L‐Band Synthetic Aperture Radar Observation of Ionospheric Density Irregularities at Equatorial Plasma Depletion Region

Abstract

Abstract Plasma density irregularities in the equatorial ionosphere are thought to cause the distortions of L‐band Synthetic Aperture Radar (SAR) images, which have been observed in recent years, but the origin of the image distortion has not yet been clearly identified experimentally. We report on the first simultaneous observation of equatorial plasma bubbles (EPBs) by the ALOS‐2/PALSAR‐2 satellite and ground 630‐nm airglow imager in northern Brazil. We observe stripe‐like distortions of SAR signal power that are aligned in the direction of local magnetic field lines. The stripe‐like patterns are observed in the vicinity of airglow depletion. The result shows that the observed L‐band SAR stripes are caused by ionospheric scintillation due to plasma irregularities with the scale size of hundreds of meters associated with EPBs. We show that the SAR scintillation stripes are predominantly found at the location of sharp density gradients in the two‐dimensional form.

Keywords

• all sky imager
• equatorial plasma bubble
• ionosphere
• plasma irregularities
• Synthetic Aperture Radar