Case study of a long-lasting E-layer dominated ionosphere event

The E-layer dominated ionosphere (ELDI) is a special ionospheric vertical structure with quite different temporal and spatial distributions and morphological characteristics from the sporadic E layer (Es). However, its formation mechanism has not been well explained. This paper reports an ELDI event with long duration of similar to 2. 3 h on July 15, 2001. The ELDI event can be divided into two stages according to the electron density profiles shown by the ground-based radar observation. In the first stage, the electron density of E layer showed great increase while the electron density of F layer remained unchanged. In the second stage, the electron density of E layer felt back to normal level, while the electron density of F layer showed great depletion. Based on the coordinated satellite and other ground-based observations, we conclude that for this ELDI event, energetic ion precipitation is the dominant mechanism in the first stage, and strong plasma convection is the dominant mechanism in the second stage.