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Abstract Maintaining accurate real‐time hindcast and forecast specification of the radiation environment is essential for operators to monitor and mitigate the effects of hazardous radiation on satellite components. The Radiation Belt Forecasting Model and Framework (RBFMF) provides real‐time forecasts and hindcasts of the electron radiation belt environment, which are used as inputs for the Satellite Charging Assessment Tool. We evaluated the long‐term statistical error and bias of the RBFMF by comparing the 10‐hr hindcast of electron phase space densities (PSD) to a multi‐mission data set of PSD observations. We found that, between the years 2016–2018, the RBFMF reproduced the radiation belt environment to within a factor of 1.5. While the error and bias of assimilated observations were found to influence the error and bias of the hindcast, data assimilation resulted in more accurate specification of the radiation belt state than real‐time Van Allen Probe observations alone. Furthermore, when real‐time Van Allen Probe observations were no longer available, the hindcast errors increased by an order of magnitude. This highlights two needs; (a) the development of physics‐based modeling incorporated into this framework, and (b) the need for real‐time observations which span the entire outer radiation belt. 

Abstract The proton radiation belt contains high fluxes of adiabatically trapped protons varying in energy from ∼one to hundreds of megaelectron volts (MeV). At large radial distances, magnetospheric field lines become stretched on the nightside of Earth and exhibit a small radius of curvatureR_Cnear the equator. This leads protons to undergo field line curvature (FLC) scattering, whereby changes to the first adiabatic invariant accumulate as field strength becomes nonuniform across a gyroorbit. The outer boundary of the proton belt at a given energy corresponds to the range of magneticLshell over which this transition to nonadiabatic motion takes place, and is sensitive to the occurrence of geomagnetic storms. In this work, we first find expressions for nightside equatorialR_Cand field strengthB_eas functions of Dst andL* to fit the TS04 field model. We then apply the Tu et al. (2014,https://doi.org/10.1002/2014ja019864) condition for nonadiabatic onset to solve the outer boundaryL*, and refine our expression forR_Cto achieve agreement with Van Allen Probes observations of 1–50 MeV proton flux over the 2014–2018 era. Finally, we implement this nonadiabatic onset condition into the British Antarctic Survey proton belt model (BAS‐PRO) to solve the temporal evolution of proton fluxes atL ≤ 4. Compared with observations, BAS‐PRO reproduces storm losses due to FLC scattering, but there is a discrepancy in mid‐2017 that suggests a ∼5 MeV proton source not accounted for. Our work sheds light on outer zone proton belt variability at 1–10 MeV and demonstrates a useful tool for real‐time forecasting. 

Abstract 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 atL = 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 amplitudeB_w, chorus wave peak frequencyf_m, background magnetic fieldB₀, and electron densityN_e, we ran 11⁴simulations 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 inB_w,N_e, andf_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 ∼−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. 

Archived data for the manuscript “Differentiating Between Simultaneous Loss Drivers in Earth’s Outer Radiation Belt: Multi-Dimensional Phase Space Density Analysis”  Staples et al., submitted to Geophysical Research Letters 2022.</p> These files contain multi-mission phase space density measurements including, Van Allen Probes, GOES 13, 14, 15, GPS, MMS, and THEMIS, computed in adiabatic coordinates. All data is from September 2017. For detailed description of the method used in the computation of this data, see section 2.1 of the submitted manuscript. The THEMIS, Van Allen Probe, MMS, and GOES data used in computations is publicly available via http://cdaweb.gsfc.nasa.gov  The GPS data is available via https://www.ngdc.noaa.gov/stp/space-weather/satellite-data/satellite-systems/gps/</p> FILES:</p> 'psd_intp_T89_20170901-20170930_allsc.cdf'</p> 'psd_intp_T89_20170901-20170930_rbsp-b.cdf'</p> DATA OWNER: Adam Kellerman DATA PREPERATION: Frances Staples</p> CONTACT: Adam Kellerman: akellerman@epss.ucla.edu Frances Staples: frances.staples@ucl.ac.uk</p> FS was supported by NASA grants 80NSSC20K1402 and NSF grant 2149782. ACK acknowledges support from NASA grants 80NSSC20K1402 and 80NSSC20K1281, and NSF grant 2149782.