Theory of Kilometric Gradient-Drift Structures in the Daytime and Nightime Equatorial Electrojet

这一建议包括使用本征模和初值方法对线性不稳定谱进行彻底的探索，以及由这些不稳定的非线性增长所导致的二维湍流。PI将使用测量的密度和电场分布。他将试图阐明短波不稳定性在存在占主导地位的千米级结构时的作用，以及高空电喷流在白天和夜间的湍流特征的区别。最后，他将确定(1)速度切变的作用，它在抑制短波不稳定性方面比长波不稳定性要有效得多，以及(2)速度切变的自我调节作用，不仅由周围的电场和中性风驱动，而且可能是由短波长处的湍流雷诺应力所产生的发电机效应所产生的。

This proposal includes a thorough exploration of the linear instability spectrum, using both eigenmode and initial-value methods, and the two dimensional turbulence that results from the nonlinear growth of these instabilities. The PI will use measured density and electric field profiles. He will attempt to clarify the role of short-wavelength instabilities in the presence of dominant kilometer-scale structures, the distinctions in turbulent characteristics between the upper electrojet in daytime as well as nighttime. Finally, he will ascertain (1) the role of velocity shear, much more effective in damping short-wavelength instabilities than long-wavelength ones, and (2) the self- regulatory role of velocity shear, not only driven by the ambient electric fields and neutral wind, but also possibly generated by a dynamo effect due to the turbulent Reynolds stress at short wavelengths.***