[P-EM07] Dynamics in magnetosphere and ionosphere

[PEM07-P04] Interactions of energetic electrons with low-m number ULF waves in the inner magnetosphere during a storm recovery phase

*寺本 万里子¹、藤本 晶子²、坂口 歌織³、能勢 正仁⁴、三好 由純⁵、Kletzing Craig⁶、Singer Howard⁷、松岡 彩子¹ (1.宇宙航空研究開発機構　宇宙科学研究所、2.九州大学、3.情報通信研究機構、4.京都大学大学院　理学研究科、5.名古屋大学　宇宙地球環境研究所、6.アイオワ大学、7.NOAA Space Weather Prediction Center)

A number of previous studies have suggested that ULF waves, which occur during a recovery phase of a geomagnetic storm, are associated with the enhancement of electron flux in the outer radiation belt. ULF waves accelerate electrons whose drift velocities match the azimuthal phase velocities of ULF waves via drift resonance. Elkington et al., (1999 and 2003) proposed a simple model for the drift resonance effect on energetic electrons due to ULF toroidal and poloidal modes with large azimuthal wavelengths (low m numbers). Although some observational studies (Tan et al.,2004 and 2011) reported effects of low-m number ULF waves on electron acceleration, the interaction between low-m number ULF waves and energetic electrons is still incompletely understood.
In this study, we investigate interaction between low-m number ULF and energetic electron observed in the inner magnetosphere, using data from the multiple satellites, GOES 13, 15 and Van Allen probes. A Pc5 pulsation occurring at 6:00-8:00 UT on 13 September 2014 during a storm recovery phase are focused on. These Pc5 pulsations are dominated by the toroidal component with the frequency of a 3 mHz and a large amplitude of 30 nT when Van Allen Probes were located on the morning side (MLT~5) at L~6. Estimating m number from the phase difference of Pc5 pulsations and azimuthal separation between Van Allen Probes A and B, the Pc5 has an m number of 3 with westward propagation. Perturbations corresponding to the Pc5 pulsation are observed in the electron flux data. In this presentation, we discuss weather Pc5 pulsations accelerate the energetic electron via the drift resonant interaction.