Characteristics of ozone variations during summer heat waves in typical cities in the Yangtze River Delta Region from 2014 to 2020
Three cities in the Yangtze River Delta(YRD),Shanghai,Nanjing and Hangzhou,were selected as typical representative cities to analyze the characteristics of ozone(O3)variations during the summer heat waves from 2014 to 2020 based on observations and WRF-CMAQ model.The results showed that the intensity of summer heat waves in the three cities showed an increasing,then decreasing,then increasing trend,with 2016 and 2017 being the years of super heat waves and 2014 and 2018 being the years of weak heat waves.The hourly O3 concentrations during the heat waves showed a"single peak,single valley"pattern,peaking at 13:00 or 14:00 and reaching valley values at 6:00.Interannual variations of the average daily maximum O3 concentrations,the average daytime and nighttime O3 concentrations and Maximum Daily 8-Hour Average O3(MDA8O3)during the heat waves were similar in each city,with a significant decreasing trend in Shanghai,an increasing and then decreasing trend in Nanjing,and a decreasing trend in Hangzhou in general,and O3 concentrations during the heat waves were characterized by significant phase changes with temperature in each city.The WRF-CMAQ model could well simulate MDA8O3 during the heat waves in the three cities.Model results showed that the variations in meteorological conditions and precursor emissions have different effects on the changes in MDA8O3 during the heat waves in each city.Variations in meteorological conditions dominated the decrease in MDA8O3 during the heat waves in Shanghai,while variations in MDA8O3 in Nanjing were mainly influenced by variations in emissions,and variations in MDA8O3 in Hangzhou were influenced by the combined effects of meteorology and emissions.Meanwhile,persistent high temperature was not the only meteorological factor affecting O3 concentration,mean sea level pressure and wind speed also had a significant effect on MDA8O3 during the heat waves.
O3high-temperature heat wavesYangtze River DeltaWRF-CMAQ
万方数据
