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Abstract We study the geomagnetic storm of 9 October 2012, where it had been generally accepted that the resulting prominent outer radiation belt electron acceleration throughout the storm is due to whistler‐mode chorus waves. This storm has been studied previously by two‐dimensional Fokker–Planck numerical simulations with data‐driven quasi‐linear (QL) diffusion rates. However, possible nonlinear (NL) resonant interaction effects on electron flux dynamics haven't been looked at yet. This study aims to fill this gap by demonstrating that theory‐informed rescaling of QL diffusion rates accounting for contributions of NL resonant interactions helps to reproduce better observed increase of electron fluxes by diffusion simulations. We use machine learning, uncertainty quantification (UQ), physics‐perturbed ensemble of VERB simulations and Van Allen Probes observations to identify optimal rescaling of quasi‐linear diffusion rates. 

We present a reconstruction of radiation belt electron fluxes using data assimilation with low-Earth-orbiting Polar Orbiting Environmental Satellites (POES) measurements mapped to near equatorial regions. Such mapping is a challenging task and the appropriate methodology should be selected. To map POES measurements, we explore two machine learning methods: multivariate linear regression (MLR) and neural network (NN). The reconstructed flux is included in data assimilation with the Versatile Electron Radiation Belts (VERB) model and compared with Van Allen Probes and GOES observations. We demonstrate that data assimilation using MLR-based mapping provides a reasonably good agreement with observations. Furthermore, the data assimilation with the flux reconstructed by NN provides better performance in comparison to the data assimilation using flux reconstructed by MLR. However, the improvement by adding data assimilation is limited when compared to the purely NN model which by itself already has a high performance of predicting electron fluxes at high altitudes. In the case an optimized machine learning model is not possible, our results suggest that data assimilation can be beneficial for reconstructing outer belt electrons by correcting errors of a machine learning based LEO-to-MEO mapping and by providing physics-based extrapolation to the parameter space portion not included in the LEO-to-MEO mapping, such as at the GEO orbit in this study.