CEDAR Postdoc: Nonlocal Effects in the Equatorial and Auroral Electrojet

Cornell University, Ithaca NY

Investigators

Abstract

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.