Two Typical Patterns of Regional PM2.5 Transport for Heavy Air Pollution Over Central China: Rapid Transit Transport and Stationary Accumulation Transport

Abstract

The regional transport of air pollutants has been identified as a critical factor that affects air quality over downwind receptor areas; however, the regional transport patterns for air pollution episodes remain poorly understood. In this study, we identified two distinct patterns of regional transport: rapid transit transport (RTT) and stationary accumulation transport (SAT), both of which induced severe PM2.5 pollution episodes in central China during 2015–2020. The differences and similarities between the two regional transport patterns of air pollution were characterized by their influencing meteorological factors. Similar meteorological conditions trigger the RTT and SAT, with a high-PM2.5 concentration air mass from the upstream regions transported to the Twain-Hu Basin (THB) by the strong northerly winds with a southward advance of cold air mass. The average rate of increase in the PM2.5 concentration of the RTT (12.5 μg/m3/h) is more than that of the SAT (5.7 μg/m3/h). However, meteorological conditions evolved differently in RTT and SAT. For RTT with the fast passage of cold air, the THB is located behind the strong cold front during the later stage, and these events rapidly ended owing to the northerly winds and wet scavenging of precipitation. For SAT with the slow cold air accumulation, the THB is mainly occupied by a weak high-pressure system with low wind speeds, strong descending airflow, and a low atmospheric boundary layer height, trapping the air pollutants accumulated in the THB and resulting in persistent heavy pollution incidents. This study provides new insights into the meteorological mechanism underlying the formation of severe air pollution episodes over a receptor region owing to the regional transport patterns of air pollutants.

Improving Below‐Cloud Scavenging Coefficients of Sulfate, Nitrate, and Ammonium in PM2.5 and Implications for Numerical Simulation and Air Pollution Control

“…As reported by Y. Wang et al (2022), washout could reduce the haze duration from 73 to 28 hr. To quantify the impact of BS, our schemes were used to estimate the aerosol concentration abatements as BS was the major clearing way at that moment.…”

“…It often suffers severe PM 2.5 pollution in winter (Yan et al., 2021). These pollution episodes are mainly dissipated by washout as cold and warm air masses mix (Hu et al., 2021; Y. Wang et al., 2022). As reported, BS can remove 55% of PM 2.5 over CC (Hu et al., 2021).…”

Application of stable index and transport index for regional air pollution over Twain-Hu Basin

“…In addition, the average value of PM 2.5 concentration in Hubei is the highest under the control of the P2 type, while that in Hunan is the highest under the P4 type. It is closely related to the different geographical locations of Hubei and Hunan, which are located in different locations of the weather system, and the stations in Hubei are located in the main channels of pollutant regional transmission (Bai et al, 2022;Wang et al, 2022). The average concentration of PM 2.5 under the influence of P3 type is lower than that of P2 type and P4 type, but higher than that of P1 type, showing a consistent feature at each station.…”