On the Close Correspondence between Storm-time ULF Wave Power and the POES VLF Chorus Wave Amplitude Proxy
Abstract
Ground-based Pc5 ULF wave power in multiple ground-based meridians is compared to the VLF wave amplitude proxy, derived from POES precipitation, for the 33 storms studied by Li et al. [2015]. The results reveal common L-shell and time profiles for the ULF waves and VLF proxy for every single storm, especially at L≤ 6, and identical discrimination between efficient and inefficient radiation belt electron acceleration. The observations imply either ULF waves play a role in driving precipitation which is falsely interpreted as VLF wave power in the proxy, ULF waves drive VLF waves (the reverse being energetically unfeasible), or both have a common driver with nearly identical L-shell and time-dependence. Global ground-based ULF wave power coherence implies a small number of meridians can be used to estimate storm-time radial diffusion coefficients. However, the strong correspondence between ULF wave power and VLF wave proxy complicates causative assessments of electron acceleration.