Version 5 (v05) of the thermospheric wind data from the Michelson Interferometer for Global High‐resolution Thermospheric Imaging (MIGHTI) instrument on the Ionospheric Connection Explorer (ICON) mission has been recently released, which largely avoids local‐time dependent artificial baseline drifts that are found in previous versions of the ICON/MIGHTI wind data. This paper describes monthly climatologies of zonal‐mean winds and tides based on the v05 ICON/MIGHTI data under geomagnetically quiet conditions (Hp30 < 3o) during April 2020–March 2022. Green‐line winds in the lower thermosphere (90–110 km) and red‐line winds in the middle thermosphere (200–300 km) are analyzed, as these data cover both daytime and nighttime. The latitude and height structures of zonal‐mean winds and tides are presented for each month, and the results are compared with the widely used empirical model, Horizontal Wind Model 2014 (HWM14). The ICON/MIGHTI and HWM14 results are in general agreement, providing a validation of the v05 ICON/MIGHTI data. The agreement is especially good for the zonal‐mean winds. Amplitudes of lower thermospheric tides from ICON/MIGHTI tend to be larger than those from HWM14 as well as from an empirical model, Climatological Tidal Model of the Thermosphere (CTMT). This could be due to the influence of interannual variability of the tides. The amplitude structure of lower thermospheric tides in HWM14 does not match those from ICON/MIGHTI and CTMT in some months. Also, HWM14 underestimates the meridional‐wind amplitude of the migrating diurnal tide in the middle thermosphere. These results highlight the need for improved tidal representation in HWM14.

Tidal signatures in sporadic E (Es) layer have been confirmed by observations and simulations. However, the effect of gravity waves (GWs) on the Es layer formation process has not yet been fully understood. In this paper, the modulation of Es layers by GWs is examined through numerical simulations, in which a physics‐based model of Es layer is forced by neutral winds from the High Altitude Mechanistic General Circulation Model that can resolve GWs with horizontal wavelengths longer than 156 km (λ_h > 156 km). Comparison of the simulation results with and without the GWs (1,350 km > λ_h > 156 km) forcing reveals that the inclusion of GWs leads to short‐period (1.2–3 hr) density perturbations in Es layers, which are also seen in ground‐based ionosonde observations. At a given time, the metallic ion density at altitudes between 120 and 150 km can either increase (by up to ∼+600%) or reduce (by up to −90%) in response to GW forcing. The relative density perturbations are smaller (by up to 60%) between 90 and 120 km altitude. It is also found that the GW effect on the metallic ion density relates to the longitude, which is mostly explained by the geographical distribution of GWs activity in the mesosphere and lower thermosphere region. The longitudinal variation of the background geomagnetic field plays only a secondary role.

Sporadic E (Es) layer plays a prominent role in revealing both upward and downward atmosphere‐ionosphere coupling process. This study investigates the responses of Es layers to the May 2024 super geomagnetic storm by using 37 ground‐based ionosondes distributed globally and space‐based COSMIC‐2 radio occultation observations. The results show that Es layers were significantly enhanced during the recovery phase of geomagnetic storm. In addition, the enhanced Es layers mainly occurred over Southeast Asia, Australia, the South Pacific and the East Pacific. The temporal evolution of foEs disturbances over the Asian‐Australian sector clearly shows the “wave propagation” characteristics from high to low latitudes, indicating that the enhancements of the Es layers are most likely caused by the disturbed neutral winds in the E region. This study presents observational evidence for the downward impacts of the geomagnetic storm on the E‐region ionosphere.

Sporadic E (Es) layers are thin layers of concentrated metallic ions in the mesosphere and lower thermosphere region. Their occurrence can cause the uneven distribution of plasma density and affects the performance of the Global Navigation Satellite System and high/very high frequency radio communications. Currently, the three‐dimensional (3‐D) Es layer structure and evolution process have not yet been fully understood. Using the Fe⁺ layer as a proxy for Es layer, in this study, we investigated the structural and dynamic characteristics of the large‐scale Es layers extending thousands of kilometers over East Asia by using a 3‐D Es layer numerical model driven by neutral winds from the Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension model. The simulation results show that the Es layer is a tilted blanket rather than a narrow flat band. In addition, the Es layers mainly occur in the 3‐D spatial position of the convergent vertical wind shear. The apparent horizontal velocity (∼300–400 m/s) of Es structure is mostly westward and northward, which is different from the ion drift velocity (∼100 m/s). This indicates that Es structure can develop rapidly over a large area simultaneously rather than only drifting from one location to the next. This study systematically analyzed the physics of the 3‐D Es layer, which can be helpful for understanding the Es horizontal structure and dynamics recorded by different instruments, such as satellites and global navigation satellite system receiver networks.