Meteorological Conditions and Weather Classification for Near-Surface Ozone Concentration in Kunming City in Recent Five Years

Guo Xiaomei; Tian Yongli; Yang Jian

doi:10.16765/j.cnki.1673-7148.2025.05.007

Abstract：Based on the ozone(O3)monitoring data and relevant meteorological element data in Kun-ming City from 2017 to 2021,the variation characteristics of ozone concentration and main meteorological influence factors in Kunming in recent five years are analyzed,and the weather system during non-optimal(below the"optimal"level)ozone days is subjectively classified.The results show that,in recent five years,the non-optimal days of ozone in Kunming have shown an increasing trend,and the average ozone concentration and the number of non-optimal ozone days in dry season are higher than those in rainy sea-son.The O3 non-optimal peak period of ozone in the year is from March to April(spring),and the second non-optimal peak of O3 in the year appears in August(summer).Ozone concentration is positively correla-ted to sunshine hours and daily maximum temperature,but negatively to relative humidity.In other words,when it is high temperature,low humidity and strong sunshine,ozone concentration is prone to rise.The weather patterns that cause the non-optimal days of ozone in Kunming at 500 hPa geopotential height mainly include six types,i.e.,the flat westerly type(X,accounting for 35.0%of the total,which is the most),the southwest airflow type in front of the dry south branch trough(N,which is the second most),the northwest airflow type behind the trough(B),the westerly airflow type outside the subtropical high(G),the easterly wind type outside the South China Sea low pressure(D)and the Qinghai-Tibet Plateau high pressure bottom type(Q,accounting for at least 5.7%of the total,but the ozone concentration during the period is the highest).In dry season,the weather types are mainly X,N,B,with westerly wind mainly blowing,and the weather is dry,warm and sunny.However,in rainy season,the weather types are mainly D and Q,and the weather is humid,hot and sunny,accompanied by easterly wind.