Three‐dimensional nonlinear simulations of the gradient drift instability in the high‐latitude ionosphere
Three‐dimensional nonlinear simulations of the gradient drift instability in the high‐latitude ionosphere
复制标题
高纬度电离层梯度漂移不稳定性的三维非线性模拟
DOI：
--
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
S. Basu
中科院分区：
文献类型：
--
作者：
P. Guzdar;N. Gondarenko;P. Chaturvedi;S. Basu
针对代表极帽等离子体片的二维平衡密度梯度，给出了梯度漂移不稳定性（GDI）的非线性三维（3-D）模拟。结构的等离子体补丁的整体演变的影响显着的动态所造成的影响，平行于地磁场。长波长（kLn ≤ 1）在三维情况下是强稳定的，并且非线性状态由较小的介观尺度（kLn>> 1）主导（其中k和Ln分别是模式数和密度梯度尺度长度）。这些结果为高纬电离层的观测提供了一种解释，表明在行星际磁场（IMF）BZ向南和极冠上空盛行反向阳对流时，产生了与极冠斑块相关的中尺度不规则性。观察到极盖斑块在经历结构化的同时保持其独特的身份，并进行远距离（~ 3000公里）的对流。因此，我们在这里建议，包括三维效应是成功解释高纬度不规则性的关键，也是可信模拟这些过程的先决条件。
Nonlinear three‐dimensional (3‐D) simulations of the gradient drift instability (GDI) are presented for a two‐dimensional equilibrium density gradient representing a polar cap plasma patch. The overall evolution of structuring of the plasma patch is influenced markedly by the effects caused by dynamics parallel to the geomagnetic field. The long wavelengths (kLn ≤ 1) are strongly stabilized in the 3‐D case, and the nonlinear state is dominated by smaller mesoscales (kLn » 1) (where k and Ln are the mode number and density gradient scale length, respectively). The results provide an interpretation to the observations at the high‐latitude ionosphere indicating a generation of mesoscale irregularities associated with the polar cap patches when the interplanetary magnetic field (IMF) BZ is southward and antisunward convection prevails over the polar cap. The polar cap patches are observed to convect to large distances (∼3000 km) undergoing structuring while maintaining their distinct identity. Thus we suggest here that the inclusion of three‐dimensional effects is key to a successful interpretation of high‐latitude irregularities, as well as a prerequisite for a credible simulation of these processes.