@proceedings {836, title = {Possible Drivers of Large Scale Traveling Ionospheric Disturbances by Analysis of Aggregated Ham Radio Contacts}, year = {2024}, month = {03/2024}, publisher = {HamSCI}, address = {Cleveland, OH}, abstract = {

Large Scale Traveling Ionospheric Disturbances (LSTIDs) are quasiperiodic electron density perturbations of the F region ionosphere that have periods of 30 min to over 180 min, wavelengths of over 1000 km, and velocities of 150 to 1000 m/s. These are seen as long slow oscillations in the bottom side of the ionosphere in data from ham radio contacts at 20 meters wavelength on roughly a third of the days in a year. They might be triggered by electromagnetic forces from above, and/or by mechanical pressures from below. The explosion of the Tonga volcano on January 15, 2022 revealed that such a LSTID could be triggered by a violent updraft from the Earth{\textquoteright}s surface into the stratosphere and then detected in the ionosphere over the United States nine hours later. We consider other possible drivers such as the auroral electrojet, the polar vortex, thunderstorms, zonal wind speeds, gravity wave variances, and their time derivatives in 2017.

}, author = {Diego Sanchez and Mary Lou West and Nathaniel A. Frissell and Gareth W. Perry and William D. Engelke and Robert B. Gerzoff and Philip J. Erickson and J. Michael Ruohoniemi and Joseph B. H. Baker and V. Lynn Harvey} } @proceedings {637, title = {Potential Science Opportunities for HamSCI in Antarctica}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, address = {Huntsville, AL}, abstract = {

The maturation and proliferation of passive radio receivers based on software defined radio principles and architecture herald a new era of radio remote sensing in solar-terrestrial physics. Antarctica is a region of interest for deploying HF radio receivers for many reasons. The significant offset of the geographic and magnetic poles allows one to study multiple terrestrial magnetosphere-ionosphere-thermosphere regions of interest, e.g., the polar, auroral, and sub-auroral zones, using ground-based instruments. Additionally, the significant snow and ice coverage in Antarctica is a strong absorber of HF radio waves. This severely mitigates intracontinental multi-hop propagation modes, which may be advantageous for geolocating geophysical features detected by HF radio techniques, thereby improving remote sensing performance. In this poster presentation, we will analyze a case of a QSO between two operators, captured by a receiver located at McMurdo Station in Antarctica. We will discuss the signal characteristics of each transmission and pay particularly close attention to how variations in the CW transmissions may be linked to geophysical processes occurring in the region at the time. The overarching goal of this presentation is to incite discussion on how existing and future passive HF receiving systems in Antarctica can leveraged to advance not only the art of radio but solar-terrestrial physics in Antarctica.

}, author = {Gareth W. Perry and Nathaniel A. Frissell} } @proceedings {622, title = {Properties and Drivers of Plasma Irregularities in the High-Latitude Ionosphere Computed using Novel Incoherent Scatter Radar Techniques}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, address = {Huntsville, AL}, abstract = {

To provide new insights into the relationship between geomagnetic conditions and plasma irregularity scale-sizes, high-latitude irregularity spectra are computed using novel Incoherent Scatter Radar (ISR) techniques. This new technique leverages: 1) the ability of phased array Advanced Modular ISR (AMISR) technology to collect volumetric measurements of plasma density, 2) the slow F-region cross-field plasma diffusion at scales greater than 10 km, and 3) the high dip angle of geomagnetic field lines at high-latitudes. The resulting irregularity spectra are of a higher spatiotemporal resolution than has been previously possible with ISRs. Spatial structures as small as 20 km are resolved in less than two minutes (depending on the radar mode). In this work, we focus on Resolute Bay ISR observations operating in high-beam modes, such as the imaginglp mode. In addition to having an unprecedented view of the size and occurrence of irregularities as they traverse the polar cap, we find that near magnetic local noon the spectral power shifts to scales greater than 50 km, and from 15 to 5 magnetic local time the spectral power shifts to structures less than 50 km. This either reflects the role of polar cap convection in breaking down structures as they travel from the dayside ionosphere to the nightside, or the role of photoionization "smoothing" the dayside ionosphere. Additionally, during periods of enhanced geomagnetic conditions, such as periods with low AL indices, the spectral power shifts to structures 50 km and larger. This presentation will discuss these findings, as well as show seasonal variations.

}, author = {Lindsay V. Goodwin and Gareth W. Perry} }