On the Spatial Structure and Zonal Drift of Low Latitude E Region Irregularity Patches Over Hainan

Abstract

AbstractAll‐sky radar measurements provide a unique capability to resolve the spatial structure of E region irregularities over a large zonal region. With the all‐sky radar interferometry observations at Ledong (18.4°N, 109.0°E) in Hainan, China, the spatial structure and zonal drift of low latitude E region field‐aligned irregularities (FAIs) over a large region are statistically investigated for the first time. It is revealed that the E region FAIs, including both the continuous and quasi‐periodic (QP) types shown in radar range‐time‐intensity maps, occurred most frequently in summer. The continuous type was observed being generated locally without obvious zonal drift. The QP type generally covered ∼40–500 km zonally, and consisted of up to 9 (peaking at 3–4) FAI patches separated by ∼20–130 km (peaking at ∼60 km). The spatially separated FAI patches predominantly drifted westward at the speed ∼50–200 m/s. Besides the Kelvin‐Helmholtz instability, gravity waves were surmised to be a major source for causing the spatial structures of low latitude QP type E region FAIs. Neutral wind was suggested to play an important role for their zonal drifts.