Ensemble Modeling of Radiation Belt Electron Acceleration by Chorus Waves: Dependence on Key Input Parameters

We perform ensemble simulations of radiation belt electron acceleration using the quasi-linear approach during the storm on 9 October 2012, where chorus waves dominated electron acceleration at L = 5.2. Based on a superposed epoch analysis of 11 similar storms when both multi-MeV electron flux enhancements and chorus wave activities were observed by Van Allen Probes, we use percentiles to sample the normalized input distributions for the four key inputs to estimate their relative perturbations. Using 11 points in each input parameter including chorus wave amplitude B-w, chorus wave peak frequency f(m), background magnetic field B-0, and electron density N-e, we ran 11(4) simulations to quantify the impact of uncertainties in the input parameters on the resulting simulated electron acceleration by chorus. By comparing the simulations to observations, our ensemble simulations reveal that inaccuracies in all four input parameters significantly affect the simulated electron acceleration, with the largest simulation errors attributed to the uncertainties in B-w, N-e, and f(m). The simulation can deviate from the observations by four orders of magnitude, while members with largest probability density (smallest perturbations in the input) provide reasonable estimations of output fluxes with log accuracy errors concentrated between similar to-2.0 and 0.5. Quantifying the uncertainties in our study is a prerequisite for the validation of our radiation belt electron model and improvements of accurate electron flux predictions. The ensemble modeling technique has only been embraced by the space weather community for about 20 years and is a powerful numerical method that can help us understand how the uncertainty propagates in the model, as well as the confidence and range of simulated results. Quantifying the error distribution and model performance is important to improve space weather predictions. We perform an ensemble of simulations of radiation belt electron acceleration using the quasi-linear approach during the storm on 9 October 2012, where chorus waves dominated electron acceleration at L = 5.2. By conducting a superposed epoch analysis of 11 similar storms when both multi-MeV electron flux enhancements and chorus wave activities were observed, we improve the input data sampling in terms of both spatiotemporal coverage and extreme case coverage. The comparison between the ensemble simulations and observations allows us to quantify how the uncertainties in the simulated output fluxes are apportioned to inaccuracy in the input parameters. We also estimate the confidence of the simulation performance by calculating the probability density of the simulation error. Our sensitive analysis provides fundamental information for radiation belt model calibration and future accurate radiation belt electron predictions.