【摘要】 E层占优电离层(ELDI)是一种特殊的电离层垂直结构，表现出与偶发Es明显不同的时空分布和形态特征，但其形成机理尚不清楚.本文报道了发生在2001年7月15日的一次长持续时间(～2.3 h)的ELDI事件.地面雷达观测表明，该ELDI事件可以按照电子密度剖面不同的变化特征分为两个阶段.在第1个阶段里，E层密度大幅度增强而F层密度未有明显变化；在第2个阶段里，E层密度回落至正常水平而F层密度强烈耗空.卫星及其他地面设备的协同观测数据表明，高能离子沉降是ELDI第1阶段的主导形成机制，而强等离子体对流是第2阶段的主导机制.更多还原

【Abstract】 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 ～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.更多还原