A severe winter haze event was observed with a Raman–Mie lidar, providing high-resolution profiles of the atmospheric vertical structure. By integrating collocated radiosonde and surface meteorological data, the key meteorological characteristics, influencing factors, and interaction mechanisms governing the formation and evolution of this haze event were analyzed. The solar radiation plays a significant role in haze development, with a strong coupling between aerosols and temperature.

This study proposes an inversion method for atmospheric-aerosol or cloud microphysical parameters based on dual-wavelength lidar data. It is suitable for the inversion of uniformly mixed and single-property aerosol layers or small cloud droplets. For aerosol particles, the inversion range that this algorithm can achieve is 0.3–1.7 μm. For cloud droplets, it is 1.0–10 μm. This algorithm can quickly obtain the microphysical parameters of atmospheric particles and has better robustness.

We observed the seeder–feeder process among double-layer clouds using a cloud radar and microwave radiometer. By defining the parameters of the seeding depth and seeding time of the upper cloud affecting the lower cloud, we find that the cloud particle terminal velocity is significantly enhanced during the seeder–feeder period, and the lower the height and thinner the thickness of the height difference between double-layer clouds, the lower the height and thicker the thickness of seeding depth.

We put forward a new algorithm for joint observation of the cloud boundary by lidar and Ka-band millimetre-wave cloud radar. Cloud cover and boundary distribution characteristics are analysed from December 2020 to November 2021 in Xi'an. More than 34 % of clouds appear as a single layer every month. The maximum and minimum normalized cloud cover occurs in summer and winter, respectively. The study can provide more information on aerosol–cloud interactions and forecasting numerical models.

According to the absorption spectrum characteristics of oxygen A-band, a comprehensive budget is made in connection with various errors. The main purpose is to select a group of detection wavelengths with excellent performance and small error to match the evaluated radar system model, so as to provide a reference idea for the actual establishment of the experimental system in the future.