Global Observations of Electron Injections Using Data From Ground-Based Instruments.

Relative Ionospheric Opacity Meters (riometers) are ground-based passive radio receivers that monitor cosmic radio noise (CRN). Increased electron densities, primarily in the ionospheric D region, lead to absorption of this CRN. In as much as this increased electron density is the result of precipitation of high-energy electrons from the magnetosphere, absorption of CRN is a proxy for that precipitation. Particularly for riometers that are magnetically conjugate to the inner magnetosphere, it has been shown that CRN absorption is a proxy for integrated fluxes of electrons near the equatorial plane of the magnetosphere [Baker et al., 1981]. Spanswick et al. [2007] showed that it is possible to identify the signature of dispersionless electron injections in riometer data. In this work, we demonstrate that we can track the global evolution of an electron injection, subject to a few caveats (for example, the electrons must be in strong pitch angle diffusion near the conjugate magnetospheric equator). We show examples of injections observed in Canada and subsequently in Finland, use the time delay to infer a peak energy for the injected electrons, and compare that peak energy to that observed by plasma detectors on geosynchronous satellites.