2022年8月重庆月最高气温达41.3℃,高温日数长达28 d,在此高温天气下8月重庆市区臭氧未出现超标情况,7月整体气温低于8月,出现7 d臭氧超标的情况.利用观测资料、天气研究与预报(Weather Research and Forecasting,WRF)模式,对此现象进行分析,并综合探讨不同片区臭氧与气象条件的关系,结果表明:(1)8月的气温和边界层高度偏高、风速偏大,而相对湿度偏低,这可能有利于8月臭氧污染状况改善.整体来看,重庆臭氧质量浓度随气温和边界层高度升高均呈现先升高再降低的趋势,当气温高于30℃、边界层高度高于1 000 m、相对湿度低于59％、风速小于6.3 m·s-1时,臭氧质量浓度及超标率均显著上升,而当气温、边界层高度、相对湿度、风速分别超过39℃、2 800 m、59％、6.3 m.s-1时,臭氧质量浓度及超标率均显著下降.(2)主城区和郊区县(区)的气温分别超过38℃和37℃后,臭氧质量浓度升幅变小或出现下降,个别县(区)气温为38～40℃时,臭氧质量浓度仍保持上升趋势.(3)沙坪坝区和长寿区在污染日臭氧和边界层高度2 h升幅峰值同时出现在11时或13时,合川区和荣昌区在污染日臭氧和边界层高度2 h升幅峰值出现时间不一致.研究成果可为重庆夏季臭氧污染的预测、防控和管控提供参考.
Characteristics of ozone under different meteorological conditions in Chongqing during summer
The highest monthly temperature in Chongqing reached 41.3 ℃ in August 2022,and the hot weather lasted for 28 d.Under the high-temperature weather,the ozone does not exceed the standard in Chongqing city in August;while the overall temperature in July is lower than that in August,there are 7 ozone pollution days.By using observations and the WRF(Weather Research and Forecasting)model,this phenomenon is analyzed and the relationship between ozone and meteorological conditions in different areas is comprehensively explored.The results are as follows.(1)The temperature,boundary layer height and wind speed in August are relatively high,while the relative humidity is relatively low,which may be conducive to the improvement of ozone pollution in August.On the whole,the mass concentration of ozone in Chongqing first increases and then decreases with the increase of air temperature and boundary layer height.When the air temperature is higher than 30 ℃,the boundary layer height is higher than 1 000 m,the relative humidity is lower than 59％and the wind speed is lower than 6.3 m·s-1,the mass concentration and excess rate of ozone go up significantly.However,when the air temperature,boundary layer height,relative humidity and wind speed exceed 39 ℃,2 800 m,59％and 6.3 m·s-1,respectively,the mass concentration and excess rate go down significantly.(2)When the temperature in the main urban area and suburban counties(districts)exceed 38 ℃ and 37 ℃,respectively,the increase in the mass concentration of ozone becomes smaller or the mass concentration appears to decline;when the temperature in several counties(districts)is between 38 and 40 ℃,the mass concentration still maintains an upward trend.(3)On pollution days,the 2-h peak of increase of ozone and boundary layer height in Shapingba and Changshou districts occurs at 11:00 or 13:00 at the same time,while that in Hechuan and Rongchang districts occurs at different times.The study provides reference for the prediction,prevention and control of summer ozone pollution in Chongqing.
high temperatureboundary layer heightmass concentration of ozonemeteorological condition
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