases (decreases) as the L -shell increases. In addition, the fast (slow) Z-mode occurs more frequently in the southern (northern) hemisphere. This study enriches our understanding of various electromagnetic waves in the magnetosphere.