Collaborative Research: Causes and Consequences of the Gradients in the Vertical Plasma Drift in the Equatorial Plasma Drift Vortex

Space Environment Corporation, Logan UT

Investigators

Abstract

At low latitudes during the evening twilight period, as the E-region plasma recombines due to fast chemistry, a strong vertical gradient in the plasma density will appear below the F-region peak height. This vertical drift gradient in altitude below the F peak can be surprising large, dynamic, and variable from day-to-day. This award would apply a physics-based model of the ionosphere-thermosphere-electric field to study the relationship between the development of these vertical gradients and a possible production of plasma bubble structure. In these circumstances the phenomenon of unstable plasma fluids that occur whenever a dense fluid overlies a light fluid will generate strange three-dimensional structures. These plasma depletion regions (often called "bubbles") affect severely communications of radio waves that normally are reflected off the smooth bottom side of the F-region plasma layer. The data that would be used in this study are derived from observations by the Jicamarca Radio Observatory and by the Low Latitude Ionosphere Sensor Network (LISN) network of total electron content and ionosonde measurements of plasma density throughout South America. Also associated with LISN data are equatorial magnetometer measurements that can be interpreted to produce estimates of upward vertical plasma drift rates during the evening period. These results would be used to explore the day-to-day variability of the gradients to help develop a better understanding of the relationship between the rate of vertical drift and the onset of equatorial plasma bubble production. UTD will be utilizing a graduate student to accomplish much of the data analysis and modeling. Large equatorial plasma bubbles (EPBs), which are associated with the strongest signal scintillations, have negative impacts on communication and navigation technologies. Society has become dependent on these technologies to accomplish common tasks in transportation services, industrial ventures, and military operations. In addition to addressing these important science questions for the mitigation of negative impacts of F-region plasma structures, these activities will continue and expand multinational collaborations associated with the LISN Project and the JRO.