Influence of Synoptic-Scale Systems on the Vertical Distribution of Aerosols During a Topographic Dynamic Disturbance

The Beijing–Tianjin–Hebei region of China features a unique topographic structure. Influenced by synoptic-scale systems, the region’s atmospheric strata over the plains are distinct. This study utilizes ground aerosol data, automatic meteorological monitoring station data, and lidar data on extinction coefficients and depolarization ratios from three stations aligned north–south in the Beijing–Tianjin–Hebei Plain. Additionally, high-resolution (1° × 1°) reanalysis data from the National Centers for Environmental Prediction Final Analysis (NCEP-FNL) are employed. We analyze the vertical atmospheric structure and variations in vertical aerosol structure within this dynamic atmospheric framework in response to ongoing disturbances from weak synoptic-scale systems. Findings indicate that as cold air shifts eastward, the eastern part of the Beijing–Tianjin–Hebei Plain becomes more pressurized than the west, generating easterly winds. These winds, upon nearing the Taihang Mountains, significantly reduce near-surface PM2.5 and PM10 concentrations. Near-surface pollutants are lifted to higher altitudes by the combined upward motion of the easterly wind, topography, and synoptic-scale ascent preceding upper-level troughs. Subsequent weak descending motions post-trough passage return high-altitude pollutants to lower levels. The result of these two dynamic interactions—an M-shaped vertical aerosol structure—emerges over the plain east of the Taihang Mountains. This study’s outcomes contribute to understanding how disturbances from weak synoptic-scale systems affect aerosol structures horizontally and vertically under the unique topographical conditions of the Beijing–Tianjin–Hebei region.