Multi-frequency scintillation in the Polar Cap

Amplitude and phase fluctuations in radio signals passing through the polar cap ionosphere occur frequently and can often be associated with high density patches of plasma that separate from the dayside ionosphere and become entrained in polar convection. These patches are susceptible to a range of fluid-like instabilities such as gradient drift instability (GDI) that result in production of hundreds of meters to tens of kilometers scale sized density irregularities that cause refraction and diffraction of ionospheric radio waves. Amplitude scintillation occurs where there are ionospheric structures close to the Fresnel scale, which itself depends on the frequency of the signal and height of the irregularities. By considering scintillation from different frequencies, we can intuit information about the scales in the underlying plasma structuring. However, multi-frequency radio experiments are not commonplace in polar regions and so, to date, we have only sparse details about irregularity spectrum and evolution. This work presents recent incoherent scatter radar and multi-frequency beacon measurements of ionospheric scintillation covering a range of ionospheric structures from tens of kilometers to a few hundred meters in scale observed near the Resolute Bay Observatory (RBO). Ionospheric scintillation signatures are compared for VHF, UHF, and L-band different frequencies to identify similar and dissimilar examples. Ionospheric scintillation data is obtained from the Canadian High Arctic Ionospheric Network (CHAIN) and the Coherent Electromagnetic Radio Tomography (CERTO) receivers. A statistical analysis of satellite conjunctions is performed with CHAIN and CERTO. Histograms of VHF, UHF, L-band phase and amplitude scintillation indices are created and interpreted within the context of plasma instability mechanisms and polar ionospheric dynamics.