Evidence for Electron Precipitation Diffused by Rising-Tone Quasiperiodic Whistler Waves in Extremely Low L-Shells Observed by CSES

Based on the observations by the sun-synchronous circular orbit China Seismo-Electromagnetic Satellite(CSES), a typical case of the rising-tone quasiperiodic (QP) emissions with a large period of around 2 min was reported to appear on the dayside on 23 October 2021. The frequency of QP waves ranges from 2,000 similar to 3,000 Hz and the wave spectral structure consists of four elements with right-handed polarization. Three elements of them are located at extremely low L-shells from 2 similar to 3.5. The periodic precipitating fluxes of 100 similar to 400 keV electrons were found in the conjugate region also observed by CSES, which appeared in the same magnetic field lines with the elements of QP waves, respectively. By numerical simulations of quasi-linear diffusion theory, we confirm that QP emissions can effectively precipitate energetic electrons near the loss cone into the atmosphere in the inner radiation belt. To our best knowledge, this is the first evidence that the rising-tone QP whistler waves scatter electrons in the inner radiation belt. This new finding will help to deepen our understanding of the electron precipitation dynamics in radiation belt physics. The whistler-mode quasiperiodic (QP) emissions with a repetition period from several seconds to several minutes have been reported by a large amount of satellites and ground-based detector stations observations, and their generation mechanisms have been studied a lot. However, the reports about diffusion or acceleration effects on the relativistic electrons induced by QP waves are rare and only a little focused on the outer radiation belts. CSES satellite with the sun-synchronous polar orbits at 507 km altitude provides an advantage to study the wave-particle interaction in the extremely low L-shell regions including the inner radiation belts. In this work, we present the rising-tone QP whistler waves observed by CSES satellite in the inner radiation belt. Simultaneously, the periodic precipitating fluxes of 100-400 keV electrons were found in the same magnetic field lines with the elements of QP waves, respectively. To our knowledge, this provides the first evidence that QP emissions can effectively precipitate energetic electrons into the atmosphere in the inner radiation belt. This scenario is confirmed by our numerical simulations of quasi-linear diffusion theory. This new finding will help to deeply understand the electron precipitation dynamics in radiation belt physics. The rising-tone quasi-periodic (QP) whistler waves are observed by CSES satellite in the inner radiation belt100 similar to 400 keV electrons within 30 degrees equatorial pitch angles in the conjugate region was periodically precipitatedQP whistler waves can efficiently diffuse relativistic electrons near the bounce loss cone in extremely low L-shells (L = 2 similar to 3.5)