Master of Science, Miami University, 2017, Computational Science and Engineering

The focus of this thesis is to characterize the variability of the helium ion fraction in the topside ionosphere using incoherent scatter radar (ISR) from Arecibo Observation, Puerto Rico. The thesis centers on two aspects: The first one is to present the phenomenon of helium ion fraction with solar cycle, season, and day-and-night. This study firstly reports the seasonal phenomenon of helium ion fraction from 400 km to 700 km in detail at solar maximum over Arecibo. The second one is to analyze the mechanism of seasonal phenomenon of helium ion fraction. The results show downward ion flow plays an important role in seasonal variation of the helium ion fraction.

Committee: Qihou Zhou (Advisor); Donald Ucci (Committee Member); Dmitriy Garmatyuk (Committee Member) Subjects: Electrical Engineering

Master of Science, Miami University, 2015, Computational Science and Engineering

Incoherent scatter radar (ISR) is a versatile tool to study the ionosphere by measuring the autocorrelation function (ACF). Accurate ACF in the E-region is difficult to obtain because the relative short range limits the length of a pulse. The short correlation time of the ionosphere renders the correlation using the pulse-to-pulse technique useless. In the thesis, we study a method that combines intra-pulse and inter-pulse techniques and apply it to the data taken at Arecibo Observatory. We show simultaneously measured ACF's at short and long lags and summarize the merits of ACF. Applications of ACF and its advantages are discussed. The technique used here will make the derivation of ionosphere parameters more accurate.

Committee: Qihou Zhou (Advisor); Chi-Hao Cheng (Committee Member); Dmitriy Garmatyuk (Committee Member) Subjects: Aeronomy; Aerospace Engineering; Computer Engineering; Computer Science; Earth; Radiology

Master of Science, Miami University, 2015, Computational Science and Engineering

D-region is the lowest part of the ionosphere, ranging from about 60 km to 90 km. This thesis uses incoherent scatter radar (ISR) data obtained from the Arecibo Observatory, Puerto Rico, to study the D-region structure and associated phenomena. We have described a methodology of the data processing. The thesis focuses on the relationship between ISR spectral width and ionospheric parameters in the D-region, such as ion temperature, ion-neutral collision frequency and ion mass. The effects that negative ions and Doppler broadening have on the ISR spectrum are discussed. A detailed discussion on the ion-mass and ISR spectral width is included in this study.

Committee: Qihou Zhou (Advisor); Chihao Cheng (Committee Member); Dmitriy Garmatyuk (Committee Member) Subjects: Electrical Engineering

Master of Science, Miami University, 2012, Computational Science and Engineering

Because of deficiencies in sampling resolution and storage space, the plasma line frequency component of the incoherent scatter radar (ISR) spectrum has been neglected in experimentally verifying ionospheric parameters. Several incoherent scatter theories were independently developed with confirmation from low resolution data in the 1960s that used the plasma line resonant frequency and plasma line peak intensity to derive ionospheric parameters. Now that higher resolution measurement techniques exist, this thesis investigates three methods for obtaining plasma line resonant frequency, peak intensity, and spectral width. Following this study, several salient features endemic to the ISR experiment performed on January 15-17th, and January 22nd of 2010 are presented and analyzed.

Committee: Qihou Zhou PhD (Advisor); Jade Morton PhD (Committee Member); Chi Hao Cheng PhD (Committee Member) Subjects: Aeronomy; Electrical Engineering; Plasma Physics

Master of Science, Miami University, 2012, Computational Science and Engineering

This thesis reports the investigation of the dynamics and associated phenomena occurring in the ionospheric E- and F-region heights above Arecibo. The observational data was derived with an incoherent scatter radar (ISR) from Arecibo Observatory, Puerto Rico. The thesis focuses primarily on two aspects. One is to study the atmospheric tidal and planetary waves. This is the first time that dual-beam ISR has been used for E- and F-region tidal and planetary wave studies. The vertical structures of the observed tidal and planetary waves are analyzed rigorously. This study is the first to report the existence and possible excitation mechanism of a terdiurnal tide in the F-region at low latitude. The second aspect is to give a more complete explanation of the midnight collapse phenomenon. The F-region electric field, ambipolar diffusion, and tidal components in the meridional wind all play a role in causing the midnight collapse at Arecibo.

Committee: Qihou Zhou PhD (Advisor); Jade Morton PhD (Committee Member); Dmitriy Garmatyuk PhD (Committee Member) Subjects: Aeronomy; Engineering