Upwelling Coherent Backscatter Plumes Observed with Ionosondes in Low-Latitude Region

Investigations of upwelling backscatter plumes are mostly from observations of VHF radars. In this study, we report the first observation of upwelling backscatter plumes (backscatter echoes beyond the critical frequency of the F2 layer, foF2) recorded by ionosondes at low latitudes on 13 March, 2015. With a pair of ionosondes (Puer, 22.7o N, 101.05o E, Dip Lat 12.9o N, and Chiang Mai, 18.76o N, 98.93o E, Dip Lat 9.04o N), Swarm satellites flying side-by-side (longitudinal separation of about 1.4°, about 150 km), and an all-sky imager (25o N, 104o E, Dip Lat 15.1o N), the evolution of plasma bubbles is presented in this study. Observations show that ionosonde backscatter plumes originating from a local-scale upwelling could be observed. In addition, this study also reported ionosonde backscatter plumes from other regions with approaching and receding characteristics. Results show that characteristics of backscatter plumes with ionosondes are consistent with observations from VHF radars. It suggests that ionosonde backscatter plumes might be used to study characteristics of upwelling backscatter plumes as well.