Electron density and electric field over Resolute Bay and F region ionospheric echo detection with the Rankin Inlet and Inuvik SuperDARN radars

Joint observations of the Rankin Inlet and Inuvik Super Dual Auroral Radar Network HF radars and Resolute Bay (RB) Canadian Advanced Digital Ionosonde are used to assess the electron density at the F region peak and the electric field magnitude as factors affecting echo detection over RB. We demonstrate that the radars show similar diurnal and seasonal variations in ionospheric echo occurrence. During nighttime and at radar frequencies of ∼12 MHz, optimum densities for both radars are shown to be ∼ 1.4 × 10⁵ cm^-3, ∼1.8 × 10⁵ cm^-3, and ∼2.0 × 10⁵ cm^-3 for winter, equinox, and summer, respectively. During daytime, optimum densities are larger by (0.2 - 0.3) × 10⁵ cm^-3. Observations at lower radar frequencies of ∼10 MHz show smaller required densities during nighttime, by ∼0.3 × 10⁵ cm^-3. Optimum electric fields for the moments of echo detection over RB are found to be 5-25 mV/m with no clear threshold effect and any seasonal dependence. The presented data suggest that for echo detection, favorable propagation conditions along the entire path of radio waves toward the scattering volume are important.