Associations between winter atmospheric teleconnections in drought and haze pollution over Southwest China.

In the early 21st century, Southwest China (SWC) frequently experienced extreme droughts and severe haze pollution events. Although the meteorological causes of these extreme droughts have been widely investigated, previous studies have yet to understand the causes of haze pollution events over SWC. Moreover, the associations between winter atmospheric teleconnections during drought and haze pollution event across SWC has received negligible attention and therefore warrants investigation. This study examines the associations between the atmospheric teleconnections with respect to winter droughts and winter haze pollution over SWC. Our main conclusions are as follows. (1) Winter precipitation and winter haze days (WHD) over SWC had three major fluctuations from 1959 to 2016. (2) The atmospheric circulation pattern over the Eurasian (EU) continent associated with WHD over SWC resembled that of winter droughts over SWC, where both can be characterized by an EU teleconnection pattern. The Arctic Oscillation (AO) mainly induced the atmospheric circulation pattern over the EU continent that is associated with WHD over SWC. (3) The sea surface temperature (SST) and low circulation anomalies in the Pacific and north Atlantic associated with WHD were similar to those associated with winter droughts over SWC. La Niña events and negative phases of the North Atlantic Oscillation (NAO) may induce winter drought and increase the WHD over SWC. (4) Compared with winter drought over SWC, the variation in the WHD was more complex and the factors affecting WHD were more diverse, and winter drought and its related atmospheric circulations were important factors that induced haze pollution over SWC. Overall, this study not only fills a gap in the literature with respect to the associations between the atmospheric teleconnections of winter drought and winter haze pollution over SWC, but also provides an important scientific basis for the development of potential predictions of local monthly haze pollution, which improves the forecast accuracy of local short-term haze pollution and enriches the theoretical understanding of the meteorological causes of local haze pollution.