Analysis of Ozone Formation Sensitivity and Meteorological Drivers in Typical Ecological Functional Areas:A Case Study of the Qiandao Lake Area
The region of the Qiandao Lake is a significant natural reserve in China,representing a typical ecological functional zone,in which ozone(O3)frequently becomes the primary air pollutant.However,the O3 formation sensitivity therein remains unclear.Using the TROPOMI measurements coupled with the O3 formation indicators,i.e.,the ratio(FNR)of formaldehyde and nitrogen dioxide tropospheric vertical columns,the spatiotemporal characteristics of the O3 formation sensitivity regimes in the region of the Qiandao Lake from 2019 to 2021 were quantitatively investigated.The results showed that the FNR values in the region of the Qiandao Lake increased year by year and were significantly higher than those in downtown Hangzhou.On this basis,the NOx-limited regime in the Qiandao Lake area expanded year by year,starting from 2019,it gradually spread from the southwest to the northeast and had basically covered the Qiandao Lake area by 2021.In summer,the O3 formation in the Qiandao Lake was typically NOx-limited,while,in other seasons,that was limited by VOCs-NOx or NOx.By introducing meteorological reanalysis data,we found that FNR had a strong positive correlation with temperature(r= 0.8),a weak positive correlation with relative humidity,and a weak negative correlation with wind speed and cloud liquid water content.When the temperature was higher than 7.0℃,the wind speed was less than 6.2 m/s,the cloud liquid water content was less than 5.5×10-5 g/m3,and the relative humidity was greater than 57.5%,the O3 formation tended to be NOx-limited.In addition,compared with the O3 formation in Hangzhou,that in the Qiandao Lake region was more sensitive to meteorological parameters.Our results have important implications for O3 pollution mitigation in typical ecological functional zones in China.