Understanding the thermodynamic horizontal structure of the mesopause is essential for studying atmospheric wave dynamics and energy transport. However, conventional models like MSISE-00 exhibit some discrepancies from lidar observations in the mesopause. To obtain a more reliable horizontal temperature structure, this study integrates coordinated lidar observations from Urumqi, Yuzhong, and Yangbajing with models using a three-dimensional variational (3DVAR) data assimilation method to construct a high-resolution temperature field over northwestern China. The assimilated temperature profiles closely match lidar observations, with the RMSE (root mean square error) of residual reductions of 67.35% at Urumqi, 60.69% at Yuzhong, and 34.80% at Yangbajing. Independent validation at Korla showed a RMSE of residual reductions of 40.14%, confirming the model’s effectiveness. The thermodynamical horizontal structures of the mesopause obtained from this model were also analyzed. The lidar-based model for the mesopause extends the observation results from disparate lidar stations to the area between lidar stations and will contribute to a deeper understanding of upper atmospheric dynamics.

The 589 nm three-frequency lidar systems are widely employed for detecting atmospheric parameters in the mesosphere and lower thermosphere (MLT). Recently, the single-peak atomic frequency discriminator (SPAFD) has enabled 589 nm three-frequency lidars to measure wind fields in the stratosphere and mesosphere. However, research on their application for near-surface aerosol measurements remains limited. This paper proposes a method for diurnal aerosol detection using the 589 nm three-frequency lidar integrated with SPAFD. The specific configuration of the lidar system is described in detail, along with the retrieval algorithm for aerosol optical parameters derived from the three-frequency backscatter signals. Continuous 69-h observation results of the aerosol backscatter ratio are provided, followed by an analysis of the diurnal evolution of the planetary boundary layer (PBL) height. This approach enables existing 589 nm lidar systems to acquire aerosol diurnal detection capabilities without additional hardware costs or operational expenses. At present, the retrieval of aerosol extinction coefficients is constrained to altitudes above 10 km due to geometric overlap factor limitations. To overcome this, a dedicated low-altitude detection channel will be integrated in future iterations to enable full-altitude measurements. This advancement will establish the 589 nm lidar as a highly efficient tool for full-altitude, diurnal atmospheric detection.

We present an analysis of thermal and dynamical structures in the mesopause and lower thermosphere (MLT) region (82–106 km) using ∼1,870 hr of sodium (Na) lidar observations at Yuzhong (36.0°N, 104.2°E) from March 2023 to May 2025. Mesopause altitudes exhibit strong seasonal dependence, ranging from 88 km in summer to 102 km in winter, with dual temperature minima observed in spring (89/101 km) and autumn (85/100 km). Minimal vertical temperature variation occurs in spring (∼5 K at 85–100 km), contrasting with larger gradients in autumn/winter. Temperature biases between lidar and TIMED/SABER satellite data show altitude‐dependent thresholds (∼92 km summer, ∼97 km autumn/winter), revealing satellite negative biases (3–5 K) below and positive biases (12–20 K) above these levels. Comparisons with the Starfire Optical Range station (35°N, 106.5°W) highlight 1–10 K springtime temperature differences linked to localized inversion layers. Zonal winds reverse from eastward to westward at ∼102 km (spring/summer) and ∼100 km (autumn/winter), while meridional winds display pronounced seasonal heterogeneity, including enhanced northward flows in spring (90–96 km) and winter (>91 km) inconsistent with horizontal wind model (HWM14) and the NCAR Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM‐X). The discrepancies between lidar observations and model predictions highlight the need for improved gravity wave parameterization and regional‐scale wind characterization. These results advocate for multi‐instrument networks (lidar, meteor radar, Fabry‐Perot interferometers) under the Chinese Meridian Project to constrain regional atmospheric models and improve understanding of MLT dynamical processes.