A Case Study of E‐Region Irregularities Associated With Sporadic E Layers Over Qujing

A distinct echo structure associated with E‐region field‐aligned irregularities (FAIs) was observed over Qujing (25.6°N, 103.7°E) on 19 May 2023 by a VHF coherent scatter radar. In the altitude–time–intensity (ATI) plot, the echoes exhibited pronounced quasi‐periodic features, and two different echo morphologies appeared after 23:30 LT on 19 May. The higher‐altitude echoes retained clear striation‐like structures, whereas the lower‐altitude echoes gradually evolved into a continuous descending layer. Simultaneously, ionosonde observations showed obvious increases in the Es‐layer critical frequency (foEs) and quasi‐periodic variations in the frequency spread Δf (ftEs − fbEs). Meteor radar observations showed strong and time‐evolving zonal wind shear in the 80–90 km altitude range, and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) temperature perturbation analysis indicated significantly enhanced gravity wave activity above 70 km on the same day. Furthermore, the Atmospheric Infrared Sounder (AIRS) satellite observations revealed intense convective activity in the troposphere southwest of Qujing, accompanied by a northeastward‐propagating brightness temperature perturbation pattern. These results suggest that the background winds modulated by the gravity waves generated by the deep convection in the troposphere played an important role in driving Es layer structuring and E‐region FAI generation in the ionosphere.