Using radar observations and reanalysis data for 9 years, we demonstrate clearly for the first time that resonant interactions between tides and annual and semiannual oscillations do occur in the mesosphere and lower thermosphere. The resonant matching conditions of frequency and wavenumber are exactly satisfied for the interacting triad. At some altitudes, the secondary waves are stronger than the tides, thus in tidal studies, the secondary waves may be mistaken for the tides if no carefully.

Our lidar observations reveal the complete microphysical process of hydrometeors falling from mid-level stratiform clouds. We find that the surface rainfall begins as supercooled mixed-phase hydrometeors fall out of a liquid parent cloud base. We find also that the collision–coalescence growth of precipitating raindrops and subsequent spontaneous breakup always occur around 0.6 km altitude during surface rainfalls. Our findings provide new insights into stratiform precipitation formation.

The planetary boundary layer (PBL) is the lowest part of the troposphere, and boundary layer height (BLH) is the depth of the PBL and is of critical importance to the dispersion of air pollution. The study presents the first near-global BLH climatology by using high-resolution (5-10 m) radiosonde measurements. The variations in BLH exhibit large spatial and temporal dependence, with a peak at 17:00 local solar time. The most promising reanalysis product is ERA-5 in terms of modeling BLH.

El Niño has an important influence on climate systems. There are obviously negative water vapor anomalies from radiosonde observations in the tropical western Pacific during El Niño. The tropical Hadley, Walker, and monsoon circulation variations are revealed to play different roles in the observed water vapor anomaly in different types of El Niños. The Walker (monsoon) circulation anomaly made a major contribution in the 2015/16 (2009/10) strong eastern Pacific (central Pacific) El Niño event.

The POLIPHON method can retrieve the height profiles of dust-related particle mass and ice-nucleating particle (INP) concentrations. Applying a dust case data set screening scheme based on the lidar-derived depolarization ratio (rather than Ångström exponent for 440–870 nm and AOD at 532 nm), the mixed-dust-related conversion factors are retrieved from sun photometer observations over Wuhan, China. This method may potentially be extended to regions influenced by mixed dust.

Using high-resolution lidar measurements, this process-based study reveals that the clear-day convective boundary layer evolves in four distinct stages differing in depth growth rate and depth fluctuation magnitudes. The accompanying entrainment zone thickness (EZT) shows a discrepancy in statistical mean and standard deviation for different seasons and developing stages. Common EZT characteristics also exist. These findings help us understand the atmospheric boundary layer evolution.

Using the Beijing MST radar echo-power observations collected during the period November 2011–May 2017, the structure and variability of the tropopause over Xianghe, China (39.75° N, 116.96° E), was presented. Our comparison results showed a good agreement between the radar and thermal tropopauses during all seasons. In contrast, the consistency between the radar and dynamical tropopauses is poor during summer. Diurnal oscillation in tropopause height is commonly observed during all seasons.

Turbulence dissipation rate has inter-annual variations and follows a lognormal distribution. The magnitudes of turbulence detected by radiosonde and radar are roughly comparable. Turbulence cannot predicted by instabilities well but trends to be vigorous under the instability condition. The propagating gravity waves in the lower atmosphere can enhance atmospheric instabilities, and the temporal variations of waves can roughly estimate the turbulence dissipation rate at different height.

Downward stratospheric intrusions are well known as an important source of tropospheric ozone. In the light of the present understanding, several unanswered questions remain regarding the use of VHF radars to identify stratospheric intrusions. Our study found that the radar-observed strong downdrafts preceding the rapid tropopause ascent are a strong diagnostic for possible intrusions. This will have important implications for air-quality monitoring and long-term estimation of troposphere ozone.

We present the first statistical results of vertical wind fluctuation spectra, which revealed a very shallow spectral structure, with mean slopes of −0.58 and −0.23 in the troposphere and lower stratosphere, respectively. No existing spectral theories can comprehensively explain the observed three-dimensional wind spectra, indicating that the spectral features of atmospheric fluctuations are far from fully understood.

The 6.5-day traveling planetary wave is able to impact the ionosphere/thermosphere via a dissipation mechanism. Ionospheric TEC and thermosphere O/N2 exhibit an apparent decrease as the result of extra meridional circulation induced by 6.5-day wave dissipation. Our work suggests that the modulation of E-dynamo is not the unique pathway through which planetary waves substantially influence the IT system.

The diurnal tide and its variability in the lower atmosphere over Chongyang (114.14ºE，29.53ºN) were studied based on the newly established Wuhan University VHF radar observations in the whole year of 2012. We find that the diurnal tide was the dominant tidal component and showed remarkable height and season variations, as well as dramatic short-term variability.