Impact of Climate Change on Siberian High and Wintertime Air Pollution in China in Past Two Decades

Abstract

China has suffered severe air pollutions during wintertime as national industrialization and urbanization have been increasingly developed in the past decades. Recent studies suggest that climate change has important impacts on extreme haze events in northern China. This study uses reanalysis datasets to analyze the trend and variability of Siberian High (SiH) intensity, and its relationship with the Arctic temperature and sea ice cover (SIC) in past two decades. The results show that Arctic is warming accompanied by a rapid decline of SIC, while Eurasia is cooling and SiH intensity is gradually enhancing. The statistics illustrates that the SiH has a significantly positive correlation to the temperature (R = 0.70), and a significant anticorrelation to the SIC (R = −0.69), and this is because the warming Arctic and the reducing SIC enhanced the SiH. The enhanced SiH leads to strengthened northerly winds in the North China Plain (NCP). The WRF‐Chem model calculation reveals the strengthened northerly winds during the stronger SiH period in January 2016 produce a significant decrease in PM2.5 (particulate matter with aerodynamic diameter less than 2.5 µm) concentrations by 100–200 µg m−3 than that during the weaker one in January 2013. A sensitivity calculation figures out the reduction of PM2.5 concentrations due to a decrease of 50% in emissions is comparable to changes from the weak SiH condition to the strong SiH condition, suggesting that extreme climate variability in the past few years could have an equivalent impact as a consequence of a large emission reduction on wintertime air pollution in the NCP.

Retrospective analysis of 2015–2017 wintertime PM<sub>2.5</sub> in China: response to emission regulations and the role of meteorology

“…Those studies (e.g., Li et al, 2016;Zuo et al, 2015) revealed that wintertime foghaze days across central and eastern China have a close relationship with the East Asian winter monsoon; in addition, significant weakening of the Siberian high and East Asian trough are closely correlated with warm events which boost air pollution. Consistent with our study, Zhao et al (2018) noted that a stronger Siberian high period in January 2016 produced a significant decrease in PM 2.5 concentrations relative to those during weaker periods in other years. The abovementioned studies emphasized that climate change factors and the impacts of emission changes are still difficult to evaluate.…”

East Asian Monsoon Variability Since the Sixteenth Century

“…On instrumental time scales since 1950, the EAM has been shown to interact with other regional climate phenomena, including the El Niño–Southern Oscillation (ENSO; e.g., D'Arrigo et al, ; Xie et al, ), Pacific and Indian ocean sea surface temperatures (SST; Li et al, ; Wu et al, ) and the Arctic Oscillation (AO; Zhao et al, ). ENSO, the variation of zonal winds and SST over the tropical Pacific, has a strong but temporally variable relationship with the EAM, where in general, positive ENSO (El Niño) events cool the IPWP and weaken both summer and winter monsoons.…”

Relationship between East Asian Cold Surges and Synoptic Patterns: A New Coupling Framework

“…It is reported that climate change is "perhaps the single greatest challenge confronting the Asia-Pacific region, and its more than 4 billion people [17]". A recent study has indicated that SH intensity is enhancing [18], favoring a southward intrusion of cold air towards East Asia [19], though global warming trends are also expected to affect the SH. The warming trend over the period 1901-2009 is particularly strong for the semiarid area of Asia, with an increase of 2.4 • C during the cold season between November and March.…”