TY  - JOUR
A1  - Cervantes, Sebastian
A1  - Shprits, Yuri Y.
A1  - Aseev, Nikita
A1  - Drozdov, Alexander
A1  - Castillo Tibocha, Angelica Maria
A1  - Stolle, Claudia
T1  - Identifying radiation belt electron source and loss processes by assimilating spacecraft data in a three-dimensional diffusion model
JF  - Journal of geophysical research : Space physics
N2  - Data assimilation aims to blend incomplete and inaccurate data with physics-based dynamical models. In the Earth's radiation belts, it is used to reconstruct electron phase space density, and it has become an increasingly important tool in validating our current understanding of radiation belt dynamics, identifying new physical processes, and predicting the near-Earth hazardous radiation environment. In this study, we perform reanalysis of the sparse measurements from four spacecraft using the three-dimensional Versatile Electron Radiation Belt diffusion model and a split-operator Kalman filter over a 6-month period from 1 October 2012 to 1 April 2013. In comparison to previous works, our 3-D model accounts for more physical processes, namely, mixed pitch angle-energy diffusion, scattering by Electromagnetic Ion Cyclotron waves, and magnetopause shadowing. We describe how data assimilation, by means of the innovation vector, can be used to account for missing physics in the model. We use this method to identify the radial distances from the Earth and the geomagnetic conditions where our model is inconsistent with the measured phase space density for different values of the invariants mu and K. As a result, the Kalman filter adjusts the predictions in order to match the observations, and we interpret this as evidence of where and when additional source or loss processes are active. The current work demonstrates that 3-D data assimilation provides a comprehensive picture of the radiation belt electrons and is a crucial step toward performing reanalysis using measurements from ongoing and future missions.
KW  - acceleration
KW  - code
KW  - density
KW  - emic waves
KW  - energetic particle
KW  - mechanisms
KW  - reanalysis
KW  - ultrarelativistic electrons
KW  - weather
Y1  - 2019
U6  - https://doi.org/10.1029/2019JA027514
SN  - 2169-9380
SN  - 2169-9402
VL  - 125
IS  - 1
PB  - American Geophysical Union
CY  - Washington
ER  -