Latitudinal Distributions and Harmonic Characteristics of Pc3-5 Waves in Electric Field Measured by Arase Satellite

Abstract

Ultra-Low Frequency (ULF) waves can significantly influence the acceleration and rapid loss of radiation belt electrons. Based on about 7 years of Arase measurements, we investigate the latitudinal distribution of the wave power of poloidal and toroidal modes of the electric field in the Pc3-5 band. For Pc5 waves, the wave power of both poloidal and toroidal modes increases with latitude, consistent with the latitudinal enhancement trend observed in Cluster measurements by Yan et al. (2025, https://doi.org/10.1029/2024gl112358). For Pc3-4 wave, the latitudinal distribution of the electric field ULF waves power exhibits patterns consistent with the second and higher harmonic modes, as predicted by the theoretical model described by Cummings et al. (1969, https://doi.org/10.1029/ja074i003p00778). Furthermore, the effect of Kp on ULF wave power increases with latitude in the Pc3-5 band. The wave power of electric field ULF waves in the Pc3-5 band is approximately 3–4 times higher for Kp $>$ 2 compared to Kp $\le$ 2. The results of the latitudinal distribution characteristic of ULF waves in the Pc3-5 bands can contribute to further investigation on the estimation of 3-D radial diffusion coefficients.