Global time‐dependent chorus maps from low‐Earth‐orbit electron precipitation and Van Allen Probes data

Abstract Substorm injected electrons (several–100 s keV) produce whistler‐mode chorus waves that are thought to have a major impact on the radiation belts by causing both energization and loss of relativistic electrons in the outer belt. High‐altitude measurements, such as those from the Van Allen Probes, provide detailed wave measurements at a few points in the magnetosphere. But physics‐based models of radiation‐belt dynamics require knowledge of the global distribution of chorus waves. We demonstrate that time‐dependent, global distributions of near‐equatorial chorus wave intensities can be inferred from low‐Earth‐orbit (LEO) measurements of precipitating low‐energy electrons. We compare in situ observations of near‐equatorial chorus waves with LEO observations of precipitating electrons and derive a heuristic formula that relates, quantitatively, electron precipitation fluxes to chorus wave intensities. Finally, we demonstrate how that formula can be applied to LEO precipitation measurements and in situ Van Allen Probes wave measurements to provide global, data‐driven inputs for radiation belt models.