Parameterization of the Latitudinal Dependence of ULF Waves in the Magnetosphere via Long‐Term Statistical Observations

Abstract

Ultra‐low frequency (ULF) waves are crucial drivers of energetic electron radial diffusion in Earth's radiation belts. However, present radial diffusion coefficients are predominantly derived for equatorially mirroring electrons, relying on ULF wave power models from near‐equatorial spacecraft. Here, we present a comprehensive statistical analysis of 3D‐resolved ULF wave fluctuations in the outer radiation belt. Our study utilizes data from the Arase mission and multiple THEMIS spacecraft, providing extensive coverage in magnetic latitude (MLat) and ‐shell. This combined data set is systematically binned by , magnetic local time (MLT), MLat, and geomagnetic activity index , from which a second‐order polynomial fit in and MLat is constructed. We reveal that the distribution of ULF fluctuation power across magnetic latitude strongly varies with . These findings provide a basis for developing more accurate, observationally‐informed radial diffusion coefficients.