Examining the ionospheric sources of reduced coherence streaks in L-band SAR interferograms at high-latitudes

L-band (1–2 GHz) signals used in space based radar and communication systems are sensitive to ionospheric plasma irregularities, which can lead to azimuth focusing errors and small image shifts in synthetic aperture radar (SAR) imagery due to density structures ranging from meters to kilometer scale.
Interferograms derived from Phased Array L-band Synthetic Aperture Radar (PALSAR) onboard the Advanced Land Observing Satellite (ALOS) occasionally exhibit narrow azimuth-aligned streaks of reduced coherence, particularly at high latitudes. These features, here referred to as ionospheric azimuth streaks, are believed to be associated with total electron content (TEC) gradients and plasma density irregularities
in the high-latitude ionosphere, but their physical drivers and relation to ionospheric dynamics remain poorly understood. Previous studies have been limited to particle precipitation and use of GNSS. In this
study, we investigate the connection between these ionospheric azimuth streaks and ionospheric density irregularities using conjunction events between ALOS/PALSAR observations, EISCAT UHF ground
based radar, and in-situ measurements from the Swarm satellite constellation. By combining SAR interferometric reduced coherence patterns with EISCAT radar and Swarm measurements of plasma density, we aim to identify the ionospheric conditions associated with the formation of ionospheric azimuth streaks. This multi-instrument approach provides a unique opportunity to link remote sensing signatures
in SAR interferograms with in-situ observations of ionospheric density structures. This work aims to improve the understanding of ionospheric impacts on L-band SAR observations and contribute to better
characterization of small scale plasma irregularities in the high latitude F region ionosphere.