Ozone occurs both in the stratosphere and at ground level. Surface ozone is a man-made air pollutant and has harmful effects on people and the environment. Two dominant patterns of summer ozone pollution were determined. The most dominant pattern in 2017 and 2018 was different from that in previous years. The findings of this study help us to understand the features of surface ozone pollution in eastern China and their relationships with large-scale atmospheric circulations.

The East Asian winter monsoon (EAWM) can be greatly influenced by many factors that can be classified as anthropogenic forcing and natural forcing. Our results show that the increasing anthropogenic emissions in the past decades may have contributed to the weakening of the EAWM, the frequency of occurrence of strong EAWM may have decreased by 45 % due to the anthropogenic forcing, and the anthropogenic forcing is a dominant contributor to the occurrence of a weak EAWM.

Haze pollution in the Beijing–Tianjin–Hebei region has become increasingly more severe and persistent in recent years.This research focused on severe haze during 2014–2016 and examined the impacts of the anticyclonic anomalies over northeastern Asia. The advance and retreat of anticyclonic anomalies over northeastern Asia (AANA) corresponded with the emergence and dissipation of severe haze, illustrating that AANA could be effective forecast indicators for air quality.

Summer surface ozone pollution has rapidly intensified recently, damaging human and ecosystem health. This study aims to examine the large-scale atmospheric circulations associated with the interannual variation in summer surface O₃ pollution in North China based on long-term meteorological observations. The impacts of Arctic sea ice were also revealed. The outcomes may provide a basis for understanding the interannual variation of 0₃ pollution and its seasonal to interannual prediction.

Recently, haze pollution in the North China has been serious and disastrous. The preceding heavy autumn sea ice intensified the early winter haze pollution over North China. The results provide possibilities for the seasonal to interannual prediction of haze pollution that helps to determine whether extra stringent emission control measures are needed to counteract the effect of climate variability.

Our results show that the anthropogenic air pollution over eastern China will increase considerably at the end of 21st century, even though we keep the aerosol emission constant throughout the experiment. Furthermore, estimation shows that the effect of climate change induced by the GHG warming can account for 11%–28% of the changes of anthropogenic air pollution days over this region.

The paleo-East Asian summer monsoon (EASM) is widely reconstructed by precipitation/humidity proxies over East Asia. However, based on numerical simulations over the last millennium, we find that the multi-decadal relationship between the EASM and precipitation over eastern China is non-stationary, which may be attributed to the internal variability of the climate system rather than the external forcings. In contrast, the centennial EASM–precipitation relationship is much more close and stable.

In China, the haze pollution in December has become increasingly serious over recent decades. The relationship between the snow cover and the December haze days was analyzed. This relationship significantly strengthened after the mid-1990s, which is attributed to the effective connections between the snow cover and the Eurasian atmospheric circulations.

The number of winter haze days over the north-central North China Plain in 2014 was largest in the past 30 years. With the anticyclone circulation over North China taken as an intermediate, the positive phases of the east Atlantic/west Russia, western Pacific, and Eurasian patterns led to a larger number of haze days in 2014. The related external forcing included preceding autumn Arctic sea ice, winter and pre-autumn surface temperature, and pre-autumn sea surface temperature in the Pacific.

Recently, the winter haze pollution over the north central North China Plain has become severe. By treating the year-to-year increment as the predictand, two new statistical schemes were established using the multiple linear regression and the generalized additive model approaches. After cross validation, both of these models could capture the interannual and interdecadal trends and the extremums successfully. Independent tests for 2014 and 2015 also confirmed the good predictive skill.