Meteorological Causes of a Severe Pollution Weather Process in Shaoyang Area.

Based on the monitoring data of air quality and conventional meteorological data in Shaoyang City, a severe pollution weather process in Shaoyang from December 25, 2023 to January 1, 2024 was analyzed from the aspects of changes in pollutant concentration, circulation background, and changes in various meteorological elements. The results show that this severe pollution weather process was a compound pollution process caused by accumulation of local pollutants and transportation of external pollutants, during which the primary pollutant was PM2.5. During the accumulation stage, the ground was controlled by a uniform pressure field, and the conditions of atmospheric diffusion were poor. During the outbreak stage, the wind on the ground was from the northeast, which was conducive to the input of upstream pollution clusters into the city. Pollutant concentration was inversely correlated with daily average sea-level pressure, and positively correlated with daily average temperature. Wind speed and direction were closely related to PM2.5 concentration. During the accumulation stage, the ground was mainly dominated by weak winds, and the conditions of atmospheric diffusion were poor. During the outbreak stage, the continuous northeastward wind continuously transported upstream pollutants to Shaoyang area. Local pollutants accumulated in the previous stable weather process and the terrain led to the outbreak of local pollution. [ABSTRACT FROM AUTHOR]