On the spatial relationship of 1‐meter equatorial spread‐F irregularities and depletions in total electron content

An experiment was conducted at Kwajalein AtollMarshall Islands to investigate the spatial relationship of 1‐m equatorial spread‐F irregularities to total electron content (TEC) depletions. A high‐power radar was operated (1) in a backscatter scan mode to spatially map the distribution of 1‐m irregularitiesand (2) in a dual‐frequencysatellite‐track mode to obtain the longitudinal TEC variations. We show that radar backscatter “plumes” found in the disturbednighttime equatorial ionosphere are longitudinally coincident with TEC depletions. We suggest that the TEC depletions are probably due to the presence of plasma “bubbles” in the equatorial F layer.