Incoherent scatter radar detection of enhanced plasma line in ionospheric E-region over Arecibo

Abstract

A series of incoherent scatter radar (ISR) observation were conducted at the Arecibo Observatory from December 27, 2005 until January 3, 2006. From plasma line measurements that were taken during this radar campaign, we found that plasma line enhancement was quite frequently seen in the ionospheric E-region. We hypothesized that the E-region plasma line enhancement over Arecibo was caused by precipitated electrons from the radiation belts. The precipitated electrons will enhance the population of suprathermal electrons in the E-region. Subsequently, suprathermal electrons will cause excitation of Langmuir waves that could be detected by incoherent scatter radar as plasma lines. In this thesis, we are going to examine and discuss the observed features of E-region plasma line enhancement over Arecibo to test this hypothesis. In addition, a theoretical discussion on Langmuir waves is also presented in a chapter of this thesis. Finally, we also introduce the Spread F Index (SFI) as a convenient bookkeeping method to summarize spread F condition over a certain period of time.