Imaging High-Latitude Plasma Density Irregularities Resulting from Particle Precipitation: Spaceborne L-Band SAR and EISCAT Observations

Abstract

High-latitude, small-scale plasma density irregularities are observed by the Advanced Land Observation Satellite 2, Phase Array type L-band Synthetic Aperture Radar-2 and the European Incoherent Scatter radar in Tromsø, Norway. Under high levels of ionization of up to approximately 300 km in height triggered by nighttime particle precipitation, high-resolution SAR images detect horizontal distributions of azimuth shifts resulting from the spatial gradients of electron density. The irregular electron density is characterized by tens of kilometers of band-like structures aligned in the east–west direction with small patch-like structures. We present a method for estimating the local change of TEC gradient and the height of ionospheric irregularities by using single-image SAR sub-band data. The results suggest that these observed structures are likely to be associated with density irregularities caused by precipitating electrons that may have been cascaded into smaller scales by plasma instability processes at F region altitudes. This study presents the first coordinated observations of high-latitude ionosphere features by using SAR satellites and incoherent scatter radar.