Imaging coherent backscatter radar observations of topside equatorial spread F

Abstract

Multiple baseline interferometric imaging of a large-scale topside spread F depletion has been performed at the Jicamarca Radio Observatory near Lima, Perú. A new imaging technique makes it possible to examine the detailed structure of the scatter from field-aligned irregularities in and around the depletion. A new antenna at Jicamarca, physically separated from the main antenna array, provided very long interferometry baselines up to ̃94 λ long for the observations. High-resolution images of coherent backscatter from the radar plume were computed from the interferometry data using the maximum entropy method. These images show that scattering regions with small Doppler velocities lay mainly along the boundary of the depleted region. Meanwhile, regions with high Doppler velocities were located within the depletion itself and could be seen convecting upward through the depleted channel.