Physics Commons^™

Design And Characterization Of A Time-Of-Flight Mass Spectrometer For Composition Measurements In The Upper Atmosphere, E. Addison Everett

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The mesosphere/lower thermosphere (MLT) is perhaps the least understood region of Earth's atmosphere. Too high for balloons and winged aircraft, yet too low for satellites, direct access to the MLT to make in-situ measurements is via high-speed sounding rockets for brief periods of at most a few minutes. Mass spectrometers have previously been used to make composition measurements in this region. But, mass spectrometry in the MLT is difficult, mainly due to the ambient pressures here and also the high speeds and short flight durations of sounding rocket missions. Time-of-flight mass spectrometers (TOF-MS) are capable of making fast, accurate measurements …

Lunar Tidal Effects In The Electrodynamics Of The Low-Latitude Ionosphere, Brian David Tracy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In order to model and perform better forecasts of the upper atmosphere, we have studied variations in the equatorial ionosphere due to lunar tidal forcing. We used extensive measurements made by the Jicamarca Unattended Long-Term Investigations of the Ionosphere and Atmosphere (JULIA) and Incoherent Scatter Radar (ISR) systems at Jicamarca, Peru during geomagnetic quiet conditions to determine the season, local time, and lunar age-dependent lunar tidal effects on equatorial vertical plasma drifts. The amplitudes and phases of the semimonthly and monthly lunar tidal perturbations were derived using a least squares method. Our results indicate that, as expected, lunar tidal effects …

Surface Morphology Implications On Langmuir Probe Measurements, Padmashri Suresh

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Langmuir probes are extensively employed to study the plasmas in space and laboratory environments. Successful measurements require a comprehensive modeling of both the plasma environment and the probe conditions in the form of current collection models. In this thesis, the surface morphology implications on the probe current collection are investigated. This problem is applied and solved in the context of a CubeSat regime. The first problem that is investigated is the consequence of surface structural variability on the current measurements. A new model for dealing with non-uniformity of the probe surface structure is developed in this paper. This model is …

Dynamics Of Equatorial Spread F Using Ground-Based Optical And Radar Measurements, Narayan P. Chapagain

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Earth's equatorial ionosphere most often shows the occurrence of large plasma density and velocity fluctuations with a broad range of scale sizes and amplitudes. These night time ionospheric irregularities in the F-region are commonly referred to as equatorial spread F (ESF) or plasma bubbles (EPBs). This dissertation focuses on analysis of ground-based optical and radar measurements to investigate the development and dynamics of ESF, which can significantly disrupt radio communication and GPS navigation systems. OI (630.0 nm) airglow image data were obtained by the Utah State University all-sky CCD camera, primarily during the equinox period, from three different longitudinal …

Statistical Analysis Of The Usu Lidar Data Set With Reference To Mesospheric Solar Response And Cooling Rate Calculation, With Analysis Of Statistical Issues Affecting The Regression Coefficients, Troy Alden Wynn

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Though the least squares technique has many advantages, its possible limitations as applied in the atmospheric sciences have not yet been fully explored in the literature. The assumption that the atmosphere responds either in phase or out of phase to the solar input is ubiquitous. However, our analysis found this assumption to be incorrect. If not properly addressed, the possible consequences are bias in the linear trend coefficient and attenuation of the solar response coefficient.

Using USU Rayleigh lidar temperature data, we found a significant phase offset to the solar input in the temperatures that varies ±5 years depending on …

Investigating Small-Scale Dynamical Features In The Mesopause Region, Deepak B. Simkhada

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Utilizing analyses of observational data, we performed a detailed study to investigate short-period atmospheric gravity waves and ripples, and instabilities in the mesopause region. Recent coordinated measurements from Haleakala Observatory, Maui, HI via airglow wave imaging, meteor wind radar, and Na wind temperature lidar have provided a unique dataset for this study. Gravity waves generated in the lower atmosphere propagate energy upwards into the mesosphere and lower thermosphere region where they modulate the airglow emissions, and later break and deposit their momentum, causing significant perturbations in winds and temperatures. Ripples, on the other hand, are likely generated by localized shear …

Modeling The Electrodynamics Of The Low-Latitude Ionosphere, Christian Stephen Wohlwend

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The electrodynamics of the Earth's low-latitude ionosphere is dependent on the ionospheric conductivity and the thermospheric neutral density, temperature, and winds present. This two-part study focused on the gravity wave seeding mechanism of equatorial plasma depletions in the ionosphere and the associated equatorial spread F, as well as the differences between a two-dimensional flux tube integrated electrodynamics model and a three-dimensional model for the same time period. The gravity wave seeding study was based on a parameterization of a gravity wave perturbation using a background empirical thermosphere and a physics-based ionosphere for the case of 12 UT on 26 September …