Impacts of Cross-Regional Transport on Ozone Pollution in the Fen-Wei Plain: Insights from Multi-Source Observations and Model Simulation

Overview

This study examines cross-regional ozone transport contributions to surface-level ozone pollution in the Fenwei Plain, leveraging multi-source observational data and model simulation. The research addresses knowledge gaps regarding ozone formation mechanisms in this region by integrating vertical profile measurements, flux data, and volatile organic compound characterization to quantify the relative contributions of different source regions and their interaction with local photochemical sensitivities.

Methods and approach

The investigation employed integrated observational techniques including ozone lidar for vertical profiling, vertical flux measurements, and in situ volatile organic compound component analysis. Source apportionment technology was applied to determine regional contribution percentages to surface ozone enhancement. Ozone precursor sensitivity analysis was conducted to establish linkages between regional transport patterns and local photochemical regimes. Comparative assessment of ozone chemical indicators, specifically the HCHO/NO2 ratio, provided supplementary evidence for sensitivity regime characterization.

Key Findings

Lidar observations identified high-concentration ozone layers exceeding 130 µg/m³ in the vertical profile with downward vertical fluxes exceeding −50 µg/(m²·s), indicating surface-level transport. Volatile organic compound analysis revealed predominance of oxygenated compounds (greater than 300 ppbv) and alkanes (greater than 20 ppbv). Source apportionment attributed 24.99% and 40.02% of surface ozone enhancement to Henan and Hubei regions respectively. Transport from these source regions drove local photochemistry toward a volatile organic compound-limited regime, with HCHO/NO2 ratios declining to 1.73. A demonstrated correlation emerged between varying regional contribution magnitudes and shifts in local ozone precursor sensitivity.

Implications

The quantified regional contributions underscore the significance of cross-regional transport in determining surface ozone pollution severity in the Fenwei Plain, with Hubei and Henan regions representing the dominant external sources. The dynamical relationship between source region contributions and local photochemical sensitivity regimes suggests that effective pollution control requires differentiated strategies accounting for source-specific precursor compositions and their interaction with local atmospheric chemistry. Regional joint prevention and control frameworks should incorporate transport-dependent sensitivity patterns when establishing emission reduction targets, as uniform mitigation approaches may prove ineffective given the spatial heterogeneity of photochemical regimes.