A low-frequency inertial atmospheric gravity wave (AGW) event was studied with lidar (40.5° N, 116° E), meteor radar (40.3° N, 116.2° E), and TIMED/SABER at Beijing on 30 May 2012. Lidar measurements showed that the atmospheric temperature structure was persistently perturbed by AGWs propagating upward from the stratosphere into the mesosphere (35–86 km). The dominant contribution was from the waves with vertical wavelengths ${\mathsf{\lambda }}_{\mathrm{z}}=8-10\mathrm{km}$ and wave periods ${\mathrm{T}}_{\mathrm{ob}}=6.6\pm 0.7\mathrm{h}$ . Simultaneous observations from a meteor radar illustrated that MLT horizontal winds were perturbed by waves propagating upward with an azimuth angle of $\mathsf{\theta }=247°$ , and the vertical wavelength ( ${\mathsf{\lambda }}_{\mathrm{z}}=10\mathrm{km}$ ) and intrinsic period ( ${\mathrm{T}}_{\mathrm{in}}=7.4\mathrm{h}$ ) of the dominant waves were inferred with the hodograph method. TIMED/SABER measurements illustrated that the vertical temperature profiles were also perturbed by waves with dominant vertical wavelength ${\mathsf{\lambda }}_{\mathrm{z}}=6-9\mathrm{km}$ . Observations from three different instruments were compared, and it was found that signatures in the temperature perturbations and horizontal winds were induced by identical AGWs. According to these coordinated observation results, the horizontal wavelength and intrinsic phase speed were inferred to be ~560 km and ~21 m/s, respectively. Analyses of the Brunt-Väisälä frequency and potential energy illustrated that this persistent wave propagation had good static stability.

In March 2020, an all-solid-state dual-wavelength narrow-band lidar system was deployed. A total of 226 nights spanning from March 2020 to July 2022 were employed in order to investigate the seasonal variations of calcium atoms and ions in the mesosphere over Beijing (40.41°N, 116.01°E). The Ca⁺ layer shows general annual variation, while a semiannual variation is observed on the Ca layer. The calcium atomic column densities ranged from 2.0 × 10⁶ to 1.1 × 10⁸ cm⁻², and the calcium ion column densities ranged from 1.6 × 10⁶ to 4.2 × 10⁸ cm⁻². The mean centroid heights of Ca⁺ and Ca are 98.6 km and 93.0 km, respectively, and the centroid heights of Ca⁺ and Ca are mostly influenced by annual variations. The seasonal variation in the Ca⁺ and Ca layers in Beijing exhibits similarities to that of Kühlungsborn (54°N). While the peak density of Ca⁺ in Beijing are similar to those observed in Kühlungsborn, the peak density of the Ca layer in Beijing is about half of that reported in the Ca layer at 54°N. We provide an explanation for the disparities in the column abundance and centroid altitude of the Ca layer between Yanqing and Kühlungsborn, discussing variations in neutralization among different metal ions.

Based on long-term lidar (light detection and ranging) observations at Yanqing (40.5°N, 116°E) and Pingquan (41°N, 118.7°E), cloud events occurred in the vicinity of the stratopause above Beijing were reported for the first time. These events occurred with tenuous and sparse layers within the altitude range of 33–65 km, and the maximum VBSC value ranged from $1\times {10}^{-10}{\mathrm{m}}^{-1}{\mathrm{sr}}^{-1}$ to $5.5\times {10}^{-9}{\mathrm{m}}^{-1}{\mathrm{sr}}^{-1}$. Considering temperature and water vapor measurements from SABER/TIMED, the occurrence mechanism of these lidar-observed cloud events was examined. It was found that some cloud layers resulted from the nucleation of water vapor due to the local meteorological changes in the middle atmosphere, while other lidar-observed clouds could comprise floating clusters of cosmic dust, hydrate droplets, volcanic ash, space traffic exhaust, etc. These cloud events are rare cloud-like phenomena in the middle atmosphere observed by lidars at midlatitudes in China; they differ from NLCs and PSCs in terms of altitude distribution and seasonal variation, and the relevant microphysics processes behind their occurrence are likely meaningful to meteorology at midlatitudes.

The prediction accuracy of the General Circulation Model (GCM) is influenced by the effectiveness of gravity wave activity parameterization. Although research focuses on small-scale horizontal gravity wave activity as a carrier for energy and momentum coupling between atmospheric layers, routine observations of horizontal gravity wave activity on scales less than a dozen kilometers are scarce due to limitations in observational instruments. This paper presents a method for observing small-scale horizontal gravity waves using monostatic Rayleigh lidar, along with the associated data processing workflow. The data processing results indicate that the observed gravity waves generally exhibit wavelengths less than 3 km and phase velocities less than 0.5 m/s. Furthermore, the annual variation in small-scale horizontal gravity waves displays a semi-annual oscillation (SAO), like that observed in medium- and large-scale waves. This suggests that the observed gravity waves originate from secondary gravity waves resulting from saturation dissipation or breaking.

The characteristics and formation mechanisms of lightning activity during the lifetime of Super Typhoon Doksuri (2023) were investigated using ERA5 reanalysis data and observation data from the World-Wide Lightning Location Network (WWLLN) and Himawari-8/9 satellite. The lightning activity exhibited pronounced intermittent outbreak behavior, and intense lightning flashes mainly occurred in the outer rainband region approximately 200–600 km from the typhoon center. The occurrence of intense lightning was mainly related to the development of deep convections which were characterized by a high CAPE index and low cloud-top brightness temperature. In the landfall stage, intense lightning outbreaks may have been further modulated by the orographic lifting from the underlying surface and island thermal effects. Strong updrafts within the typhoon provided favorable conditions for intracloud microphysical electrification processes. The formation of intense lightning was interpreted via the non-inductive charging mechanism and validated using E-WRF model simulations. During the first rapid-intensification episode, intense inner-core lightning preceded the typhoon intensity peak by 14–41 h; during the re-intensification episode, it occurred ~9 h after the typhoon peak. These insights into the intense lightning activity in Super Typhoon Doksuri (2023) contribute to improving typhoon forecasting and disaster warning in the Western Pacific.