Modeling of Three-Dimensional Structure and Dynamics of the Large-Scale Sporadic E Layers Over East Asia

Abstract

Sporadic E (Es) layers are thin layers of concentrated metallic ions in the mesosphere and lower thermosphere region. Their occurrence can cause the uneven distribution of plasma density and affects the performance of the Global Navigation Satellite System and high/very high frequency radio communications. Currently, the three-dimensional (3-D) Es layer structure and evolution process have not yet been fully understood. Using the Fe⁺ layer as a proxy for Es layer, in this study, we investigated the structural and dynamic characteristics of the large-scale Es layers extending thousands of kilometers over East Asia by using a 3-D Es layer numerical model driven by neutral winds from the Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension model. The simulation results show that the Es layer is a tilted blanket rather than a narrow flat band. In addition, the Es layers mainly occur in the 3-D spatial position of the convergent vertical wind shear. The apparent horizontal velocity (∼300–400 m/s) of Es structure is mostly westward and northward, which is different from the ion drift velocity (∼100 m/s). This indicates that Es structure can develop rapidly over a large area simultaneously rather than only drifting from one location to the next. This study systematically analyzed the physics of the 3-D Es layer, which can be helpful for understanding the Es horizontal structure and dynamics recorded by different instruments, such as satellites and global navigation satellite system receiver networks.