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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
The Impact Of Energetic Neutral Particles Raining Down On The Thermosphere Due To Charge Exchange Reactions In The Upper Ionosphere And Polar Wind, Larry Gardner
Funded Research Records
No abstract provided.
Microcontroller Differential Gps To Subtract Signal Delay Due To Ambient Free Electrons In The Ionosphere, Diana Jane Swanson
Microcontroller Differential Gps To Subtract Signal Delay Due To Ambient Free Electrons In The Ionosphere, Diana Jane Swanson
Physics
The goal of this project is to create a Global Positioning System (GPS) receiver that is more precise than one GPS receiver on its own. The technique is to take the difference between a GPS receiver’s measured position and its actual position, then use radio frequency (RF) communication to send that differential value to another microcontroller GPS receiver. This differential value will be added to the measured second location to get a more accurate position for the second GPS receiver, thus creating a differential GPS.
Effects Of The Hall Conductivity In Ionospheric Heating Experiments, B. Tulegenov, A. V. Streltsov
Effects Of The Hall Conductivity In Ionospheric Heating Experiments, B. Tulegenov, A. V. Streltsov
Publications
We investigate the role of Hall conductivity in ionospheric heating experiments. Ionosphericheating by powerful X-mode waves changes the Hall and Pedersen conductances in theEandDregions,which lead to the generation of ultra-low frequency (ULF)/extremely-low frequency/very low frequencywaves, when the electric field exists in the ionosphere. The importance of the Hall currents in themagnetosphere-ionosphere interactions, carried by ULF waves and field-aligned currents, has beenconsistently overlooked in studies devoted tothe active experiments. Simulations of the three-dimensionaltwo-fluid magnetohydrodynamic (MHD) model, presented in this paper, demonstrate that the Hallconductivity changes (1) the growth rate and the amplitude of ULF waves generated by the heating and (2)the …
Artificial Aurora Produced By Haarp, B. Tulegenov, A. V. Streltsov, E. Kendall, M. Mccarrick, I. Galkin
Artificial Aurora Produced By Haarp, B. Tulegenov, A. V. Streltsov, E. Kendall, M. Mccarrick, I. Galkin
Publications
We present results from the ionospheric heating experiment conducted at the HighFrequency Active Auroral Research Program (HAARP) facility, Alaska, on 12 March 2013. During theexperiment, HAARP transmitted in the direction of the magnetic zenith X-mode 4.57-MHz wave. Thetransmitted power was modulated with the frequency of 0.9 mHz, and it was pointed on a 20-km spot at thealtitude of 120 km. The heating (1) generates disturbances in the magnetic field detected with the fluxgatemagnetometer on the ground and (2) produces bright luminous spots in the ionosphere, observed with theHAARP telescope. Numerical simulations of the 3-D reduced magnetohydrodynamic (MHD) model revealthat these …
Ionospheric Signatures Of Acoustic Waves Generated By Transient Tropospheric Forcing, M. D. Zettergren, J. B. Snively
Ionospheric Signatures Of Acoustic Waves Generated By Transient Tropospheric Forcing, M. D. Zettergren, J. B. Snively
Matthew David Zettergren
Acoustic waves generated by tropospheric sources may attain significant amplitudes in the thermosphere and overlying ionosphere. Although they are weak precursors to gravity waves in the mesosphere below, acoustic waves may achieve temperature and vertical wind perturbations on the order of approximately tens of Kelvin and m/s throughout the E and F regions. Their perturbations to total electron content are predicted to be detectable by groundbased radar and GPS receivers; they also drive field-aligned currents that may be detectable in situ via magnetometers. Although transient and short lived, ionospheric signatures of acoustic waves may provide new and quantitative insight into …
Dynamics Of Density Cavities Generated By Frictional Heating: Formation, Distortion, And Instability, M. D. Zettergren, J. L. Semeter, H. Dahlgren
Dynamics Of Density Cavities Generated By Frictional Heating: Formation, Distortion, And Instability, M. D. Zettergren, J. L. Semeter, H. Dahlgren
Matthew David Zettergren
A simulation study of the generation and evolution of mesoscale density cavities in the polar ionosphere is conducted using a time-dependent, nonlinear, quasi-electrostatic model. The model demonstrates that density cavities, generated by frictional heating, can form in as little as 90 s due to strong electric fields of ∼120 mV/m, which are sometimes observed near auroral zone and polar cap arcs. Asymmetric density cavity features and strong plasma density gradients perpendicular to the geomagnetic field are naturally generated as a consequence of the strong convection and finite extent of the auroral feature. The walls of the auroral density cavities are …
Nonlinear Ionospheric Responses To Large-Amplitude Infrasonic-Acoustic Waves Generated By Undersea Earthquakes, M. D. Zettergren, J. B. Snively, A. Komjathy, O. P. Verkhoglyadova
Nonlinear Ionospheric Responses To Large-Amplitude Infrasonic-Acoustic Waves Generated By Undersea Earthquakes, M. D. Zettergren, J. B. Snively, A. Komjathy, O. P. Verkhoglyadova
Matthew David Zettergren
Numerical models of ionospheric coupling with the neutral atmosphere are used to investigate perturbations of plasma density, vertically integrated total electron content (TEC), neutral velocity, and neutral temperature associated with large-amplitude acoustic waves generated by the initial ocean surface displacements from strong undersea earthquakes. A simplified source model for the 2011 Tohoku earthquake is constructed from estimates of initial ocean surface responses to approximate the vertical motions over realistic spatial and temporal scales. Resulting TEC perturbations from modeling case studies appear consistent with observational data, reproducing pronounced TEC depletions which are shown to be a consequence of the impacts of …
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. …
Latitude And Longitude Dependence Of Ionospheric Tec And Magnetic Perturbations From Infrasonic-Acoustic Waves Generated By Strong Seismic Events, M. D. Zettergren, J. B. Snively
Latitude And Longitude Dependence Of Ionospheric Tec And Magnetic Perturbations From Infrasonic-Acoustic Waves Generated By Strong Seismic Events, M. D. Zettergren, J. B. Snively
Publications
A numerical study of the effects of seismically generated acoustic waves in the ionosphere is conducted using a three-dimensional (3-D) ionospheric model driven by an axisymmetric neutral atmospheric model. A source consistent with the 2011 Tohoku earthquake initial ocean surface uplifting is applied to simulate the subsequent responses. Perturbations in electron density, ion drift, total electron content (TEC), and ground-level magnetic fields are examined. Results reveal strong latitude and longitude dependence of ionospheric TEC, and of ground-level magnetic field perturbations associated with acoustic wave-driven ionospheric dynamo currents. Results also demonstrate that prior two-dimensional models can capture dominant meridional responses of …