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1. Multi-instrument observations of polar cap patches and traveling ionospheric disturbances generated by solar wind Alfvén waves coupling to the dayside magnetosphere

   https://doi.org/10.5194/angeo-40-619-2022  

   Prikryl, Paul ; Gillies, Robert G. ; Themens, David R. ; Weygand, James M. ; Thomas, Evan G. ; Chakraborty, Shibaji ( January 2022 , Annales Geophysicae)

   Abstract. During minor to moderate geomagnetic storms, caused by corotatinginteraction regions (CIRs) at the leading edge of high-speed streams (HSSs), solar windAlfvén waves modulated the magnetic reconnection at the daysidemagnetopause. The Resolute Bay Incoherent Scatter Radars (RISR-C andRISR-N), measuring plasma parameters in the cusp and polar cap, observedionospheric signatures of flux transfer events (FTEs) that resulted in theformation of polar cap patches. The patches were observed as they moved over the RISR, and the Canadian High-Arctic Ionospheric Network (CHAIN)ionosondes and GPS receivers. The coupling process modulated the ionospheric convection and the intensity of ionospheric currents, including the auroral electrojets. The horizontal equivalent ionospheric currents (EICs) are estimated from ground-based magnetometer data using an inversion technique. Pulses of ionospheric currents that are a source of Joule heating in the lower thermosphere launched atmospheric gravity waves, causing travelingionospheric disturbances (TIDs) that propagated equatorward. The TIDs wereobserved in the SuperDual Auroral Radar Network (SuperDARN) high-frequency (HF) radar groundscatter and the detrended total electron content (TEC) measured by globallydistributed Global Navigation Satellite System (GNSS) receivers. 

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2. First Observations of Large Scale Traveling Ionospheric Disturbances Using Automated Amateur Radio Receiving Networks

   https://doi.org/10.1029/2022GL097879  

   Frissell, Nathaniel A. ; Kaeppler, Stephen R. ; Sanchez, Diego F. ; Perry, Gareth W. ; Engelke, William D. ; Erickson, Philip J. ; Coster, Anthea J. ; Ruohoniemi, J. Michael ; Baker, Joseph B. H. ; West, Mary Lou ( March 2022 , Geophysical Research Letters)

   We demonstrate a novel method for observing Large Scale Traveling Ionospheric Disturbances (LSTIDs) using high frequency (HF) amateur radio reporting networks, including the Reverse Beacon Network (RBN), Weak Signal Propagation Reporter Network (WSPRNet), and PSKReporter. LSTIDs are quasi‐periodic variations in ionospheric densities with horizontal wavelengths >1,000 km and periods between 30 and 180 min. On Nov 3, 2017, LSTID signatures were observed simultaneously over the continental United States in amateur radio, SuperDARN HF radar, and GNSS Total Electron Content with a period of ∼2.5 hr, propagation azimuth of ∼163°, horizontal wavelength of ∼1680 km, and phase speed of ∼1,200 km hr⁻¹. SuperMAG SME index enhancements and Poker Flat Incoherent Scatter Radar measurements suggest the LSTIDs were driven by auroral electrojet intensifications and Joule heating. This novel measurement technique has applications in future scientific studies and for assessing the impact of LSTIDs on HF communications.

    

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3. First Conjugate Observations of Medium‐Scale Traveling Ionospheric Disturbances (MSTIDs) in the Europe‐Africa Longitude Sector

   https://doi.org/10.1029/2018JA026018  

   Martinis, Carlos ; Baumgardner, Jeffrey ; Mendillo, Michael ; Wroten, Joei ; MacDonald, Timothy ; Kosch, Michael ; Lazzarin, Monica ; Umbriaco, Gabriele ( March 2019 , Journal of Geophysical Research: Space Physics)

   All‐sky imagers located in Asiago, Italy (45.87^oN, 11.53^oE; 40.7^omagnetic latitude) and Sutherland, South Africa (32.37^oS, 20.81^oE; −40.7^omagnetic latitude) are used to study magnetically conjugate medium scale traveling ionospheric disturbances (MSTIDs). We present initial results from the first year of joint Asiago‐Sutherland data sets from July 2016 to June 2017. The 630.0‐nm airglow perturbations showing different kinds of waves were frequently observed. Some of these wave events resemble MSTIDs propagating south‐westward in Asiago, typical direction observed at other longitude sectors in the northern hemisphere. They are mostly observed as single bands propagating through the field of view of the all‐sky imagers. We select and analyze five cases of magnetically conjugate bands associated with MSTIDs. The bands observed at Sutherland move mainly westward, noticeably different from the north‐west direction of propagation of MSTIDs observed in the southern hemisphere. We compare the MSTIDs propagation speeds and find that three cases show larger values at Sutherland. When we compare the zonal speeds all the cases show larger values at Sutherland. On average, the propagation speed at Sutherland is 20% larger and the zonal speed is ~35% larger. The westward motion at Sutherland is explained by taking onto account how its magnetic declination (~24^oW) affects the orientation of the bands. The larger speed at Sutherland is due to the weaker Earth's magnetic field in the southern hemisphere and the particular configuration of the magnetic field lines in this longitude sector.

    

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4. Detection and Three‐Dimensional Reconstruction of Concentric Traveling Ionosphere Disturbances Induced by Hurricane Matthew on 7 October 2016

   https://doi.org/10.1029/2022ja030690  

   Chen, Yutian ; Yue, Dongjie ; Zhai, Changzhi ; Zhang, Shun‐Rong ( December 2022 , Journal of Geophysical Research: Space Physics)
5. Experimenting With Frequency‐And‐Angular Sounding to Characterize Traveling Ionospheric Disturbances Using the LWA‐SV Radio Telescope and A DPS4D

   https://doi.org/10.1029/2018RS006690  

   Obenberger, K. S. ; Dao, E. ; Dowell, J.D. ( February 2019 , Radio Science)