Abstract In this study, multiple data sets from Beidou geostationary orbit satellites total electron contents (TECs), ionosonde, meteor radar, magnetometer, and model simulations have been used to investigate the ionospheric responses in Asian‐Australian sector during September 2017 geomagnetic storm. It was found that long‐duration daytime TEC enhancements lasted 7 12 were observed by satellite constellation. This is a unique event as prominent persisted storm recovery phase when activity...

Abstract The effects of volcanic eruptions on the ionosphere have been well studied, however, evidence for anticipated upper atmospheric neutral variations and their exact extents change are rarely available. Here, we report dramatic thermospheric disturbances following 15 January 2022 Tonga eruption. GRACE‐FO Swarm‐C observations from accelerometers exhibited three successive density waves at ∼500 km altitudes propagating concentrically across globe 200–450 m/s phase speed two converged...

Ionospheric electron density profiles retrieved from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites measurements 6 November 2006 to 5 February 2007 are used study ionospheric nighttime enhancements under winter, solar minimum, geomagnetically quiet conditions. In this work, peak densities of F 2 layer ( N m ) derived COSMIC found be in reasonably good agreement with ionosonde observations during night. Therefore morphology is investigated at...

In this paper, observations from CHAMP and GRACE during 2002–2010 are used to study the seasonal variations of thermospheric density by characterizing dominant modes variability as empirical orthogonal functions (EOFs). Our results showed that first three EOFs captured most variability, which can be large 98% total variability. Subsequently, obtained mean field, corresponding amplitudes applied construct a model at 400 km under geomagnetically quiet conditions. Thermospheric shows strong...

Abstract The ionospheric radio occultation measurements from Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites during 2007–2012 are utilized to analyze variations of the hemispheric asymmetry in equatorial ionization anomaly (EIA) solstice seasons. A index ( h ) is introduced quantitatively characterize relative interhemispheric or north‐south differences EIA crests. seasonal, solar activity, longitudinal dependences investigated these low moderately...

Abstract In this study, the mechanisms of interhemispheric asymmetry equatorial ionization anomaly (EIA) in June solstice at solar minimum were investigated through a series simulations using Thermosphere Ionosphere Electrodynamics General Circulation Model. Our results indicate that transequatorial neutral wind is main cause asymmetry. The transports plasma from summer hemisphere to winter hemisphere, leading an enhancement EIA crest. Meanwhile, ion production and loss are also important...

Abstract In this study, coordinated airglow imager, GPS total electron content (TEC), and Beidou geostationary orbit (GEO) TEC observations for the first time are used to investigate characteristics of nighttime medium‐scale traveling ionospheric disturbances (MSTIDs) over central China. The results indicated that features MSTIDs from three types generally consistent, whereas MSTID GEO in better agreement with those images as compared TEC, given significantly affected by Doppler effect due...

Abstract The total electron content (TEC) data measured by the Jason, CHAMP, GRACE, and SAC‐C satellites, in situ densities from CHAMP vertical E × B drifts ROCSAT, have been utilized to examine ionospheric response October 2003 superstorms. combination of observations multiple satellites provides a unique global view storm effects, especially over Pacific Ocean American regions, which were under sunlit conditions during main phases results this study are as follows: (1) There substantial...

Abstract Ionospheric observations from the ground‐based GPS receiver network, CHAMP and GRACE satellites ionosondes were used to examine topside bottomside ionospheric variations at low middle latitudes over Pacific American sectors during October 2003 superstorms. The latitudinal variation storm time response of total electron content (TEC) generally consistent with those up‐looking TEC. TECs heights below satellite altitudes main phases comparable to, or even less than, quiet values....

Abstract In this study, the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) electron densities (Ne) from 200 to 800 km during 2006–2017 are used investigate middle‐latitudinal band structure of nighttime ionosphere. The main results as follows. (1) nighttime, Ne at about ±40° geomagnetic latitudes is generally greater, especially in topside (2) Double bands relatively high seen all longitudes equinoxes, while only one latitudinal clearly visible specific...

Abstract The strongest geomagnetic storm in the preceding two decades occurred May 2024. Over these years, ground‐based observational capabilities have been significantly enhanced to monitor ionospheric weather. Notably, newly established Sanya incoherent scatter radar (SYISR) (Yue, Wan, Ning, & Jin, 2022, https://doi.org/10.1038/s41550‐022‐01684‐1 ), one of critical infrastructures Chinese “Meridian Project,” provides multiple parameter measurements upper atmosphere at low latitudes...

Abstract Nonlinear cyclotron resonance is known to cause the scattering of ring current protons deviate from predictions quasi‐linear theory, when wave‐induced motion dominates over adiabatic motion. This study employed a test‐particle simulation investigate nonlinear processes and their dependence on amplitude, frequency, wave normal angle ψ electromagnetic ion (EMIC) waves. As equatorial pitch α eq increases, proton becomes dominated by wave's force responds nonlinearly. When become...

Abstract The extraordinary eruption of the Tonga volcano on 15 January 2022 lofted material to heights exceeding 50 km, marking highest observed since satellite era. This caused significant disturbances spanning from hydrosphere up thermosphere. Our recent investigation discovered dramatic thermospheric responses at altitudes. study, however, provides physical insights into two main possible processes, secondary gravity waves (GWs) and Lamb waves, which may explain those large‐scale...

We report the first model result for ion production rates and densities of positive ions, negative electrons in dayside Martian ionosphere from 0 to 220 km. These calculations are made at solar zenith angle 77° low activity periods. The calculated electron density is compared with radio occultation measurements by Mars Global Surveyor (MGS) 4/5 on Constellation Observing System Meteorology, Ionosphere Climate (COSMIC) Earth. Our calculation suggests that daytime can be divided into D , E F...

Abstract The modulation of the ultrafast Kelvin wave (UFKW) on equatorial ionosphere is investigated, using satellite neutral wind and temperature observations in mesosphere/lower thermosphere (MLT) ground‐based global maps total electron content (TEC) observations. UFKW signatures are identified least squares fitting spectra for MLT zonal wind, temperature, TEC, Constellation Observing System Meteorology, Ionosphere, Climate (COSMIC) density profiles, providing strong evidence neutral‐ion...

Abstract In this study, the in situ electron density measurements from Challenging Minisatellite Payload (CHAMP) and solar extreme ultraviolet (EUV) radiation Solar Extreme Ultraviolet Experiment instrument on board Thermosphere Ionosphere Mesosphere Energetic Dynamics satellite, both with a time resolution of 1.5 hr, are used to explore peak response ionospheric F 2 region plasma 27‐day EUV flux variation. The delays changes obtained CHAMP satellite vary 0 about 3 days. Meanwhile,...

Abstract The uplooking total electron contents (TECs) from the GRACE, SWARM‐A, TerraSAR‐X, and MetOp‐A satellites in situ density (Ne) SWARM‐A were utilized to investigate topside ionospheric conditions during 7–8 September 2017 geomagnetic storm. rate of TEC index (ROTI) (RODI), which are derivative indices Ne, respectively, also used characterize irregularities. main results this study as follows: (1) There significant enhancements seen first phase (2) did not show unusual enhancement at...

Abstract The low‐latitude ionospheric TEC observed by the Beidou geostationary satellite showed large enhancement during 27–30 August 2018 of storm recovery phase. cause positive phase has yet to be resolved. In this study, multiple observations, including aurora, high‐latitude convection, potential, and maps, were used study contributions from high‐speed solar wind ionosphere storm. It was found that effective in modulating intensity size auroral oval, potential pattern. Thermosphere...

Abstract Detached subauroral proton arcs are commonly observed during the recovery phase of geomagnetic storms, and have been extensively investigated. However, there is limited study on their occurrence main storms. This investigated nightside detached auroras (NDAs) by far‐ultraviolet imager onboard Defense Meteorological Satellite Program spacecraft. The NDAs occurred in sector, separated from equatorward boundary auroral oval, were phases storm 02 October 2013. appears to correlate with...

The equivalent winds at the F layer peak are derived from global ionosonde data to investigate their solar activity variations. With increasing activity, found of nonlinearly decreased diurnal amplitudes in all seasons most stations. This implies that increase ion drag more than compensates for pressure gradients and thus restrains amplitude high activity. phase generally shifts later higher It is first time explicitly report this striking feature emerged so many Another pronounced has a...

The auroral hemispheric power (HP) has been calculated from the averaged energy flux derived Far‐ultraviolet emission observations made by global ultraviolet imager (GUVI) instrument on board Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite during 2002–2007. This HP was used to study how variations in seasonal asymmetries changed with changing geomagnetic activity. Our results showed that there were persistent differences quiet conditions. There of about 1–3 GW...

Several mechanisms including heat transport due to zonal winds, chemical heating and field‐aligned ion drag have been proposed explain the formation of Equatorial Thermosphere Anomaly (ETA), but cause ETA crests in thermosphere temperature is still a mystery. Our companion study (Lei et al . , 2012) has revealed that mainly contributes trough, little effect on crests. In this study, associated with winds recombination are examined assess their contributions production basis National Center...

Meridional winds at the magnetic meridian in upper thermosphere are derived from peak height and density of ionospheric F 2 layer as retrieved by Constellation Observing System for Meteorology, Ionosphere, Climate (COSMIC) satellites 4 months November 2006 to February 2007. These (referred COSMIC winds) first validated comparison multiple locations with obtained ground‐based incoherent scatter radar (ISR) Fabry‐Perot interferometer (FPI) measurements. Then longitudinal variations these...

In this paper the impact of field‐aligned ion drag on equatorial thermosphere temperature and density is quantitatively investigated basis National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model (NCAR TIEGCM) simulations under high solar activity (F107 = 180). The increase upward vertical winds over magnetic equator associated with additional divergence meridional winds, caused by inclusion drag, leads to a reduction in at through enhanced...

Abstract In this study, the ionospheric observations from ionosondes, ground‐based GPS receivers, Gravity Recovery and Climate Experiment (GRACE) MetOp‐A satellites, Fabry‐Perot interferometer over Asian‐Australian sector have been used to investigate responses of F 2 peak topside ionosphere October 2013 geomagnetic storm, particularly during recovery phase. The comparison between multiple simultaneous revealed a contrasting behavior in East Asia upward looking total electron content...