Tropospheric ozone (O 3 ) is a trace gas playing important roles in atmospheric chemistry, air quality and climate change. In contrast to North America and Europe, longterm measurements of surface O 3 are very limited in China. We compile available O 3 observations at Mt. Tai -the highest mountain over the North China Plain -during 2003-2015 and analyze the decadal change of O 3 and its sources. A linear regression analysis shows that summertime O 3 measured at Mt. Tai has increased significantly by 1.7 ppbv yr −1 for June and 2.
Understanding new particle formation and their subsequent growth in the troposphere has a critical impact on our ability to predict atmospheric composition and global climate change. High pre-existing particle loadings have been thought to suppress the formation of new atmospheric aerosol particles due to high condensation and coagulation sinks. Here, based on field measurements at a mountain site in South China, we report, for the first time, in situ observational evidence on new particle formation and growth in remote ambient atmosphere during heavy dust episodes mixed with anthropogenic pollution. Both the formation and growth rates of particles in the diameter range 15–50 nm were enhanced during the dust episodes, indicating the influence of photo-induced, dust surface-mediated reactions and resulting condensable vapor production. This study provides unique in situ observations of heterogeneous photochemical processes inducing new particle formation and growth in the real atmosphere, and suggests an unexpected impact of mineral dust on climate and atmospheric chemistry.
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