@proceedings {970, title = {Southern Hemisphere MSTID response to a Sudden Stratospheric Warming Observed by the Falkland Islands SuperDARN Radar}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, abstract = {

We present a study of Medium Scale Traveling Ionospheric Disturbances (MSTIDs) observed by the Falkland Islands Radar (FIR) in the Southern Hemisphere in response to a sudden stratospheric warming (SSW) event. MSTIDs are quasi-periodic variations in the upper atmospheric (~250 km altitude) plasma with phase speeds of ~100-250 m/s, periods from ~15-60 minutes, and horizontal wavelengths of several hundred kilometers. Daytime MSTIDs are known to be associated with gravity waves (GWs) that originate in the lower and middle atmosphere and propagate upward into the F-region. Neutral wind filtering of these GWs creates a strong dependence of GW-associated MSTIDs on stratospheric and mesospheric zonal wind direction and speed, which is tied to polar vortex strength during fall, winter, and spring months. This dependence manifests as both seasonal and sub-seasonal variability of MSTID amplitudes. Most existing SuperDARN MSTID studies have focused on observations from the Northern Hemisphere. This work uses an automated spectral approach previously used to study Northern Hemisphere winter daytime SuperDARN MSTIDs and applied it to all radars in both hemispheres for all times of day and all seasons for the years 2010-2021. This helped us identify the Southern Hemisphere radars with the highest quality data. One radar for which the retrievals worked particularly well was FIR which illustrates suppressed MSTID activity following the minor SSW beginning on 6 September 2019. This suggests that Southern Hemisphere MSTIDs, like their Northern Hemisphere counterparts, have GW sources in the lower/middle neutral atmosphere and are modulated by the polar vortex jet.\ 

}, author = {James Fox and Nicholas Guerra and Thomas Pisano and Michael Molzen and Nathaniel Frissell and Lynn Harvey and Joseph Klobusicky and Mark Fenner and Joseph Baker and Michael Ruohoniemi} } @proceedings {877, title = {Detection of SuperDARN-Observed Medium Scale Traveling Ionospheric Disturbances in the Southern Hemisphere}, year = {2024}, month = {03/2024}, publisher = {HamSCI}, address = {Cleveland, OH}, abstract = {

Traveling Ionospheric Disturbances are quasi-periodic variations in the plasma that exist in the upper atmosphere and they impact the propagation of radio waves. Medium Scale Traveling Ionospheric Disturbances (MSTIDs) are defined as TIDs which travel at 100-250 m/s and have periods within the 1 hour range. Previously, most of the existing research has focused on MSTIDs in the Northern Hemisphere. This project seeks to determine whether there is enough data available to recognize seasonal trends in MSTID occurrence in the Southern Hemisphere. Currently, we have found some success in applying the PyDarnMusic algorithm to identify periods of high and low MSTID activity in the southern hemisphere in SuperDARN and have had success in replicating an existing study on the Falkland Islands radar. Going forward, we hope to refine the techniques which were originally used to identify MSTIDs in the Northern Hemisphere for use on the Southern Hemisphere in order to gain a better understanding of their climatology.

}, author = {James P. Fox and Joseph Klobusicky and Nathaniel A. Frissell} } @proceedings {749, title = {Lunar Dust Particle Simulation in the (12-6) Lennard-Jones Potential Approximation}, year = {2023}, month = {03/2023}, publisher = {HamSCI}, address = {Scranton, PA}, abstract = {

We model lunar dust particles as interacting ellipsoidal dipoles by means of Lennard-Jones potentials (L-J). Lunar surface dust particles are continuously bombarded by plasma charge particles coming from the solar wind. It has been recognized that solar wind bombardment leads to strong intergrain interactions between dust particulates leading to collective effects such as attraction of charged dust particles. Formation of electrostatically ordered dust structures is believed to be due to strong attractive van der Waals-like potentials at distances in the order of interparticle separation. Dust-dust electrostatic interactions and collisions may lead to particle coalescence or dust-lumps kept together due to Coulomb forces. On the other hand, dust ionization occurs after solar wind electrons collide with grains in the plasma sheath formed on the lunar surface. Particle coalescence and to an extent condensation is feasible when an attractive potential is present. Ellipsoidal dipole condensation is possible in the presence of a Lennard-Jones (L-J) potential.

}, author = {Rachel Marie Frissell and Joseph Klobusicky and Argyrios Varonides and Amir Zamanian} }