RESUMEN
It is of great importance to scientifically evaluate the impact of weather and climate conditions on the occurrence of O3 pollution in order to improve the accuracy of O3 pollution forecastsï¼ as well as to reasonably control and reduce the adverse effects of O3 pollution. The characteristics of O3 concentration and climate background were analyzed based on daily O3 concentration dataï¼ meteorological factorsï¼ and NCEP/NCER reanalysis data from 2006 to 2021 in Shanghai. In additionï¼ the differences in atmospheric circulation situations during years with anomalous O3 concentrations were compared and diagnosed from the perspective of climatology. Additionallyï¼ the monthly O3 concentration prediction model ï¼seasonal autoregressive integrated moving average with exogenous regressorsï¼ SARIMAXï¼ was further established by adding the key meteorological factors. The results indicated that both the whole-year average and summer half-year average O3 concentrations in Shanghai were increasing with fluctuationï¼ and the summer half-year average was much higher than the annual averageï¼ up to 36.2%. Furthermoreï¼ there was a significant negative correlation between O3 concentration and wind speed ï¼correlation coefficient of -0.826ï¼ and a significant positive correlation with the frequency of static wind and the number of days in which the low cloud cover was less than 20% ï¼correlation coefficients of 0.836 and 0.724ï¼ respectivelyï¼. The monthly mean O3 concentration had a clear periodicityï¼ showing a pattern with a high concentration in the middle period ï¼April to Septemberï¼ and a low concentration at the beginning and end of the periods. High O3 concentration years ï¼2013-2021ï¼ were accompanied by more polluted daysï¼ lower average wind speedï¼ more small wind ï¼≤1.5 m·s-1ï¼ daysï¼ more days of low cloud cover of less than 20%ï¼ more days of high temperatureï¼ higher direct solar radiationï¼ and more sunshine hours. When the location of the stronger West Pacific subtropical high was westward and southward in the summer half-yearï¼ Shanghai was influenced by an anomalous westerly windï¼ which was not conducive to the transportation of clean air from the sea to Shanghai and thus led to the high concentration of O3 pollution. When the long wave radiation emitted from the ground was low in the summer half-yearï¼ it was favorable for the increase in ground temperature and caused a high concentration of O3 pollution. Adding direct solar radiationï¼ maximum temperatureï¼ and wind speed as exogenous variables to the monthly O3 forecast model could significantly improve the effectiveness of the monthly forecastï¼ with the root mean square error decreasing by 47.7% ï¼from 22 to 11.5ï¼ and the correlation coefficient increasing by 11.2% ï¼from 0.819 to 0.911ï¼ï¼ which could be applied to the practical prediction of monthly O3 concentration.
RESUMEN
We use daily aerosol particulate matter<10 µm (PM10) concentration data from 2006 to 2016 in Shanghai along with meteorological elements (wind and temperature), atmospheric stability, temperature inversion, and upper atmosphere circulation data, to analyze the variation characteristics of the PM10 concentrations and differences of the winter climate background. We establish a multivariate linear stepwise regression equation, and also compare and analyze differences in the upper atmospheric circulation by selecting the years with the highest and lowest PM10 concentrations. The results showed an oscillating downward trend in the annual average concentrations of PM10 in Shanghai, whereas seasonally, PM10 concentrations were relatively high in winter and showed two peaks with a low in between. PM10 concentrations were negatively correlated with the daily average wind speed and the daily mixing layer height at 20:00, and positively correlated with the frequency of northwest wind, the mean daily temperature, and the frequency of stable weathers and thermal inversion at 20:00. When the 500 hPa height field in the northern part of China was a positive anomaly in winter, a warm winter prevailed and led to high PM10 concentrations. When the 500 hPa height field was a negative anomaly, cold air frequently moved southward to result in relatively low temperatures, which caused relatively low PM10 concentrations. When the wind field at 850 hPa was easterly, the wind speed was relatively large and resulted in relatively low PM10 concentrations.