CEDAR Postdoc: Nonlocal Effects in the Equatorial and Auroral Electrojet

本研究的目的是研究高纬度E地区缓慢增长的不规则性，这些不规则性不能用局部线性不稳定来准确描述，而是具有对流的非局部演化。这项研究将利用现有的非局地模式从高纬度地区扩展到中低纬度地区。该模型基于等离子体微扰方程的扩展，并遵循波动作用守恒原理。在高纬度地区，先前使用该模型的研究已经揭示了一种新的机制，即当波传播到不同背景等离子体密度的区域时，波的增长或衰减纯粹来自波能量守恒。在大多数情况下，这一过程比传统的梯度漂移生长更为重要。在低纬度地区，极化漂移导致不规则性通过垂直等离子体密度梯度垂直传播，波能守恒原理的增长即使不是主导过程，也将是一个重要的过程。本研究将研究这一过程，并通过将模型推广到低纬度和中纬度的磁场几何形状，从总体上提高对E区不规则性演化的理解。此外，该模型的不稳定性模拟将与Jicamarca射电天文台的数据进行比较。这将有助于理解和解释E区不规则的雷达观测。赤道电喷流中的等离子体不规则性很重要，因为它们改变了输运性质，影响了E区的平均状态，改变了电喷流，并影响了整个中低纬度地区的电动力学。这些不规则性还提供了测量赤道MLT区域的电场和风等参数的手段，这些参数是其他方法无法轻易探测到的。随着我们对工作中的不稳定过程的理解的增长，这种测量的有效性也在提高。最后，对自然产生的等离子体波和不稳定性的研究对社会最终可能依赖作为能源的受限实验室等离子体的研究具有重要的意义。

The purpose of this study is to investigate slowly growing irregularities in the high latitude E region that cannot be described accurately by a local linear instability, but instead have a convective, nonlocal evolution. The study will make use of an extension of an existing nonlocal model from high latitudes to mid and low latitudes. The model is based on an expansion of the plasma perturbation equation, along with the principle of conservation of wave action. At high latitudes, previous research using this model has uncovered a new mechanism for wave growth or decay purely from conservation of wave energy, when a wave propagates into a region of different background plasma density. This process proved to be more important than traditional gradient drift growth in most cases. At low latitudes, where the polarization drift causes irregularities to propagate vertically through the vertical plasma density gradient, growth from the principle of conservation of wave energy will be an important, if not dominant process. This research will investigate the process, and in general improve the understanding of the evolution of E region irregularities, by generalizing the model to the magnetic field geometry at low and mid latitudes. Additionally, instability simulations from the model will be compared with Jicamarca Radio Observatory data. This will help understanding and interpretation of radar observations of E region irregularities. Plasma irregularities in the equatorial electrojet are important because they modify transport properties and affect the mean state of the E region, altering the electrojet current, and influencing electrodynamics throughout low and mid latitudes. The irregularities also provide means of measuring parameters like electric fields and winds in the equatorial MLT region that cannot be readily probed in other ways. The validity of such measurements improves as our understanding of the instability processes at work grows. Finally, the study of naturally occurring plasma waves and instabilities has important overtones for research in confined laboratory plasmas that society may eventually depend upon as energy sources.