[Prediction of Ozone Pollution in Sichuan Basin Based on Random Forest Model].

ABSTRACT

To study the long-term variation in ozone (O3) pollution in Sichuan Basin,the spatiaotemporal distribution of O3 concentrations during 2017 to 2020 was analyzed using ground-level O3 concentration data and meteorological observation data from 18 cities in the basin. The dominant meteorological factors affecting the variation in O3 concentration were screened out,and a prediction model between meteorological factors and O3 concentration was constructed based on a random forest model. Finally,a prediction analysis of O3 pollution in the Sichuan Basin urban agglomeration during 2020 was carried out. The results showed that① O3 concentrations displayed a fluctuating trend during the period from 2017 to 2020,with a downward trend in 2019 and a rebound in 2020. ② The fluctuating trend of O3 concentration was significantly influenced by relative humidity,daily maximum temperature,and sunshine hours,whereas wind speed,air pressure,and precipitation had less impact. The linear relationships between meteorological factors were different. Air pressure was negatively correlated with other meteorological factors,whereas the remaining meteorological factors had a positive correlation. ③ The goodness of fit statistics (R2) between the predicted and actual values of the O3 prediction model constructed based on random forest demonstrated a strong predictive performance and ability to accurately forecast the long-term daily variations in O3 concentration. The random forest O3 prediction model exhibited excellent stability and generalization capability. ④ The prediction analysis of O3 concentrations in 18 cities in the basin showed that the explanation rate of variables in the prediction model reached over 80% in all cities (except Ya'an),indicating that the random forest model predicted the trend of O3 concentration accurately.