[Effects of Major Urban Meteorological Factors on Near-surface Ozone on the Northern Slope of the Tianshan Mountains from 2018 to 2022].

Abstract

The analysis of the ozone trend after removing the influence of meteorological factors is extremely important to evaluate the implementation effect of air pollution prevention and control policies. The effects of meteorological factors on near-surface ozone concentrations in four cities （Shihezi, Changji, Wujiaqu, and Urumqi） with serious air pollution in the economic zone of the northern slope of the Tianshan Mountains in the past five years （2018-2022） were investigated using a combination of the KZ filtering method and multiple linear stepwise regression. The results showed that the seasonal component of O₃-8h contributed the most （≥69.3%） to the total variance of the original O₃-8h sequence, and the long-term component contributed the least （≤1.9%） to the total variance, indicating that near-surface ozone concentration （in the cities） was mainly affected by the changes in seasonal and short-term meteorological conditions. O₃ was significantly positively correlated with daily maximum temperature and negatively correlated with relative humidity and barometric pressure. O₃-8h concentrations increased significantly at elevated wind speeds, which may have been due to the titration reaction of O₃ with locally emitted NO under quiescent conditions, whereas faster regional transport replenished locally consumed O₃. Changes in meteorological factors contributed 33%-61% percent to the change in O₃ concentration, and the meteorological conditions of Aiqing Poetry Hall and the Training Base contributed less to the O₃-8h concentration, 48% and 33%, respectively, whereas the meteorological conditions of other stations had a greater impact. Using the analysis of changes in O₃ and NO₂ concentrations before and after the removal of meteorological factors, the effect of meteorological factors on the sensitivity partitioning of O₃ production could be observed. The ozone sensitivity of Changji （the Government Affairs Center of the New District）, Wujiaqu （the Nongshui Building）, and Urumqi （the monitoring station and Midong District Environmental Protection Bureau） tended to be VOCs-controlled, whereas in the sites in Shihezi （the Aiqing Poetry Museum） and Urumqi （the training base） the ozone sensitivity was closer to mixed sensitivity or NO_x-controls. This study helps to recognize the influence of meteorological factors on O₃ concentration in major cities in the economic zone of the north slope of Tianshan Mountain and provides scientific and technological support for the control of atmospheric ozone pollution in Northwest China.