The submarine volcanic eruption at Tonga on 15 January 2022 was a devastated geohazardous rated as VEI (Volcanic Explosivity Index) 5-6, which was the most powerful since the 1883 Krakatoa VEI 6 eruption. The release of enormous amounts of energy into the atmosphere triggered significant geophysical disturbances. In this presentation, we provide various upper atmospheric observations to demonstrate local, regional, and global ionospheric disturbances, including TID global propagation with the most intense, persistent, and consistent wave mode at 300-350 m/s phase speed , EIA deformation and x-cross pattern of EIA crest evolution, equatorial irregularities and bubbles, substantial plasma density depletion. Timing of these and many other observed ionospheric responses was consistent with the Lamb wave arrival, despite of other waves including acoustic and gravity waves as well as tsunami waves were also present in specific regions.  The eruption-excited atmospheric waves produced not only TID global propagation but also modulated the wind dynamos in both E and F regions, driving electrodynamic changes closely associated with EIA and EPBs phenomena at equatorial and low latitudes. These results suggested a new vertical coupling channel through which the intense atmospheric surface disturbance processes can produce far-reaching and long-lasting geospace impacts.

How to cite: Zhang, S.-R., Aa, E., Vierinen, J., Erickson, P., Goncharenko, L., Coster, A., Wang, W., and Qian, L.: Atmosphere-ionosphere coupling following the Tonga eruption: global multi-scale ionospheric effects, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2886, https://doi.org/10.5194/egusphere-egu23-2886, 2023.

The massive explosive eruption of the Hunga Tonga volcano on 15 January generated atmospheric waves that were comparable with those generated by the Krakatoa 1883 eruption. The waves were recorded around the globe and affected also the ionosphere. We focus on observation of atmospheric waves in the troposphere and ionosphere in Europe. The tropospheric waves are studied using a large aperture array of microbarometers and the ionospheric disturbances are detected using continuous Doppler sounding. It is shown that long-period infrasound (periods longer than ~50 s) is observed simultaneously in the troposphere and ionosphere about an hour after the arrival of the first pressure pulse (Lamb wave) in the troposphere. Data analysis confirms propagation approximately along the shorter great circle path both for the infrasound and the Lamb wave. It is suggested that the infrasound propagated into the ionosphere probably due to imperfect refraction in the lower thermosphere. The observation of infrasound in the ionosphere at such large distances from the source (over 16 000 km) is rare and differs from ionospheric infrasound detected at large distances from the epicenters of strong earthquakes, because in the latter case the infrasound is generated locally by seismic waves. An unusually large traveling ionospheric disturbance (TID) observed in Europe and associated with the pressure wave from the Hunga Tonga eruption is also discussed. In addition, a probable observation of wave in the mesopause region approximately 25 min after the arrival of pressure pulse in the troposphere using a 23.4 kHz signal from a transmitter 557 km away is shown.

How to cite: Chum, J., Šindelárová, T., Koucká Knížová, P., Podolská, K., Rusz, J., Danielides, M., and Schmidt, C.: Atmospheric and ionospheric disturbances in Europe induced by Hunga eruption on 15 January 2022, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3289, https://doi.org/10.5194/egusphere-egu23-3289, 2023.

The explosive eruption of the Tonga underwater volcano (20.53°S, 175.38°W) occurred at ~04:15 UT on 15 January 2022. In this study, the networks of ground-based barometers, magnetometers, and global navigation satellite system (GNSS) receivers recorded disturbances that traveled away from the eruption with acoustic speeds in the atmosphere and ionosphere. The primary disturbances with periods of several hours in the magnetic fields and total electron content (TEC) observations reveal the electrodynamics changes in the upper atmosphere and the coupling of E- and F-region dynamo. The atmospheric Lamb wave propagating upward caused the secondary waves in the ionosphere and seeds irregularities following the leading front of the primary disturbances. The global radio occultation technique onboard the FORMOSAT‐7/COSMIC2 (F7/C2) mission sounds the ionosphere in the vertical direction, which shows the large-scale disturbances with scale > 200 km in the ionospheric F region and irregularities. On the other hand, the co-located instruments, including a seismometer, atmospheric electric field meter, wind profile radar, magnetometer, and GNSS receiver, monitored perturbations in the lithosphere, atmosphere, and ionosphere simultaneously at a certain location (29°N, 103°E) that is ~ten thousands of kilometers northwest away from the eruption. The primary phenomena of the eruption-associated disturbances are the long-period changes (period of ~ 2 hr) in the ionospheric TEC and the magnetic field in the upper atmosphere (above 100 km altitude), indicating the interactions of the ionospheric electrodynamics. The secondary phenomena included wind disturbances in the troposphere, which contribute to short-period changes (up to ten minutes) in air pressure, ground vibrations, and atmospheric electric field. The near-surface disturbances propagating upward further triggered short-period variations in the geomagnetic field and TEC. The primary changes in ionospheric electrodynamics, wind disturbance in the lower atmosphere, its upward propagation, and the resonance reveal the complex coupling phenomena due to the eruption and enrich our understanding of the geosphere coupling.

How to cite: Sun, Y.-Y., Chen, C.-H., Zhang, X., Gao, Y., and Liu, J.-Y.: Tonga eruption-induced disturbances in lithosphere, atmosphere, and ionosphere and their coupling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16536, https://doi.org/10.5194/egusphere-egu23-16536, 2023.

The Atmospheric Waves Experiment (AWE) is a new NASA mission aimed at investigating the effects of tropospheric weather on space weather. An Advanced Mesospheric Temperature Mapper (AMTM) airglow imager will be deployed on the International Space Station (ISS) in December 2023. This proven instrument will map the nighttime mesospheric temperature at the altitude of the hydroxyl (OH) layer (~87 km) during two years, providing 2D gravity wave (GW) fields over a 600 km field-of-view, every second.

Four state-of-the-art models will also help achieving the three science objectives:

• Quantify the seasonal and regional variabilities and influences of GWs near the mesopause,
• Identify the dominant dynamical processes controlling GWs observed near the mesopause,
• Estimate the wider role of GWs in the Ionosphere-Thermosphere-Mesosphere (ITM).

This presentation will give an overview of the AWE mission and describe the future data levels using synthetic images.

How to cite: Pautet, P.-D., Taylor, M. J., Zhao, Y., Forbes, J., Fritts, D., Eckermann, S., Liu, H.-L., Snively, J., Janches, D., Lamborn, B., Latvakovski, H., and Syrstad, E.: The Atmospheric Waves Experiment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10168, https://doi.org/10.5194/egusphere-egu23-10168, 2023.

This investigation is focused on resolving daily diurnal eastward propagating tide with zonal number 3 (DE3) (3,3) Hough mode variations and their potential impact on the ionosphere, using TIMED/TIDI and SABER, ICON/MIGHTI, COSMIC-2 Global Ionospheric Specification (GIS), and TIME-GCM. A Hough mode fitting approach was used to estimate (3,3) amplitudes and phases from observations, while Fourier decomposition was utilized for TIME-GCM and COSMIC-2/GIS to validate and probe potential ionospheric impacts. In 2020-2021, TIDI, SABER, and MIGHTI (3,3) daily tidal estimates were in good agreement, with correlation coefficients ranging from 0.73-0.83. In 2010, mean daily (3,3) amplitude variability in TIDI and SABER reached ~5 m/s and ~2 K, respectively, but could increase by a factor of 2 or more over a week. Furthermore, strong increases in DE3 from days to weeks correspond with similar increases in F-region ionospheric wave-4 amplitudes from both models and observations which signify the lower atmospheric meteorology impact on the ionosphere.

How to cite: Dhadly, M., Jones, M., and Drob, D.: Short-term Variability of the Non-migrating Tide DE3 (from SABER, TIDI, and MIGHTI) and its Impact on the Ionosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8368, https://doi.org/10.5194/egusphere-egu23-8368, 2023.

High-rate radio occultation (RO) in COSMIC2 (FORMOSAT7) enables us to investigate the continuous variability of the ionosphere at a Spatio-temporal resolution which was unthinkable a few decades ago. We present unique characteristics of ionospheric wavenumber structures observed using COSMIC2 RO data, not reported before. Altitude-longitude maps of normalized electron density of local time ionosphere in the Equatorial Ionization Anomaly (EIA) region, indicate wavenumber structures with vertically tilted phase fronts. The longitudinal extent of a tilted wavenumber 4 (WN4) phase front approximates its zonal wavelength in the local-time ionosphere, i.e., ~90⁰ in longitudes. WN4 filtered component indicates a more significant tilt (when visible), with a larger longitudinal extent of a wavenumber structure in the vertical plane. High latitudinal resolution investigation of wavenumber structure presents a significant difference in the characteristics of wavenumber structures at different geomagnetic latitudes within the EIA region. During the daytime WN4 structure in the EIA crest region is out of phase with respect to that in the EIA trough region. However, the two were observed to be in phase with each other during the nighttime. These characteristics also vary with altitude. Above 400 km WN4 structure in the EIA crest and trough region is seen to be in phase with each other at all local times. CREST. These results highlight that, while the direct role of non-migrating tides, which provides the vertical tilt to the wavenumber structure, maybe the dominant mechanism, however, electrodynamical transport of plasma in the EIA region driven by eastward zonal electric field during the daytime also plays a significant role in the formation of wavenumber structure. During the nighttime, in the absence of the fountain effect, wavenumber structures are driven by the direct forcing of non-migrating tides within the EIA region. The results will be presented and discussed in light of existing knowledge of the formation of wavenumber structures and the impact of non-migrating tides on the local-time ionosphere.

How to cite: Joshi, L. M.: Characteristics of ionospheric wavenumber structures in COSMIC-2 RO observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8943, https://doi.org/10.5194/egusphere-egu23-8943, 2023.

During geomagnetic storms, ionospheric plasma is transported across high latitudes by the enhanced solar wind – magnetosphere coupling. The anti-sunward plasma convection results in polar cap plasma anomalies, such as the tongue of ionisation (TOI). Fast plasma uplifts at sub-auroral latitudes, due to the vertical coupling via electric fields and/or thermospheric neutral winds, are generally responsible for these long-lasting TOI anomalies. Particularly in the North American sector, TOI anomalies, as well as associated electric drifts, have been detected in observations using global positioning system signals (total electron content), in-situ satellite measurements, and altitude-resolved profiles from ground-based incoherent scatter radars. Recent modelling developments have enabled simulations of the TOI anomalies, even under extreme geomagnetic storm conditions. In this study, rare direct observations of plasma uplifts by the Millstone Hill incoherent scatter radar (288.5°E, 42.6°N) during the geomagnetic storm of November 2004 are analysed and compared to first-principles numerical simulations. These indicate that enhanced convection electric fields are the primary source of plasma uplifts, at least during the storm's main phase, and that the choice of plasma convection model is crucial for accurate modelling results.

How to cite: Pokhotelov, D., Günzkofer, F., Goncharenko, L., and Erickson, P. J.: Observations and modelling of fast vertical sub-auroral plasma uplift during geomagnetic storms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8276, https://doi.org/10.5194/egusphere-egu23-8276, 2023.

In this paper, the data measured with Digisonde at the low-latitude Hainan station from 2003 to 2016 are statistically analyzed to specify the diurnal average variations of the bottom-side F region ionospheric plasma velocity vector V. This is the first comprehensive analysis of Digisonde measurements of low latitude F region plasma velocities in the East Asian sector that use a database covering more than one solar cycle. The vector components V_N, V_E, and V_Z are analyzed for two levels of solar flux and two levels of geomagnetic activity, respectively. The diurnal variations of the average V_Z show three positive peaks near the prereversal enhancement (PRE) period, pre-midnight, and before sunrise, respectively, and a prominent valley in the early morning. The averaged V_Z significantly increased with solar flux in the period of PRE during equinoxes, but it was only slightly affected by Kp. The V_E component was westward in daytime and eastward in nighttime. The average eastward V_E increased significantly with solar flux but decreased with Kp, whereas the average westward V_E exhibited only a small variation with solar flux and Kp. The average V_N was almost southward independent of solar flux and Kp. The plasma velocities over the Hainan station were mainly caused by the electric field and neutral wind. Our results show that the features of the vertical and meridional velocities over the Hainan station in the morning associated with the formation of the equatorial ionization anomaly (EIA).

How to cite: Wang, G., Shi, J., Wang, Z., Cheng, Z., Wang, X., and Shang, S.: Statistical study on plasma velocities in bottom-side ionosphere over low latitude Hainan station: Digisonde measurement, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10426, https://doi.org/10.5194/egusphere-egu23-10426, 2023.

Atmospheric Gravity Waves (AGWs) forced in the lower atmosphere are known to have a significant impact on the mesosphere and lower thermosphere (MLT) region. In the ionosphere, they can generate Medium-Scale Traveling Ionospheric Disturbances (MSTIDs). These disturbances roughly occur on time scales of 15−80 min and are therefore often parametrized rather than directly resolved in ionosphere models. The energy and momentum transport by AGW-TIDs strongly depends on their wave parameters. Measurements of AGW-TIDs in the MLT region and determination of the wave parameters (vertical and horizontal wavelength, wave period and propagation direction) are therefore an essential step to improve ionosphere modelling. However, measurements that provide a good resolution in the vertical dimension (≲ 10 km) and time (≲ 10 min) as well as a large enough coverage in the horizontal dimension (≳ 300 × 300 km) are difficult at MLT altitudes. We show, that combined measurements of the EISCAT VHF incoherent scatter radar and the Nordic Meteor Radar Cluster allow to determine the wave parameters of AGW-TIDs across the whole MLT region. Fourier filter methods are used to separate wave modes by wavelength, period and propagation direction. The extracted wave modes are fitted with wave functions in time-altitude and horizontal cross sections which gives the wave parameters. The coverage regions of the two applied instruments are separated only by approximately 10 km in altitude, which allows to identify a single wave mode in both measurements. We present the developed techniques on the example of a strongly pronounced AGW-TID measured on July 7, 2020. As a first application, two measurement campaigns have been conducted in early September and mid-October 2022 to study possible changes in AGW-TID parameters due to the MLT fall transition occurring around equinox. Another possible application of our method is to infer thermospheric neutral winds from the observed waves. We demonstrate this process under the assumption of the anelastic dissipative gravity wave dispersion relation.

How to cite: Günzkofer, F., Pokhotelov, D., Stober, G., Mann, I., Vadas, S. L., Becker, E., Tjulin, A., Gulbrandsen, N., Kero, J., Kozlovsky, A., Lester, M., Mitchell, N., Nozawa, S., Tsutsumi, M., and Borries, C.: Combined measurements with the EISCAT radar and the Nordic Meteor Radar Cluster to determine AGW-TID wave parameters, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9189, https://doi.org/10.5194/egusphere-egu23-9189, 2023.

Ionospheric perturbations during the Sudden Stratosphere Warming (SSW) events reflect the lower atmosphere-ionosphere coupling and thus become a research hot-spot. Nevertheless, most previous related studies focused on the low latitude. Comparatively, ionospheric perturbations in the middle and high latitudes during the Arctic SSW events are relatively less studied. The current work analyzed the ionosphere perturbations in the American southern middle latitude during the Arctic SSW with total electron content and NmF2. Unexpected strong connection between the major Arctic SSW and the ionospheric variations in the American southern middle latitude were detected. Upper thermosphere circulation anomaly and the enhanced semi-diurnal lunitidal influence during the SSW may be crucial to such connection.

How to cite: Liu, J. and Zhang, D.: Ionospheric perturbations in the American southern middle latitude during the Sudden Stratosphere Warming events, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12121, https://doi.org/10.5194/egusphere-egu23-12121, 2023.

The impact of the stratospheric Quasi-Biennial Oscillations (QBO) and Semi-Annual Oscillations (SAO) and physics of gravity waves (GW) on the dynamics and transport in the Mesosphere and Lower Thermosphere (MLT) has been examined in simulations of two Whole Atmosphere Models (WAM and WACCM-X) during the last decade. In the low-latitude MLT the year-to-year variations of the diurnal tide amplitudes and mean flow of whole atmosphere simulations constrained below 40 km by reanalysis data are in the good agreement with the observed interannual variability. The Mar-Apr diurnal tide amplitudes simulated by models display the observed enhancements (~50-100%) of amplitudes during the westerly QBO years. The observed influence of QBO and SAO on the tidal dynamics in the MLT is well captured by simulations that are capable to reproduce the global and regional tidal variability deduced from the space-borne and ground-based measurements of temperature and winds. Comparisons between simulations and observations, along with the model sensitivity studies highlight needs to quantify and constrain impact of mesoscale GW dynamics and physics in whole atmosphere predictions.

How to cite: Yudin, V., Goncharenko, L., Karol, S., Lieberman, R., McInerney, J., Pedatella, N., and Yudin, V.: Interannual Variability of Tidal Dynamics in the Tropical MLT, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11009, https://doi.org/10.5194/egusphere-egu23-11009, 2023.

Sanya (18.3°N, 109.6°E) Incoherent Scatter Radar (SYISR) is a newly built ISR in low latitude China. The unique features of SYISR include a single-channel directly connected T/R unit and antenna, a radar array monitoring and calibration network, environmental adaptability design and open architecture. Since 2022, we have run SYISR almost continuously. In this presentation, at first we will generally describe the technical details of SYISR. Then we will show the ionospheric observations made by SYISR, including equatorial bubble, ion line and plasma line results, and derivation of low latitude neutral wind and ionospheric electric field. At the end, we will introduce the development status of the SYISR Tristatic System.

How to cite: Yue, X., Wan, W., Ning, B., Ding, F., Wang, J., Cai, Y., Zhang, N., Li, M., Wang, Y., Zhou, X., and Wang, Z.: Low Latitude Ionosphere Observed by the Sanya Incoherent Scatter Radar, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5770, https://doi.org/10.5194/egusphere-egu23-5770, 2023.

The upper boundary height of the traditional community general circulation model of the ionosphere‑thermosphere system is too low to be applied to the topside ionosphere/thermosphere study. In this study, the National Center for Atmospheric Research Thermosphere‑Ionosphere‑Electrodynamics General Circulation Model (NCAR‑TIEGCM) was successfully extended upward by four scale heights from 400–600 km to 700–1200 km depending on solar activity, named TIEGCM‑X. The topside ionosphere and thermosphere simulated by TIEGCM‑X agree well with the observations derived from a topside sounder and satellite drag data. In addition, the neutral density, temperature, and electron density simulated by TIEGCM‑X are morphologically consistent with the NCAR‑TIEGCM simulations before extension. The latitude‑altitude distribution of the equatorial ionization anomaly derived from TIEGCM‑X is more reasonable. During geomagnetic storm events, the thermospheric responses of TIEGCM‑X are similar to TIEGCM. However, the ionospheric storm effects in TIEGCM-X are stronger than those in TIEGCM and are even opposites at some middle and low latitudes due to the presence of more closed magnetic field lines. DMSP observations prove that the ionospheric storm effect of TIEGCM-X is more reasonable. The well‑validated TIEGCM‑X has significant potential applications in ionospheric/thermospheric studies, such as the responses to storms, low‑latitude dynamics, and data assimilation.

How to cite: Cai, Y., Yue, X., Wang, W., Zhang, S., Liu, H., Lin, D., Wu, H., Yue, J., Bruinsma, S. L., Ding, F., Ren, Z., and Liu, L.: Altitude extension of NCAR-TIEGCM (TIEGCM‑X) and evaluation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12894, https://doi.org/10.5194/egusphere-egu23-12894, 2023.

The Swarm satellite constellation provides an excellent opportunity to explore ionospheric current systems. In this study we performed a detailed analysis of the ionospheric radial current (IRC) and inter-hemispheric field-aligned current (IHFAC) estimates at equatorial and low latitudes derived from the single-satellite and dual-spacecraft (dual-SC) approaches. We found that the diurnal variations of average IHFACs from both approaches agree qualitatively with each other for all seasons. But the amplitudes of single-satellite results reach only about 70% of those from the dual-SC. This difference is attributed to the fact that only the magnetic field By component is utilized in the single-satellite approach, while both Bx and By components are considered in the dual-SC approach. Above the magnetic equator, the IRCs derived from single-satellite approach show spurious tidal signatures, caused by equatorial electrojet (EEJ) contributions to the dBy component. The EEJ does not contaminate dual-satellite results. Further, we improved the IHFACs from the dual-satellite approach by considering the local influence of the ambient magnetic field on current densities and normalize them to their ionospheric E-region footprints. Then we extend the analysis to ±60° MLat; the middle latitude IHFACs show features different from those at low latitudes. They are dominated by longitudinal wave-1 and wave-2 patterns. A superposition of these tidal components reflects confinement of the IHFAC modulation to daytime and the western hemisphere. The tidal signatures at middle latitudes are better organized in universal time than in local time. The strongest IHFACs appear at 18-19 UT, near noon in the American sector. This is related to the overlap with the South Atlantic Anomaly.

How to cite: Wang, F., Luehr, H., Xiong, C., Park, J., and Zhou, Y.: Improved field-aligned current and radial current estimates at low and middle latitudes deduced by the Swarm dual-spacecraft, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4278, https://doi.org/10.5194/egusphere-egu23-4278, 2023.

We present the migrating tidal winds decomposed jointly from multiple meteor radars in four longitudinal sectors situated in the equatorial mesosphere and lower thermosphere. The radars are located in Cariri, Brazil (7.4°S, 36.5°W), Kototabang, Indonesia (0.2°S, 100.3°E), Ascension Island, United Kingdom (7.9° S, 14.4°W), and Darwin, Australia (12.3°S, 130.8°E). Harmonic analysis was used to obtain amplitudes and phases for diurnal and semidiurnal solar migrating tides between 82 and 98 km altitude during the period 2005–2008. To verify the reliability of the tidal components calculated by the four meteor radar wind measurements, we also present a similar analysis for the Whole Atmosphere Community Climate Model winds, which suggests that the migrating tides are well observed by the four different radars. The tides include the important tidal components of diurnal westward-propagating zonal wavenumber 1 and semidiurnal westward-propagating zonal wavenumber 2. In addition, the results based on observations were compared with the Climatological Tidal Model of the Thermosphere (CTMT). In general, in terms of climatic features, our results for the major components of migrating tides are qualitatively consistent with the CTMT models derived from satellite data. In addition, the tidal amplitudes are unusually stronger in January–February 2006. This result is probably because tides were enhanced by the 2006 Northern Hemisphere stratospheric sudden warming event.

How to cite: Yi, W., Wang, J., Xue, X., Vincent, R., Batista, P., Tsuda, T., and Mitchell, N.: Coordinated Observations of Migrating Tides by Multiple Meteor Radars in the Equatorial Mesosphere and Lower Thermosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4606, https://doi.org/10.5194/egusphere-egu23-4606, 2023.

The seasonal and interannual variations of global tides of neutral winds in the mesosphere and lower thermosphere (MLT) are investigated based on the neutral horizontal wind data measured by TIMED Doppler interferometer (TIDI). The particular focus is on how the seasonal variation of tidal amplitude varies in response to solar cycle (SC) and to the quasi-biennial oscillation in winds in the lower stratosphere (SQBO). We find that the responses of seasonal variations of tides to SQBO and SC are comparable in magnitude to those of their corresponding annual means. Further, we show that the response patterns of seasonal variations of tides to SQBO and SC are not always similar to those of their corresponding annual means, which indicates that the tidal responses differ at different times of the year. In addition, we reveal that migrating tides show strong terannual oscillations (TAO) especially in meridional wind, whereas nonmigrating tides do not show obvious TAO.

How to cite: Liu, Y., Xu, J., Smith, A., and Liu, X.: Seasonal and Interannual Variations of Global Tides of Neutral Winds in the Mesosphere and Lower Thermosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10550, https://doi.org/10.5194/egusphere-egu23-10550, 2023.

In this study, the neutral wind observations from the Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument onboard Ionospheric CONnections (ICON) are used to investigate the longitudinal structure of zonal wind between 100 and 300 km during daytime. The four-peaked structure is prominent in June and August, and transforms to the three-peaked structure with altitude in October. The longitudinal wavenumber 1-4 patterns (WN1-WN4) are extracted, then the altitude-month distributions of WN1-WN4 and their contributions to the longitudinal structure are compared. The amplitudes of WN3 and WN4 show seasonal dependence, and the amplitude of WN4 exhibits obvious vertical propagation from the mesosphere and lower thermosphere (MLT) to the upper thermosphere in summer and autumn. WN1 is an important contributor to the longitudinal structure, WN4 is the primary contributor in the lower altitude ranges in summer and autumn at three latitudes. The contributions of WN3 (WN1) increase holistically with latitude in summer (spring, autumn, and winter). And the main wave sources of WN1-WN4 are matched further in different seasons in the 100-106 km and 210-300 km altitude regions. The main wave sources of WN1 and WN2 have complex variations with altitude, latitude, and season, while WN3 (WN4) is clearly influenced by DE2 (DE3 and SE2).

How to cite: Li, D., Gao, H., Xu, J., Zhu, Y., Xu, Q., Liu, Y., and Liu, H.: Longitudinal Structures of Zonal Wind in the Thermosphere by the ICON/MIGHTI and the Main Wave Sources, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10463, https://doi.org/10.5194/egusphere-egu23-10463, 2023.

The ionospheric sporadic E (Es) layer is a thin and dense metallic ion layer that occasionally appears at altitudes between 95 and 125 km. The layer-forming process is controlled by the vertical wind shear that is closely linked to the atmospheric tides forced by solar radiation. The diurnal, semidiurnal, terdiurnal and quarterdiurnal variations in the Es layer occurrence rate have been revealed by observations. However, how the gravity wave affects the Es layer has not been well revealed. Using the 1-D Es layer model driven by neutral winds from the HIAMCM model (High Altitude Mechanistic general Circulation Model), this work simulated the physical process of the Es layer evolution modulated by gravity waves. The results show the short-period metallic ion density disturbance (1.5-3h) caused by gravity waves. The sporadic E layer can be destroyed or enhanced by gravity waves.

How to cite: Qiu, L., Yamazaki, Y., Yu, T., Becker, E., Miyoshi, Y., Qi, Y., Siddiqui, T. A., Stolle, C., Feng, W., Wang, J., and Liang, Y.: Numerical simulations of metallic ion density perturbations in sporadic E layers caused by gravity waves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6372, https://doi.org/10.5194/egusphere-egu23-6372, 2023.