Lightning Generated Whistlers: Variability of Event‐Based Wave Distributions

Abstract Lightning‐generated whistlers (LGWs) are an important wave mode in the inner magnetosphere, where they play a strong role in the radiation belt slot region formation through scattering of radiation belt electrons into the loss cone. Recent LGW studies have calculated time‐averaged wave parameters which are then used to calculate quasi‐linear diffusion coefficients. This is not always appropriate as the diffusion coefficient of the time‐averaged wave parameters is not the same as the averaged local diffusion coefficient. In this study, the event‐to‐event variability of LGW wave parameters is investigated using high resolution burst data from both Electric Fields and Waves and Electric and Magnetic Field Instrument Suite and Integrated Science onboard the Van Allen Probes over the entirety of the mission. For each burst interval containing LGWs, the burst‐averaged magnetic power spectral density is fit with a quadratic polynomial (justified by the theoretical source spectra), and the wave normal angle () power distribution is fit with a Gaussian. There is significant variability of the LGW frequency spectra but the distribution that describes that variability is relatively constant with respect to location in the inner magnetosphere. No dependence on the location of the plasmapause is found. The typical event‐specific LGW wave amplitude peaks around 35 pT, an order‐of‐magnitude higher than previously reported time‐averaged values. It is also found that the LGW power distribution is Gaussian in , not , as is typically assumed in diffusion coefficient calculations. This study provides the community with a comprehensive, multi‐instrument data set of event‐specific LGW wave parameters.