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SHELLS-hires (1)

Specifying High-altitude Electrons using Low-altitude LEO Satellites

Model Description

The SHELLS electron radiation belt model was developed to easily and accurately describe the near-Earth electron flux environment both in real time and retrospectively in order to monitor and analyze space weather impacts to satellites on-orbit. The high energy electrons modeled by SHELLS can penetrate through satellite shielding and build up charge in dielectric materials and on spot shields sometimes resulting in a sudden electrical discharge that triggers anomalous satellite behavior. The model specifies electron flux at high altitude locations (L=3-6.3 and a range of near equatorial and off equatorial magnetic field values) by mapping electron fluxes measured at low altitudes (~850 km) by the POES/MetOp satellite constellation using a neural network derived algorithm.   

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Model Inputs Description

SHELLS is driven by near real time measurements of low altitude electron fluxes and the Kp-index. More specifically, it uses the log10 of the integral electron fluxes measured by the MEPED instruments along each complete pass of a POES/MetOp satellite through the radiation belts (L=3-8). The data from each pass are binned into .25 L shell bins that are then mapped to a consistent longitude and hemisphere using statistical asynchronous regression to remove orbital variations (see Green et al. [2021] for details on the input data processing). Additionally, it uses the Kp index and the maximum Kp index in the last 3 days (here Kp is the standard index multiplies by 10)

Model Outputs Description

The general output of the SHELLS model is electron fluxes (#/cm2-s-str-keV) from L=3-6.3 and energies from 200-3000 keV with local pitch angles from 0-90 degrees. 

The SHELLS model provides 2 different real time run products. One is a dataset of electron flux along the trajectory of a GPS satellite. The output for this GPS product is a text file and L binned plots of the electron fluxes for the last 25 days. The output files contain time at a 5-minute cadence, the L shell based on the OP Quiet field (L), the flux (columns called E flux xxx keV) of electrons with local 90-degree pitch angle and energies 200,500,800,1000,2000 keV, the upper and lower quartiles of the flux (columns labeled upper q and lower q), and the local B field from the OP Quiet field model. 

The other dataset contains near equatorial electron flux at a fixed set of L-shells (3,3.5,4,4.5,5,5.5,6) and energies (200-3000 at a 200keV step). The daily JSON files update every hour and contain data at a 1-hour times cadence. The values included in the JSON file are time, Eflux[time,Ls,energy], L[time,L], Bmirror[time,L], upper q[time,L,energy], lower q[time,L,energy], Kp[time], and Kp max[time]. Here upper q is the upper quartile of the electron flux and lower q is the lower quartile. Kp is the Kp index and Kp max is the maximum in the prior 3 days.

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Curator: Chiu Wiegand | NASA Official: Dr. Masha Kuznetsova | Privacy and Security Notices | Accessibility | CCMC Data Collection Consent Agreement