Engineering Physics Commons^™

Numerical Analysis And Theory Of Oblique Alfvenic Solitons Observed In The Interplanetary Magnetic Field, Harry Raphael Wheeler Iv

Doctoral Dissertations and Master's Theses

Recently, there have been reports of small magnetic pulses or bumps in the interplanetary magnetic field observed by various spacecraft. Most of these reports claim that these localized pulses or bumps are solitons. Solitons are weakly nonlinear localized waves that tend to retain their form as they propagate and can be observed in various media which exhibit nonlinear steepening and dispersive effects. This thesis expands the claim that these pulses or bumps are nonlinear oblique Alfven waves with soliton components, through the application of analytical techniques used in the inverse scattering transform in a numerical context and numerical integration of …

Effect Of Storm Enhanced Densities On Geo-Location Accuracy Over Conus, Lindon H. Steadman

Theses and Dissertations

Storm enhanced densities (SEDs) are ionospheric plasma enhancements that disrupt radio communications in the near-Earth space environment, degrading the Global Positioning System (GPS) and other key technologies. Accurate GPS/total electron content (TEC) correction maps produced by ionosphere models can mitigate degradations from SEDs. An artificial SED was created and ingested via slant TEC measurements into the Global Assimilation of Ionospheric Measurements Gauss-Markov Kalman Filter Model to determine how many ground GPS receivers are needed to produce reliable GPS/TEC correction maps over the continental United States during geomagnetic storming. It was found that 110 well-positioned GPS receivers produced the best overall …

Fabry-Perot Observations Of Midlatitude Neutral Winds And Atmospheric Gravity Wave Activity, Marjory Anne Katon

Doctoral Dissertations and Master's Theses

The mesosphere and lower thermosphere displays a wide range of dynamical phenomena resulting in a complex and variable regions. Governed primarily by fluid dynamics, the motion of the upper atmosphere is modulated by a number of atmospheric waves propagating upward from various sources in the lower atmosphere. Among these are atmospheric gravity waves which have been recognized as a major source of momentum and energy in the mesosphere and lower thermosphere as well as a major factor in the dynamic coupling between the troposphere and lower thermosphere. A Fabry-Perot interferometer possessed by the Space Physics Research Laboratory at the Embry-Riddle …

Mitigation Of Water Vapor Interference For Infrared Polarization-Modulated Gas Filter Correlation Radiometry, David K. Lockwood

Electrical & Computer Engineering Theses & Dissertations

Gas filter correlation radiometry (GFCR) is a high-resolution, high-specificity technique for sensing gaseous species. A variation of absorption spectroscopy, GFCR has a long-proven record on orbital platforms for quantitative measurements of atmospheric constituents, as well as common usage in ground-based sensing applications. PMGFCR (Polarization-modulated GFCR) is a recent refinement of the technique with several advantages over the traditional method, including reducing the number of photodetectors required, increased sensitivity, and elimination of moving parts.

To date, no infrared remote sensors have successfully measured nitric oxide (NO) in vehicle exhaust due to spectral overlap by strong water vapor (H₂O_{v …}

Spectral And Temporal Characterization Of High Temperature Events, William F. Bagby

Theses and Dissertations

The remote observations of the temporal and spectral characteristics of the infrared (IR) emissions from exploding ordnance have been correlated with explosion conditions. A Bomem MR-154 Fourier Transform Interferometer with two detectors, InSb and HgCdTe, was used to record spectra in the 1.3 - 20 micrometers range. Data was collected at spectral resolutions of 16/cm and 4/cm, and temporal resolutions of 0.045 sand 0.123 5, respectively. The data files range in size from 900 Kilobytes to several Megabytes. These are reduced to 2-dimensional representations of temporal features that are less than 100 Kilobytes. The data analysis indicates the possibility of …

Wavelength Modulation Spectroscopy Of Water Vapor And Line Center Stabilization At 1.462 Μm For Lidar Applications, Colleen Marie Fitzgerald

Electrical & Computer Engineering Theses & Dissertations

Wavelength modulation spectroscopy was employed to investigate water vapor absorption lines in the 1.462 µm wavelength region using an external-cavity diode laser. These measurements were necessary in the development of a lidar (light detection and ranging) instrument for differential absorption measurement of the concentration and movement of water vapor in the Earth's atmosphere. Differential absorption measurements require that the laser frequency remain stable throughout the duration of the measurement. To ensure this stability, the laser output wavelength is monitored and a feedback control loop set up to minimize laser line drift. Three lines were investigated in the 1.462 µm region. …

Validation Of The Ionospheric Forecast Model (Ifm) Version 3, Michael D. Scott

Theses and Dissertations

The purpose of this research was to validate the Ionospheric Forecast Model (IFM) Version 3 to assess its suitability and usefulness as an operational tool. The Ionospheric forecast model is a first principles computer model designed to forecast the state of the global ionosphere to 24 hours. The scope was limited to a comparison of the F2 layer critical frequency (foF2) and peak electron density (hmF2) against observed ionosonde data. The model was run with global solar and geomagnetic indices and Information from Digitial Ionospheric Sounding System (DISS) observations as inputs. The DISS observations were input through the Parameterized Real-Time …

Fiber-Optic Coupled Lidar Receiver System To Measure Stratospheric Ozone, David Brent Harper

Electrical & Computer Engineering Theses & Dissertations

A fiber-optic coupled lidar receiver system was constructed to determine ozone concentrations in the stratosphere. The system was used to make ground-based measurements of lidar returns from a UV DIAL system. A fiber-optic cable was used to couple the light from the receiver telescope to the light detector. Photon counting was implemented as the light detection technique. This technique allowed detection of 301 and 311 nm lidar returns up to 27.5 and 32.5 km respectively. A software application was developed to control the photon counting system and perform real-time data analysis of measured lidar returns. DIAL measurements of stratospheric ozone …

A Validation Of The Parameterized Real-Time Ionospheric Specification Model (Prism) Version 1.7b, Shawn D. Filby

Theses and Dissertations

The most current version of the Parameterized Real-time Ionospheric Specification Model (PRISM), version 1.7b, was validated using Digital Ionospheric Sounding System (DISS) measurements of F2 layer critical frequency (foF2) and F2 peak electron density height (hmF2) as the "ground truth." PRISM was executed, first, with no real-time input parameter and, second, with Global Positioning System (GPS) Total Electron Content (TEC) measurements as the sole real-time parameter. Hourly values of hmF2 and foF2 over 123 days in 1994-1996 (solar minimum conditions) and covering three seasons (equinox, summer solstice, and winter solstice) were compared for Wallops Island, Virginia, and Point Arguello, California, …