@proceedings {875, title = {Wave Activity in Thermospheric Vertical Winds and Temperatures at Subauroral Latitudes}, year = {2024}, month = {03/2024}, publisher = {HamSCI}, address = {Cleveland, OH}, abstract = {

The need for high precision measurements of vertical winds with uncertainties less than 3-5 m/s and a temporal cadence of 1-2 min has made it exceedingly difficult to study the response of the thermosphere to gravity wave activity.\  Herein we present subauroral, midlatitude thermospheric wave measurements of 630 nm OI emission from a 15 cm narrow field Fabry Perot Interferometer, named the Hot Oxygen Doppler Imager (HODI).\  These measurements of temperature and vertical wind velocities are from a first light campaign at Jenny Jump Observatory (40.9 N, 74.9 W) located in northwestern New Jersey. The heightened sensitivity of HODI enables analysis of gravity wave behavior with uncertainties of 3-5 m/s for vertical wind speeds and 10-15 K for temperatures for two-minute exposures. Data was collected during periods of geomagnetically quiet and active conditions, and apparent wave structures were seen during both conditions.\  One detailed observation, taken the night of July 25, 2022, enabled the ~90-deg phase shift between vertical winds and temperatures to be inferred, as per standard gravity wave polarization relations with viscous dissipation.\  However, most other observations found to have little correlation between the temperature and vertical winds, which we speculate may be a result of the propagation and interaction of multiple wave events. Traveling ionospheric disturbances (TIDs) are often described as the ionospheric signature of the passage of gravity waves, and we provide comparisons of select wave events to medium scale TIDs using differential total electron count (TEC) maps.

}, author = {Anneliese Schmidt and John W. Meriwether and Matthew B. Cooper and Andrew J. Gerrard and Lindsay V. Goodwin and Shun-Rong Zhang and Gilbert Jeffer and Chris Callie} } @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} } @conference {399, title = {Novel methods for characterizing ionospheric irregularities in the high-latitude ionosphere (ePoster)}, booktitle = {HamSCI Workshop 2020}, year = {2020}, month = {03/2020}, publisher = {HamSCI}, organization = {HamSCI}, address = {Scranton, PA}, abstract = {

Plasma structuring in the high-latitude ionosphere impacts over-the-horizon radio communication and global navigation systems, and is an important space weather effect. Therefore, characterizing the formation and evolution of these structures is critically important. It is useful to create {\textquoteleft}{\textquoteleft}irregularity spectra", which quantify the sizes of plasma structures in the high-latitude ionosphere.\ \ The shape of the spectra (and other characteristics) can provide insight into the source of the irregularities. From this information it is then possible to forecast the occurrence of irregularities and predict their impact on radio wave propagation and communications. We are able to compute irregularity spectra by leveraging the phased array design of several incoherent scatter radars (ISRs), and using some unique properties of the F-region plasma at high-latitudes.\ \ In this presentation we will describe how we develop and apply a novel technique for ISR measurements to resolve high-latitude ionospheric irregularity spectra at a finer resolution than has been previously possible with ground-based instruments. We will motivate the newly developed ISR technique, describe its methodology, and provide some first results demonstrating its effectiveness. This technique will enable future studies that will directly link high-latitude ionospheric plasma structure drivers to their impact on radio wave communications.

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