生态环境学报2026，Vol.35Issue(4)：575-585,11.DOI:10.16258/j.cnki.1674-5906.2026.04.008
夏秋季热带气旋对珠三角O3浓度的影响
The Influence of Summer and Autumn Tropical Cyclones on O3 Concentration at Pearl River Delta
摘要
Abstract
The Pearl River Delta(PRD),one of the three major urban agglomerations in China,contains nine cities extending from the south to central part of Guangdong Province.The O3 concentration and its corresponding exceedance rate in PRD have shown an upward trend in recent years,making it gradually become the primary pollutant in PRD.The underlying mechanisms driving the increase are still being pursued.Studies have indicated that tropical cyclones may be a significant factor influencing O3 pollution in PRD.For instance,Hu et al.(2023)found that the average O3 concentration and exceedance probability in PRD were significantly higher when tropical cyclones originating in western North Pacific moved within 700-4 500 km of PRD.Similarly,Pu et al.(2020)found that in Jiangmen,a city in western PRD,37%of O3 exceedance days between 2015 and 2017 occurred during weather patterns featuring tropical cyclone activity in the western North Pacific or South China Sea.Shen et al.(2023)further indicated that～81%of O3 pollution in Guangdong during summer and autumn was associated with surrounding typhoon activity.Despite the advanced findings,few studies have examined the event evolution from the perspective of integrated atmospheric circulation situation and meteorological conditions.To address this gap,we analyzed multiple tropical cyclone events that evolved in the western North Pacific from 2018 to 2024,with a focus on their impacts on summer and autumn(June to November)O3 concentration in PRD.The used data sources include:1)tropical cyclone information from the Best Track Data from the China Meteorological Administration Tropical Cyclone Data Center,2)meteorological parameters from the Fifth Generation of Global Climate Reanalysis data(ERA5)from European Centre for Medium-Range Weather Forecasts,and 3)the maximum daily 8-hour average(MDA8)of O3 concentration in 21 cities in Guangdong Province from Chinese Ministry of Ecology and Environment(MEE).We first identified 29 tropical cyclones which remained within 1 500 km from Guangzhou(the geographical center of PRD)for over 48 consecutive hours as our research subjects.We set these criteria because previous studies indicate that surface O3 concentrations typically increase within a range of 400-1 500 km from the tropical cyclone center.To clearly illustrate the potential impacts,we selected the week during which a single tropical cyclone exerted the most extensive influence on O3 concentrations as the complete event record period.Specifically,we defined the date when the PRD MDA8 O3 reaches its peak under the influence of a tropical cyclone as Day0,and the three days preceding and following this date as Day-3,Day-2,Day-1,Day1,Day2,and Day3,respectively.Subsequent analyses were conducted based on O3 concentration changes observed during this one-week period.To better assess the impact of tropical cyclones,daily O3 concentration deviation was adopted as an evaluation metric.It is defined as the difference between the daily MDA8 O3 on a given date when affected by a tropical cyclone and the monthly average MDA8 O3 concentration when the date falls within that month.We find that the deviation is mainly positive when tropical cyclone locates within 500-1 800 km of Guangzhou.The averaged positive deviation amounts to 30.3 µg∙m-3,with the maximum deviation reaching up to 115.7 µg∙m-3 which occurs when the tropical cyclone is located in the oceanic area north to Luzon Island,or the oceanic area east and north to Taiwan Island.We also find that under the influence of tropical cyclones,MDA8 O3 generally exhibited a pattern of upward trend followed by a subsequent decline,though the time of reaching peak levels varied.Subsequently,we classified the 29 tropical cyclones into two categories based on their track profiles,i.e.,northwestward and westward paths.Observations revealed that surface O3 is generally higher during the effects of the northwestward tropical cyclones.Moreover,O3 exceedances—daily MDA8 O3 exceeding 120 µg∙m-3—lasted longer and affected a greater number of cities under such circumstances.We also find that MDA8 O3 consistently peaked between Day-1 and Day1,with median value exceeding the summer-autumn averages regardless of the cyclone track path.According to this observation,we designate the period of Day-1 to Day1 as the O3 episode,and defined Day-3 to Day-2 as pre-episode period and Day2 to Day3 as post-episode period.From the pre-episode to the episode,both types of tropical cyclones promote the evolution of near-surface meteorological elements into conditions favorable for O3 photochemical reactions but unfavorable for dispersion diffusion and wet cleaning.Notably,these changes were more pronounced under the influence of northwestward tropical cyclones,as the average total cloud cover reduced by 2 during the 10:00-18:00 period,the surface-level downward solar radiation increased by 90.8 W·m-2,the 2-meter air temperature at 14:00 rose by 1.2℃,the daily average relative humidity decreased by 5%,and the daily average wind speed decreased by 0.8 m·s-1.In contrast,meteorological factors conducive to O3 dissipation typically exhibit more remarkable changes under the influence of the westward tropical cyclones from the episode to the post-episode.This may partly explain the higher near-surface O3 concentrations observed during northwestward tropical cyclone events.Vertically,changes in meteorological factors which are conducive to O3 formation and pollutant accumulation were also observed from the pre-episode to the episode,regardless of the tropical cyclone types.More specifically,relative humidity in 1 000-800 hPa over Guangdong decreased by 6%-12%,while temperatures generally rose by 0.4-1.2℃,as well as diminished ascent or reversed to descent were observed under the influence of northwestward tropical cyclones.These changes exhibited greater magnitude and deeper vertical penetration when compared to westward tropical cyclones.This may represent another potential driver for elevated near-surface O3 concentration in PRD under the influence of northwestward tropical cyclones.From the perspective of large-scale circulation,we observed that during the episode period influenced by both types of tropical cyclones,the lower troposphere over Guangdong is dominated by northerly winds originating from the inland regions,which facilitates pollution transportation.In the latter phase of the episode,the wind field shifts to southerly or easterly flows from the ocean,with enhanced wind speeds,favoring for pollutant dissipation.Our study enhances the understanding of how tropical cyclones affect near-surface O3 concentration,and the corresponding findings are expected to provide valuable insights for forecasting and warning systems regarding O3 pollution during tropical cyclone events.关键词
热带气旋/臭氧浓度/珠三角/气象要素Key words
tropical cyclones/O3 concentration/Pearl River Delta/meteorological elements分类
资源环境引用本文复制引用
张舒婷,王明洁,倪睿婧..夏秋季热带气旋对珠三角O3浓度的影响[J].生态环境学报,2026,35(4):575-585,11.基金项目
广东省基础与应用基础研究基金项目(2024A1515510032) （2024A1515510032）
广东省气象局科学技术研究项目(GRMC2024Q16) （GRMC2024Q16）
