Forecasting and remote sensing outer belt relativistic electrons from low Earth orbit

This study demonstrates the feasibility and reliability of using observations from low Earth orbit (LEO) to forecast and nowcast relativistic electrons in the outer radiation belt. We first report a high cross‐energy, cross‐pitch‐angle coherence discovered between the trapped MeV electrons and precipitating approximately hundreds (~100s) of keV electrons—observed by satellites with very different altitudes—with correlation coefficients as high as ≳ 0.85. Based upon the coherence, we then tested the feasibility of applying linear prediction filters to LEO data to predict the arrival of new MeV electrons during geomagnetic storms, as well as their evolving distributions afterward. Reliability of these predictive filters is quantified by the performance efficiency with values as high as 0.74 when driven merely by LEO observations (or up to 0.94 with the inclusion of in situ MeV electron measurements). Finally, a hypothesis based upon the wave‐particle resonance theory is proposed to explain the coherence, and a first‐principle electron tracing model yields supporting evidence. Key Points Event‐specific behavior of MeV electrons can be predicted from LEO observations with high fidelity Dominance of in situ wave‐particle interactions explains cross‐energy, cross‐pitch‐angle coherence A new reliable and powerful approach to forecasting and nowcasting the outer belt electrons