Spaceborne L-band SAR imaging of high latitude plasma density irregularity under particle precipitation

Abstract

We present coordinated observations of the high latitude ionosphere simultaneously performed by L- band SAR satellite and incoherent scatter radar techniques. Small scale plasma density irregularity is studied by the Advanced Land Observation Satellite 2 L-band Synthetic Aperture Radar (SAR) and the European Incoherent Scatter (EISCAT) radar at Tromsø, Norway. Fine scale SAR imaging captured the horizontal distribution of image azimuth shift caused by Total Electron Content (TEC) gradients at enhanced ionization up to about 300 km height observed by the EISCAT UHF radar. The irregular electron density structure is characterized by sub-kilometer patches to tens of kilometer structures aligned in east-west direction. TEC gradients can be estimated by using single image SAR sub-band data. Results suggest that these observed structures are likely associated with density irregularities caused by precipitating electrons that cascaded into smaller scales by plasma instability processes. This study suggests that spaceborne SAR may achieve mapping of small scale TEC disturbances as a new ionospheric observation tool especially when combined with other measurements.