Abstract In this work, we identified 65 auroral arcs that stretched out from the equatorward boundary of oval with azimuthal extensions, and investigated their upstream triggering, by utilizing conjunctions between THEMIS probes all‐sky imagers at AGO P1 South Pole stations. The results show magnetopause motions induced pressure enhancements associated IMF discontinuities or foreshock cavities likely generate upward FACs in closed field lines near magnetopause. inward caused...

Abstract High‐intensity long‐duration continuous auroral electrojet (AE) activity (HILDCAA) events are associated with intensification of relativistic electron fluxes in the inner magnetosphere. The physical mechanisms this not well established yet. We study observations by Time History Events and Macroscale Interactions during Substorms (THEMIS) spacecraft near earth plasma sheet at radial distances 10 Earth radii, transition region between tail dipole‐like magnetic configurations, referred...

Abstract We report the first simultaneous, common‐volume lidar observations of thermosphere‐ionosphere Fe (TIFe) and Na (TINa) layers in Antarctica. also observational discovery nearly one‐to‐one correspondence between TIFe aurora activity, enhanced ionization layers, converging electric fields. Distinctive have a peak density ~384 cm −3 mixing ratio peaks around 123 km, ~5 times mesospheric layer maximum. All evidence shows that + ion‐neutralization is major formation mechanism layers. The...

Abstract Dipolarizing flux bundles (DFBs) have been suggested to transport energy and momentum from regions of reconnection in the magnetotail high latitude ionosphere, where they can generate localized ionospheric currents that produce large nighttime geomagnetic disturbances (GMDs). In this study we identified DFBs observed midnight sector ∼7 ∼10 R E by THEMIS A, D, during days 2015–2017 whose northern hemisphere magnetic footpoints mapped near Hudson Bay, Canada, compared them isolated...

Abstract. We present the development considerations and design for ground-based instrumentation that is being deployed on East Antarctic Plateau along a 40° magnetic meridian chain to investigate interhemispheric magnetically conjugate geomagnetic coupling other space-weather-related phenomena. The stations are west coast of Greenland. autonomous adaptive low-power instrument platforms in designed operate unattended remote locations at least 5 years. They utilize solar power AGM storage...

Abstract We present the first clear observational connection between interplanetary shock impact angles and magnetospheric ultralow frequency (ULF) wave activity. perform a comparative study of two solar wind shocks with relatively similar strengths, but one being nearly frontal and, other, highly inclined. utilize multipoint observations magnetometers based in space on ground for comparisons. For satellites stations occupying local time positions, we find that ULF waves have larger...

Abstract Ionospheric irregularities can adversely affect the performance of Global Navigation Satellite System (GNSS). However, this opens possibility using GNSS as an effective ionospheric remote sensing tool. Despite monitoring has been undertaken for decades, these in multiple spatial and temporal scales are still not fully understood. This paper reviews Virginia Tech’s recent studies on multi-scale ground-based space-based observations. First, relevant background their impact signals is...

Abstract A circuit analogy for magnetosphere‐ionosphere current systems has two extremes drivers of ionospheric currents: electric fields/voltages constant while current/conductivity vary—the “voltage generator”—and field/conductivity “current generator.” Statistical studies ground magnetometer observations associated with dayside Transient High Latitude Current Systems (THLCS) driven by similar mechanisms find contradictory results using this paradigm: some associate THLCS voltage...

Abstract The magnetosphere‐ionosphere system response to extreme solar wind driving conditions depends on both the and ionospheric conductivity. Since are rare, there few opportunities control for one parameter or another. 17 March 2013 2015 geomagnetic storms driven by coronal mass ejections (CME) provide such opportunity. two events occur during same illumination conditions; in particular, near equinox day of year leading similar conductivity profiles. Moreover, CMEs arrive at time...

Abstract Traveling convection vortices (TCVs) are generally produced by field‐aligned currents (FACs) at high latitudes associated with transient changes of the magnetopause. This paper presents multipoint conjugate observations events magnetopause measured in space and on ground. The showing radial fluctuation association sudden increases solar wind dynamic pressure were detected both Time History Events Macroscale Interactions during Substorms Geostationary Operational Environmental...

Abstract We report the first lidar observations of regular occurrence mid‐latitude thermosphere‐ionosphere Na (TINa) layers over Boulder (40.13°N, 105.24°W), Colorado. Detection tenuous (∼0.1–1 cm −3 from 150 to 130 km) was enabled by high‐sensitivity Doppler lidar. TINa occur regularly in various months and years, descending ∼125 km after dusk ∼150 before dawn. The downward‐progression phase speeds are ∼3 m/s above 120 ∼1 below 115 km, consistent with semidiurnal tidal speeds. One or more...

Abstract The CRI based Kriging method has been proposed for reconstruction of the ionospheric f o F 2 in China region. In this regional‐dependent variable is adopted as relative difference between estimated and modeled values . Introducing distance regional can be realized by using method. would improve accuracy stability compared with straight reconstruction. Based on systematic measurements Chinese ionosounde network computer simulations have done different solar activity years, months...

Abstract Interplanetary (IP) shocks drive magnetosphere‐ionosphere (MI) current systems that in turn are associated with ground magnetic perturbations. Recent work has shown IP shock impact angle plays a significant role controlling the subsequent geomagnetic activity and perturbations; for example, highly inclined asymmetric MI responses due to interhemispherical magnetospheric compressions, while almost head‐on more symmetric responses. However, there few observations confirming such...

Abstract Long‐lasting Pc5 ultralow frequency (ULF) waves spanning the dayside and extending from L ∼ 5.5 into polar cap region were observed by conjugate ground magnetometers. Observations MMS satellites in magnetosphere magnetometers on confirmed that ULF closed field lines due to fundamental toroidal standing Alfvén waves. Monochromatic at lower latitudes tended maximize their power away noon both morning afternoon sectors, while more broadband higher have a wave maximum near noon. The...

The impact of interplanetary shocks on the magnetosphere can trigger magnetic substorms that intensify auroral electrojet currents. These currents enhance ground field perturbations (d$B$/d$t$), which in turn generate geomagnetically induced (GICs) be detrimental to power transmission infrastructure. We perform a comparative study d$B$/d$t$ variations response two similarly strong shocks, but with one being nearly frontal, and other, highly inclined. Multi-instrument analyses by Time History...

Abstract A variety of statistical studies have shown that the ionospheric polar potential produced by solar wind‐magnetosphere‐ionosphere coupling is linear for weak to moderate wind driving but becomes nonlinear during periods very strong driving. It has been this applies two‐cell convection develops southward interplanetary magnetic field (IMF) and also reverse cells develop northward IMF. This described as saturation, it appears begin when electric greater than 3 mV/m. Utilizing...

Abstract We report on simultaneous observations of electromagnetic ion cyclotron (EMIC) waves associated with traveling convection vortex (TCV) events caused by transient solar wind dynamic pressure ( P d ) impulse events. The Time History Events and Macroscale Interactions during Substorms (THEMIS) spacecraft located near the magnetopause observed radial fluctuations magnetopause, GOES measured sudden compressions magnetosphere in response to increases . During events, EMIC were...

The phenomenon of ultra-low frequency geomagnetic pulsations was first observed in the ground-based measurements 1859 Carrington Event and has been studied for over 100 years. Pulsation is considered to be “ultra” low when it lower than natural frequencies plasma, such as ion gyrofrequency. Ultra-low are a source noise some geophysical analysis techniques, aeromagnetic surveys transient electromagnetics, so critical develop near real-time space weather products monitor these pulsations....

An autonomous adaptive low-power instrument platform (AAL-PIP) chain of six stations has been newly established on East Antarctic Plateau along the 40° geomagnetic meridian, to investigate interhemispheric geomagnetically conjugate current systems, waves, and other space weather phenomena in Polar Regions. These stations, PG0 PG5, which host magnetometers (Fluxgate Searchcoil), dual frequency GPS receivers, HF radio experiment, run autonomously with solar power two-way satellite...

Abstract. Ground-based observations can be used to provide substantial support for Cluster/Double Star measurements and greatly enhance the mission's scientific return. There are six Chinese ground stations involved in coordinated cluster/Double ground-based instrument observations. Among them, Zhongshan Station Antarctica Yellow River on Svalbard closely magnetic conjugate situated under ionospheric projection of magnetospheric cusp regions, which, combined with satellite data, a perfect...

Abstract Throat auroras frequently observed near local noon have been confirmed to correspond magnetopause indentations, but the generation mechanisms for these indentations and detailed properties of throat aurora are both not fully understood. Using all‐sky camera magnetometer observations, we reported some new observational features as follows. (1) can occur under stable solar wind conditions cause clear geomagnetic responses. (2) These responses be simultaneously at conjugate meridian...