Decadal variability in the occurrence of wintertime haze in central eastern China tied to the Pacific Decadal Oscillation

Abstract

Haze is a serious issue in China with increasing concerns, and understanding the factors driving decadal-scale variations in haze occurrence is relevant for government policymaking. Using a comprehensive observational haze dataset, we demonstrate notable decadal fluctuations in the number of haze days (HD) during winter in central eastern China, showing a decline since the mid-1980s. The leading mode of the wintertime HD features an increasing trend for 1959–2012 in eastern China, highly correlated with China’s gross domestic product (GDP) that represents increasing trend of pollutant emissions, and to a lesser extent meteorological factors. The second mode shows decadal variations in central eastern China associated with Pacific Decadal Oscillation (PDO). Observations and numerical simulations suggest that Mongolia High and corresponding descending motion tend to be enhanced (weakened) in central eastern China during the positive (negative) phase of PDO. With PDO shifting towards a negative phase, the weakened Mongolia High and ascending anomalies make the air unstable and conduce to the spread of pollutants, leading to the decline in the wintertime HD over central eastern China since the mid-1980s. Based on above physical mechanisms, a linear model based on PDO and GDP metrics provided a good fit to the observed HD.

Inter‐annual variation of the spring haze pollution over the North China Plain: Roles of atmospheric circulation and sea surface temperature

“…As shown in Figure 5, there is a significant decreasing trend in the DECI during the period from 1979 to 2013, which is highly consistent with the previous findings observed for the winter haze events (e.g., . Furthermore, it is noted that the haze variability in China can be mathematically broken into three components based on the case we are analysing here: a long-term trend, inter-decadal variation, and inter-annual variations (Cohen, 2014; Zhao et al, 2016). Zhao et al (2016) showed that long-term trend of the winter haze reduction over eastern China is closely related to the China's economic development and the inter-decadal timescale variation has a close relationship with the SST anomalies related to the PDO.…”

“…Furthermore, it is noted that the haze variability in China can be mathematically broken into three components based on the case we are analysing here: a long-term trend, inter-decadal variation, and inter-annual variations (Cohen, 2014; Zhao et al, 2016). Zhao et al (2016) showed that long-term trend of the winter haze reduction over eastern China is closely related to the China's economic development and the inter-decadal timescale variation has a close relationship with the SST anomalies related to the PDO. However, in our case, our findings are quite different with respect to the spring DECI on the inter-annual timescale.…”

Numerical simulations of the effects of regional topography on haze pollution in Beijing

“…Previous studies have suggested that there is a close relationship between the occurrence of winter haze pollution in the Beijing-Tianjin-Hebei region and atmospheric circulation at middle to high latitudes over a long-term perspective 35–37 . In addition, on interannual time scales, the air pollution across central and eastern China or even South Asia in the winter and summer is closely related to the East Asian winter and summer monsoons, respectively 38–45 .…”

Black Carbon Amplifies Haze Over the North China Plain by Weakening the East Asian Winter Monsoon

“…Wang et al (2015) by Arctic sea ice variability, a finding confirmed by Zou et al (2017). Zhao et al (2016) also found that the Pacific Decadal Oscillation can influence the number of winter haze days in central-eastern China, with a statistically significant correlation coefficient of 0.66 between the Pacific Decadal Oscillation index and wintertime haze days. Li, Zhang, et al (2016) reported a statistically significant correlation coefficient of À0.41 between East Asian winter monsoon index and wintertime fog-haze days.…”