Intermediate scale plasma density irregularities in the polar ionosphere inferred from radio occultation

Abstract:

In this research, we report intermediate scale plasma density irregularities in the high-latitude ionosphere inferred from
high-resolution radio occultation (RO) measurements in the CASSIOPE (CAScade Smallsat and IOnospheric Polar Explorer) - GPS
(Global Positioning System) satellites radio link. The high inclination of the CASSIOPE satellite and high rate of signal reception
by the occultation antenna of the GPS Attitude, Positioning and Profiling (GAP) instrument on the Enhanced Polar Outflow Probe platform
on CASSIOPE enable a high temporal and spatial resolution investigation of the dynamics of the polar ionosphere, magnetosphere-ionosphere
coupling, solar wind effects, etc. with unprecedented details compared to that possible in the past.

We have carried out high spatial resolution analysis in altitude and geomagnetic latitude of scintillation-producing plasma density
irregularities in the polar ionosphere. Intermediate scale, scintillation-producing plasma density irregularities,
which corresponds to 2 to 40 km spatial scales were inferred by applying multi-scale spectral analysis on the RO phase delay measurements.
Using our multi-scale spectral analysis approach and Polar Operational Environmental Satellites (POES) and
Defense Meteorological Satellite Program (DMSP) observations, we infer that the irregularity scales and
phase scintillations have distinct features in the auroral oval and polar cap regions. In specific terms, we found that
large length scales and and more intense phase scintillations are prevalent in the auroral oval compared to the polar cap region.
Hence, the irregularity scales and phase scintillation characteristics are a function of the solar wind and the magnetospheric forcing. Multi-scale analysis may become a powerful diagnostic tool for characterizing how the ionosphere is dynamically driven by these factors.