@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 {835, title = {Comparative Analysis of Medium Scale Travelling Ionospheric Disturbances: Grape PSWS vs. SuperDARN}, year = {2024}, month = {03/2024}, publisher = {HamSCI}, address = {Cleveland, OH}, abstract = {

Medium Scale Traveling Ionospheric Disturbances (MSTIDs) are periodic fluctuations in ionospheric electron density associated with atmospheric gravity waves. They are characterized by wavelengths of 50-500 kilometers and periods of 15-60 minutes. This study presents initial findings from a comparative analysis of MSTID observations sourced from two distinct systems: the Super Dual Auroral Radar Network (SuperDARN) and the Grape Personal Space Weather Station (PSWS). The Grape PSWS, developed by the Ham Radio Science Citizen Investigation (HamSCI), is a small ground-based remote sensing device aimed at monitoring space weather parameters, including MSTIDs. It achieves this by monitoring a 10 MHz transmission from WWV, a National Institute of Standards and Technology (NIST) time standard station located near Fort Collins, Colorado, USA. In contrast, SuperDARN comprises a global network of high-frequency radars that offer extensive coverage of ionospheric plasma motion. This comparative investigation focuses on aligning MSTID observations obtained from Grape PSWS data with SuperDARN radar data. By investigating datasets from both platforms, these findings serve as initial results for an ongoing investigation of MSTIDs, laying the groundwork for a comprehensive understanding of their dynamics and impacts on ionospheric variability and space weather.

}, author = {Veronica I. Romanek and Nathaniel A. Frissell and Bharat Kunduri and J. Michael Ruohoniemi and Joseph Baker and William Liles and John Gibbons and Kristina Collins and David Kazdan and Rachel Boedicker} }