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Full-Text Articles in Physics
Global Ionosonde And Gps Radio Occultation Sporadic-E Intensity And Height Comparison, Joshua Y. Gooch
Global Ionosonde And Gps Radio Occultation Sporadic-E Intensity And Height Comparison, Joshua Y. Gooch
Theses and Dissertations
A global, multi-year comparison of low and mid-latitude COSMIC GPS radio occultation (RO) sporadic-E (Es) plasma frequency and altitude and Digisonde blanketing frequency (fbEs) and altitude within 150 km and 30 minutes of each other. RO methods used to estimate the intensity of the Es layer include the scintillation index S4, total electron content (TEC) with both a constant and variable Es cloud thickness, and an Abel transform. The S4 and TEC with varying thickness techniques both under-represent the fbEs values while the TEC with constant thickness and Abel transform better estimate Digisonde fbEs values. …
Impacts Of Sub-Auroral Polarization Streams On High Frequency Operations As A Function Of Modeled Particle Energy Flux, Nathan D. Smith
Impacts Of Sub-Auroral Polarization Streams On High Frequency Operations As A Function Of Modeled Particle Energy Flux, Nathan D. Smith
Theses and Dissertations
Space weather events can cause irregularities within the ionosphere; in particular, this research examines sub-auroral polarization streams (SAPS), as their accompanying irregularities and effects can degrade high-frequency (HF) signal propagation. It is known that the strongest westerly current drifts delineating SAPS are associated with a deep ionospheric trough, which in turn contaminates HF data with clutter from the non-standard ionosphere. Having a methodology to track and identify these occurrences on current computational architecture would provide operators enhanced situational awareness in knowing to expect degradation in HF processes. This study has discovered a weak, yet significant, exponentially decaying correlation between maximum …
Gps Phase Scintillation At High Latitudes During Geomagnetic Storms Of 7–17 March 2012 – Part 1: The North American Sector, P. Prikryl, R. Ghoddousi-Fard, E. G. Thomas, J. M. Ruohoniemi, S. G. Shepherd
Gps Phase Scintillation At High Latitudes During Geomagnetic Storms Of 7–17 March 2012 – Part 1: The North American Sector, P. Prikryl, R. Ghoddousi-Fard, E. G. Thomas, J. M. Ruohoniemi, S. G. Shepherd
Dartmouth Scholarship
During the ascending phase of solar cycle 24, a series of interplanetary coronal mass ejections (ICMEs) in the period 7–17 March 2012 caused geomagnetic storms that strongly affected high-latitude ionosphere in the Northern and Southern Hemisphere. GPS phase scintillation was observed at northern and southern high latitudes by arrays of GPS ionospheric scintillation and TEC monitors (GISTMs) and geodetic-quality GPS receivers sampling at 1 Hz. Mapped as a function of magnetic latitude and magnetic local time, regions of enhanced scintillation are identified in the context of coupling processes between the solar wind and the magnetosphere–ionosphere system. Large southward IMF and …
Ensemble Modeling With Data Assimilation Models: A New Strategy For Space Weather Specifications, Forecasts, And Science, Robert W. Schunk, Ludger Scherliess, V. Eccles, Larry Gardner, Jan Josef Sojka, L. Zhu, X. Pi, A. J. Mannucci, B. D. Wilson, A. Komjathy, C, Wang, G. Rosen
Ensemble Modeling With Data Assimilation Models: A New Strategy For Space Weather Specifications, Forecasts, And Science, Robert W. Schunk, Ludger Scherliess, V. Eccles, Larry Gardner, Jan Josef Sojka, L. Zhu, X. Pi, A. J. Mannucci, B. D. Wilson, A. Komjathy, C, Wang, G. Rosen
All Physics Faculty Publications
The Earth’s Ionosphere-Thermosphere-Electrodynamics (I-T-E) system varies markedly on a range of spatial and temporal scales and these variations have adverse effects on human operations and systems, including high-frequency communications, over-the-horizon radars, and survey and navigation systems that use Global Positioning System (GPS) satellites. Consequently, there is a need to elucidate the underlying physical pro- cesses that lead to space weather disturbances and to both mitigate and forecast near-Earth space weather.
Resolving Ionospheric E-Region Modeling Challenges: The Solar Photon Flux Dependence, Joseph B. Jensen, Jan J. Sojka, Michael David, Kent Tobiska, Robert W. Schunk, Tom Woods, Frank Eparvier
Resolving Ionospheric E-Region Modeling Challenges: The Solar Photon Flux Dependence, Joseph B. Jensen, Jan J. Sojka, Michael David, Kent Tobiska, Robert W. Schunk, Tom Woods, Frank Eparvier
Browse All Undergraduate research
The EVE instrument of the NASA Solar Dynamics Observatory (SDO) provides for the first time EUV and XUV measurements of the solar irradiance that adequately define the major source of ionization of the atmosphere. In our study we modeled the E-region of the ionosphere and analyzed how it is affected by the solar irradiance data obtained by EVE and contrast this with the S2000 Solar Irradiance model, used previously. The ionosphere has two major layers, the E-layer at 100 km, and the F-layer at 300 km. The difference in solar irradiances are small except at some wavelength bands, it is …
Resolving Ionospheric E-Region Modeling Challenges: The Solar Photon Flux Dependence, Joseph B. Jensen, Jan J. Sojka, Michael David, Kent Tobiska, Robert W. Schunk, Tom Woods, Frank Eparvier
Resolving Ionospheric E-Region Modeling Challenges: The Solar Photon Flux Dependence, Joseph B. Jensen, Jan J. Sojka, Michael David, Kent Tobiska, Robert W. Schunk, Tom Woods, Frank Eparvier
Student Showcase
No abstract provided.
Analysis Of Plasma Bubble Signatures In The Ionosphere, Omar A. Nava
Analysis Of Plasma Bubble Signatures In The Ionosphere, Omar A. Nava
Theses and Dissertations
Plasma bubbles are large scale structures of depleted plasma density in Earth's ionosphere that disrupt radio and satellite communications, to include global navigation satellite systems. This study used the Ionospheric Forecast Model (IFM) to analyze affected look angles and total electron content (TEC) differences due to plasma bubbles of various sizes for 27 geophysical conditions consisting of different seasons and levels of solar and geomagnetic activity at 421 GPS ground stations worldwide. Overall, different geographic locations and plasma bubble configurations produced different affected look angle profiles. Bigger plasma bubbles, larger density depletion factors, higher levels of solar activity and the …
Sensitivity Analysis Of Empirical Parameters In The Ionosphere-Plasmasphere Model, Janelle V. Jenniges
Sensitivity Analysis Of Empirical Parameters In The Ionosphere-Plasmasphere Model, Janelle V. Jenniges
Janelle V Jenniges
A sensitivity analysis of empirical parameters used in physics-based models was completed in this study to determine their effect on electron densities and total electron content (TEC) in the ionosphere. The model used was the Ionosphere- Plasmasphere Model (IPM) developed by Utah State University. The empirical pa- rameters studied include the O+/O collision frequency, zonal wind, secondary electron production, nighttime E⃗ × B⃗ drifts, and tidal structure. The sensitivity analysis was completed by comparing a default run of the IPM to a run with the parameter ad- justed for three geophysical cases. Many of the comparisons resulted in nonlinear changes …
A Validation Of The Parameterized Real-Time Ionospheric Specification Model (Prism) Version 1.7b, Shawn D. Filby
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, …