Derivation of D-region Electron-Density Profile Using New Multi-Frequency Riometer Instruments

Abstract:

In the auroral region, the primary source of D-region ionization is the precipitation of magnetospheric high energy electrons. Continuous measurements of D-region electron density profiles would therefore provide critical information for studying the effects of the magnetospheric driving of ionospheric properties, and also allow for inversion of ionospheric properties into magnetospheric particle source characteristics (with the aid of appropriate models). One of the most cost-effective remote sensing instruments for monitoring ionospheric electron density is the riometer (relative ionospheric opacity meter). Historically, large, spatially distributed arrays of riometers have been single frequency systems (e.g. 30MHz). While these single frequency systems are extremely useful for large scale studies of the spatial and temporal characteristics of precipitation and remote sensing large scale magnetospheric phenomena (such as the injection), they lack the depth of information necessary to remote sense D-region properties with a high degree of certainty. In this study, we present new measurements from a recently funded development program to upgrade much of the Canadian riometer network to adaptable multi-frequency systems. Specially, we present the absorption spectrum measured by a prototype multi-frequency riometer deployed in Gillam, MB during the timeframe of November to December 2019. We use the multi-frequency information provided by the riometer to derive corresponding D-region electron density profiles. We also comment on the future utility of these measurements as a continuous measurement of ionospheric D-region electron density for both magnetospheric science and space weather applications.