On the Close Correspondence between Storm-time ULF Wave Power and the POES VLF Chorus Wave Amplitude Proxy

TL;DR

This study finds a strong correlation between ground-based ULF wave power and POES VLF chorus wave amplitude proxy during storms, suggesting a shared driver or interaction affecting radiation belt dynamics.

Contribution

It demonstrates a consistent L-shell and temporal profile correspondence between ULF waves and VLF proxies across multiple storms, highlighting potential implications for electron acceleration analysis.

Findings

ULF wave power and VLF proxy share similar storm-time profiles

Strong correlation complicates causative interpretation of electron acceleration

Few meridians suffice to estimate radial diffusion coefficients

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 $L\leq 6$, 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.