Haiyun Xia

To capture rapidly evolving three-dimensional atmospheric flows, a stereoscopic wind camera incorporating 20 × 5 time-division-multiplexing MIMO Doppler lidar is proposed and experimentally validated. Evolving from a planar wind camera, the system combines a 10 × 10 focal-point array in a single-aperture multichannel telecentric telescope and 20 integrated laser–receiver pairs. Each pair sequentially measures five channels, while parallel data acquisition and transmission enable 100-channel volumetric sampling within a 1 s cycle. The system achieves a 30° field of view and a maximum detection range of 2.5 km. Rapid volumetric sampling of line-of-sight velocities reveals wind-field evolution, providing a temporally consistent set of observations for three-dimensional variational wind vector retrieval. This architecture enables high-refresh-rate observations of transient flows, with promising applications in aviation safety, meteorology, and wind engineering.

Vertical exchange between the atmospheric boundary layer (ABL) and the free troposphere (FT) is a key pathway for aerosol transport and can substantially influence surface air quality. In this study, an intense ABL‐FT exchange event over Shanghai on 29 March 2024 was captured and analyzed using ground‐based Doppler wind LiDAR, microwave radiometer, particle‐size spectrometer measurements, and numerical diagnostics. Southwesterly warm‐moist advection and daytime surface heating promoted the growth of a warm and moist boundary layer, while drier and more stably stratified air persisted above the ABL top. Under this thermodynamic background, the boundary‐layer jet and associated dynamical disturbances favored vigorous ABL‐FT exchange. During this period, vigorous vertical motions developed, with vertical velocities ranging from −1.5 to 2.0 m and extending to nearly 3 km. The estimated ABL‐FT air‐mass exchange flux ranged from −0.97 to 1.46 kg , with vertical motion accounting for 58.5% of the total exchange. During the exchange event, ultrafine‐particle concentrations increased markedly at the surface, while particles smaller than 10 nm did not show a corresponding increase. These observations are more consistent with downward transport of particles likely present aloft, followed by growth within the boundary layer, than with a purely local surface‐formation mechanism. This study highlights a possible linkage among dust intrusion, particle processes aloft, and ABL‐FT mixing in shaping near‐surface aerosol number concentrations, and advances understanding of vertical aerosol transport in megacity environments.

Low-level jets (LLJs) play an important role in aerosol transport and boundary-layer processes. This study utilizes coherent Doppler wind lidar observations to investigate the relationship between LLJ evolution and vertical aerosol redistribution during two dust episodes over Hefei, East China. Results show that changes in LLJ core height are associated with distinct aerosol distribution patterns during the two dust events. In the April 2021 event, the northwesterly jet core exhibits a dynamic vertical migration, descending from 2.5 to 0.3 km before reascending to 1.0 km during the surface PM ₁₀ peak (410 µg m ⁻³ ). The descending jet is accompanied by enhanced vertical wind shear (>0.04 s ⁻¹ ) near the lower jet interface and increased spectral width, together with a downward shift in the enhanced backscatter region. These changes coincide with the rapid increase in surface PM ₁₀ concentration, suggesting that enhanced dynamical variability and mixing conditions may have contributed to the downward redistribution of dust. Conversely, the March 2022 event is characterized by a relatively stable LLJ core and persistent lower tropospheric stability, which is associated with the persistence of aerosols within an elevated layer. Persistent wind shear and enhanced spectral width below the LLJ core coincided with the enhanced backscatter region. The PM ₁₀ peak occurred at 16:00 LT (UTC+8 h) on 14 March 2022, approximately 8 h after the inferred onset of frontal influence, coinciding with weakening lower tropospheric stability and changes in the backscatter structure above the site. Wind hodographs show a clockwise rotation of wind vectors that is qualitatively consistent with a possible contribution from inertial oscillation during LLJ evolution. Overall, the observations suggest two contrasting aerosol redistribution processes associated with LLJ evolution: rapid downward redistribution during jet descent and delayed surface influence when aerosols remain elevated under stable conditions. The results provide an observational basis for refining boundary-layer parameterizations in numerical weather prediction and air quality models.

Atmospheric gravity waves can transport momentum and energy and couple different atmospheric layers. Their propagation and dissipation have been widely studied in the stratosphere and mesosphere, whereas their excitation and trapping within tropospheric double-jet ducts remain less well constrained. Here we combine coherent Doppler wind lidar (CDWL) observations at Minfeng, ERA5 reanalysis, and WRF simulations to investigate how a nocturnal double-jet structure over the southern Taklimakan Desert excites and modulates tropospheric gravity waves. Three events in September 2021 occurred under a similar configuration, with a lower-level easterly jet below 4 km, an upper-level westerly jet at 6–7 km, and a weak-wind layer between them. Oscillations of 10–20 min occurred within the weak-wind layer, with maximum amplitudes near the strong shear zone at the base of the westerly jet, suggesting a role for shear-related dynamical instability in wave generation. ERA5 buoyancy-frequency profiles show a stable layer near 4–6 km that favored thermal ducting, and Scorer-parameter diagnostics further indicate concurrent Doppler ducting. As the easterly jet intensified, the waveguide compressed and wave frequencies increased, consistent with a shift of trapped modes toward higher frequencies. WRF reproduced the first two cases reasonably well, yielding dominant horizontal wavelengths of 7–14 km and eastward phase speeds near 6 m s⁻¹, but showed substantial discrepancies in the third. These results indicate that nocturnal double-jet structures can act as an effective tropospheric waveguide by trapping gravity waves through thermal and Doppler ducting and shifting trapped modes toward higher frequencies as the duct evolves.

Atmospheric gravity waves can transport momentum and energy and couple different atmospheric layers. Their propagation and dissipation have been widely studied in the stratosphere and mesosphere, whereas their excitation and trapping within tropospheric double-jet ducts remain less well constrained. Here we combine coherent Doppler wind lidar (CDWL) observations at Minfeng, ERA5 reanalysis, and WRF simulations to investigate how a nocturnal double-jet structure over the southern Taklimakan Desert excites and modulates tropospheric gravity waves. Three events in September 2021 occurred under a similar configuration, with a lower-level easterly jet below 4 km, an upper-level westerly jet at 6–7 km, and a weak-wind layer between them. Oscillations of 10–20 min occurred within the weak-wind layer, with maximum amplitudes near the strong shear zone at the base of the westerly jet, suggesting a role for shear-related dynamical instability in wave generation. ERA5 buoyancy-frequency profiles show a stable layer near 4–6 km that favored thermal ducting, and Scorer-parameter diagnostics further indicate concurrent Doppler ducting. As the easterly jet intensified, the waveguide compressed and wave frequencies increased, consistent with a shift of trapped modes toward higher frequencies. WRF reproduced the first two cases reasonably well, yielding dominant horizontal wavelengths of 7–14 km and eastward phase speeds near 6 m s⁻¹, but showed substantial discrepancies in the third. These results indicate that nocturnal double-jet structures can act as an effective tropospheric waveguide by trapping gravity waves through thermal and Doppler ducting and shifting trapped modes toward higher frequencies as the duct evolves.

Industrial parks represent critical nodes in the global carbon cycle and thus require accurate monitoring and modelling to support effective carbon management. Although satellite observations, ground-based measurements, and numerical modelling frameworks have been widely utilized, these approaches inherently struggle to simultaneously achieve high temporal and spatial resolution. In this study, high-resolution Lidar is integrated with the Weather Research and Forecasting model coupled with greenhouse gas fluxes (WRF-GHG) modelling to comprehensively diagnose the CO₂ accumulation–dispersion dynamics and their driving mechanisms within the Luoyuan Bay industrial park. The comprehensive analysis reveals a distinctive diurnal pattern of CO₂, characterized by nighttime accumulation and daytime dispersion. Lidar observations indicate that stable atmospheric conditions and valley terrain synergistically cause CO₂ to accumulate in low-lying areas at night, with concentrations exceeding 700 ppm. During daytime, strengthened southeasterly sea breezes and intensified turbulence promote its dispersion to the northwest and vertical uplift, reducing concentrations to 500-550 ppm. A significantly negative correlation between CO₂ concentration and wind speed is also confirmed. While the WRF-GHG model reproduces the overall temporal variation, it systematically underestimates CO₂ levels (420–460 ppm). The discrepancy is attributed to the limited spatial resolution of the emission inventory and the model’s inherent constraints in capturing terrain–wind field interactions within the bay. This study highlights the unique capabilities of coherent differential absorption Lidar, elucidates the key limitations of current modelling approaches, and provides a robust scientific basis for refining carbon verification systems and enhancing the performance of regional carbon models.

Industrial parks represent critical nodes in the global carbon cycle and thus require accurate monitoring and modelling to support effective carbon management. Although satellite observations, ground-based measurements, and numerical modelling frameworks have been widely utilized, these approaches inherently struggle to simultaneously achieve high temporal and spatial resolution. In this study, high-resolution Lidar is integrated with the Weather Research and Forecasting model coupled with greenhouse gas fluxes (WRF-GHG) modelling to comprehensively diagnose the CO₂ accumulation–dispersion dynamics and their driving mechanisms within the Luoyuan Bay industrial park. The comprehensive analysis reveals a distinctive diurnal pattern of CO₂, characterized by nighttime accumulation and daytime dispersion. Lidar observations indicate that stable atmospheric conditions and valley terrain synergistically cause CO₂ to accumulate in low-lying areas at night, with concentrations exceeding 700 ppm. During daytime, strengthened southeasterly sea breezes and intensified turbulence promote its dispersion to the northwest and vertical uplift, reducing concentrations to 500-550 ppm. A significantly negative correlation between CO₂ concentration and wind speed is also confirmed. While the WRF-GHG model reproduces the overall temporal variation, it systematically underestimates CO₂ levels (420–460 ppm). The discrepancy is attributed to the limited spatial resolution of the emission inventory and the model’s inherent constraints in capturing terrain–wind field interactions within the bay. This study highlights the unique capabilities of coherent differential absorption Lidar, elucidates the key limitations of current modelling approaches, and provides a robust scientific basis for refining carbon verification systems and enhancing the performance of regional carbon models.

Atmospheric gravity waves can transport momentum and energy and couple different atmospheric layers. Their propagation and dissipation have been widely studied in the stratosphere and mesosphere, whereas their excitation and trapping within tropospheric double-jet ducts remain less well constrained. Here we combine coherent Doppler wind lidar (CDWL) observations at Minfeng, ERA5 reanalysis, and WRF simulations to investigate how a nocturnal double-jet structure over the southern Taklimakan Desert excites and modulates tropospheric gravity waves. Three events in September 2021 occurred under a similar configuration, with a lower-level easterly jet below 4 km, an upper-level westerly jet at 6–7 km, and a weak-wind layer between them. Oscillations of 10–20 min occurred within the weak-wind layer, with maximum amplitudes near the strong shear zone at the base of the westerly jet, suggesting a role for shear-related dynamical instability in wave generation. ERA5 buoyancy-frequency profiles show a stable layer near 4–6 km that favored thermal ducting, and Scorer-parameter diagnostics further indicate concurrent Doppler ducting. As the easterly jet intensified, the waveguide compressed and wave frequencies increased, consistent with a shift of trapped modes toward higher frequencies. WRF reproduced the first two cases reasonably well, yielding dominant horizontal wavelengths of 7–14 km and eastward phase speeds near 6 m s⁻¹, but showed substantial discrepancies in the third. These results indicate that nocturnal double-jet structures can act as an effective tropospheric waveguide by trapping gravity waves through thermal and Doppler ducting and shifting trapped modes toward higher frequencies as the duct evolves.

Low-level jets (LLJs) significantly influence aerosol vertical transport and the resulting surface air quality. This study utilizes coherent Doppler wind lidar observations to characterize the impact of LLJ dynamics on vertical aerosol redistribution during two typical dust episodes over Hefei, East China. Results show that the vertical trajectory of the LLJ core is associated with dust transport through the combined effects of mechanical shear and thermal stability. In the April 2021 event, the northwesterly jet core exhibits a dynamic vertical evolution, descending from 2.5 km to 0.3 km before reascending to 1.0 km by the time of the surface PM₁₀ peak (410 μg m^-3). This movement maintains enhanced wind shear (> 0.04 s^-1) and associated mechanical turbulence at the jet's lower interface. Together, these processes are associated with the downward transport of dust into the surface layer through vertical coupling at the frontal leading edge. This corresponds to a surface PM₁₀ peak with little temporal delay relative to the onset of frontal influence. Conversely, the March 2022 event is characterized by a relatively stable LLJ core and a persistent capping inversion that acts as a structural barrier, maintaining the dust layer aloft. Persistent wind shear and turbulence below the jet core are associated with sustained elevated transport and temporary aerosol storage prior to the delayed surface response. This configuration decouples the LLJ from the surface, resulting in an approximately 8-hour phase lag between the onset of the surface frontal influence and the PM₁₀ peak (578 μg m^-3). The peak occurs during the transient breakdown of the capping inversion, coinciding with the downward redistribution of the elevated aerosol layer. Wind hodographs indicate that inertial oscillations contribute to the maintenance of these dust-laden LLJs following frictional decoupling. Overall, LLJ evolution is associated with either rapid downward redistribution or elevated storage with delayed surface release, depending on the jet height relative to boundary-layer stability. The results provide an observational basis for refining boundary-layer parameterizations in numerical weather prediction and air quality models.

Low-level jets (LLJs) significantly influence aerosol vertical transport and the resulting surface air quality. This study utilizes coherent Doppler wind lidar observations to characterize the impact of LLJ dynamics on vertical aerosol redistribution during two typical dust episodes over Hefei, East China. Results show that the vertical trajectory of the LLJ core is associated with dust transport through the combined effects of mechanical shear and thermal stability. In the April 2021 event, the northwesterly jet core exhibits a dynamic vertical evolution, descending from 2.5 km to 0.3 km before reascending to 1.0 km by the time of the surface PM₁₀ peak (410 μg m^-3). This movement maintains enhanced wind shear (> 0.04 s^-1) and associated mechanical turbulence at the jet's lower interface. Together, these processes are associated with the downward transport of dust into the surface layer through vertical coupling at the frontal leading edge. This corresponds to a surface PM₁₀ peak with little temporal delay relative to the onset of frontal influence. Conversely, the March 2022 event is characterized by a relatively stable LLJ core and a persistent capping inversion that acts as a structural barrier, maintaining the dust layer aloft. Persistent wind shear and turbulence below the jet core are associated with sustained elevated transport and temporary aerosol storage prior to the delayed surface response. This configuration decouples the LLJ from the surface, resulting in an approximately 8-hour phase lag between the onset of the surface frontal influence and the PM₁₀ peak (578 μg m^-3). The peak occurs during the transient breakdown of the capping inversion, coinciding with the downward redistribution of the elevated aerosol layer. Wind hodographs indicate that inertial oscillations contribute to the maintenance of these dust-laden LLJs following frictional decoupling. Overall, LLJ evolution is associated with either rapid downward redistribution or elevated storage with delayed surface release, depending on the jet height relative to boundary-layer stability. The results provide an observational basis for refining boundary-layer parameterizations in numerical weather prediction and air quality models.