The effects of the 13–14 March 1989 great magnetic storm on the East Asian ionosphere have been re‐investigated using ground‐based and satellite measurements as well as theoretical simulation. Within introduction of new data like the Chinese ionosondes and DMSP F8 and F9 and low‐equatorial magnetometer data, we are able to track the ionospheric response at both the bottomside and topside ionosphere from middle to low latitude to obtain an overall understanding of storm‐time ionospheric change. Through the comparative study of different longitude bands, we found that the East‐Asian ionosphere was characterized by a strong westward electron density gradient persisting over a day at both the bottomside and topside ionosphere at mid‐low latitudes during the main and recovery phases of the storm. This feature was not studied in the previous literature for this event at this area. We then examine the effect through a numerical simulation work from the Thermosphere Ionosphere Electrodynamics General Circulation Model under Apex and Dipole geomagnetic fields. It is seen that the model well reproduces the zonal gradients during this event under realistic geomagnetic field model. The conditions favor for this structure requires a hemispheric asymmetry response of storm thermosphere as well as background condition and also the storm development which requires further investigation. This study shows that even very close stations would manifest totally different storm behaviors during the superstorm event suggesting a great challenge in the space weather prediction.

For the first time, we develop a local time and day of year dependent climatological model in different geomagnetic activity based on 630.0 nm Fabry‐Perot Interferometer (FPI) measurements over Kelan (38.7°N, 111.6°E) during 2011–2019. With this model, we analyze the regional climatological characteristics of nighttime thermospheric neutral winds, and a comparison is made with two recent versions of the Horizontal Wind Model series (HWMs), HWM07 and HWM14. Due to the location of Kelan far from the northern magnetic pole longitude at middle latitude, the statistical characterizations of meridional and zonal winds show some unique local time, seasonal, solar cycle and geomagnetic activity dependence. There are predominantly annual variations of horizontal winds characterized by rapid transitions from eastward December winds to westward or less eastward June winds and largest equatorward meridional winds during summer months. To some degree, the wind patterns show casual solar activity dependence especially for the zonal component. The maximum southward winds show negative relationship with increasing solar activity in summer months, while the maximum eastward winds present negative trend in winter months. The Kp dependencies are characterized by larger westward perturbation winds for all night and enhanced northward winds in the premidnight sector and equatorward surges in the postmidnight sector during strongly active conditions. With increasing solar flux, the westward perturbation winds become weaker at nights. Results also reveal that HWM14 predictions are in better agreement with Kelan FPI winds in the shape and magnitude than HWM07, and the consistency improves with increasing Kp.

As the first advanced modular phase array incoherent scatter radar (ISR) established in the Eastern Hemisphere at low latitudes, Sanya ISR (SYISR) can measure the line-of-sight (LOS) velocity of ion drift in multiple directions, potentially yielding the spatial distribution of ionospheric plasma drift. Three beam-scanning modes are designed for plasma drift detection: meridian, zonal and cross-shaped (both meridian and zonal) plane, which will provide the distribution of plasma drift in latitude/longitude as well as altitude. The altitude profile of plasma drift and the first presented distribution of low latitude plasma drift in the meridian plane for March to May 2021 are inversed through LOS velocity using cross-shaped and meridian beam-scanning modes, respectively. A statistical correlation coefficient between the ${\mathrm{v}}_{\mathrm{p}\mathrm{n}}$ and crest-to-trough ratio (CTR) of equatorial ionization anomaly (EIA) TEC and a case study of magnetic storm response in plasma drift show that the inversed plasma drift can be a good indicator in response to the changes in atmospheric tide and solar wind at different time scales and explain the corresponding ionospheric electron density variations at low and equatorial latitudes. This study proves that the SYISR-measured plasma drift is reliable and will play an important role in the atmosphere-ionosphere-magnetospheric coupling study in the East Asian region.