认识与揭示电离层复杂的时空变化一直是电离层物理的重要研究方向之一。本项目拟利用北斗同步卫星电离层观测优势，结合测高仪、地磁等观测手段和数值理论模式，聚焦东亚扇区中低纬度电离层咬食现象的特征规律，探究电离层总电子浓度和峰值密度咬食特征的异同，厘清其纬度依赖性与区域性经度变化，甄别电离层电动力学、光化学等在其形成过程中相对贡献并揭示其物理机制。该项目将有利于认识我国上空电离层的区域特征，为提高空间天气预报能力服务。

Recently, the ionospheric total electron content (TEC) associated with the geostationary (GEO) satellites from Beidou system has good capability to capture the ionospheric variations, given that it is not contaminated by the spatial variations due to GNSS satellite motion. In this proposal, we focus on the ionospheric bite-out, a typical ionospheric variation that frequently occurs around the noontime in the low- and mid-latitudes. Based on GEO TEC observations as well as the ionosonde and magnetometer observations and theoretical models, we will conduct a systematical investigation of the ionospheric bite-out from the TEC and NmF2, and examine the latitudinal and regional longitudinal dependence of the ionospheric bite-out in the East Asia sector. We will also investigate the underlying physical processes of the ionospheric bite-out, and explore the relative contributions associated with the ionospheric electro-dynamics and photo-chemistry processes. This project will help to improve our understanding of ionospheric characteristics over China and East Asia region.