Linkages between the atmospheric transmission originating from the North Atlantic Oscillation and persistent winter haze over Beijing

• Published in: Atmospheric Chemistry and Physics
• Main Authors: M. Li, Y. Yao, I. Simmonds, D. Luo, L. Zhong, L. Pei
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2021
• Subjects: Physics; QC1-999; Chemistry; QD1-999; North Atlantic; North Atlantic oscillation
• Online Access: https://doi.org/10.5194/acp-21-18573-2021; https://doaj.org/article/cc42b375b25246c7ab9c965c9418c7e4

In this study, the persistent winter haze that occurred over Beijing during 1980 to 2016 is examined using reanalysis and station data. On both interannual and daily-to-weekly timescales, the winter haze weather in Beijing is found to be associated with a pronounced atmospheric teleconnection pattern from the North Atlantic to Eurasia (Beijing). A positive western-type North Atlantic Oscillation (WNAO + ) phase and a positive East Atlantic/West Russia (EA/WR + ) phase are observed as part of this teleconnection pattern (an arched wave train). This study focuses on the role of the WNAO pattern, because the WNAO + pattern acts as the origin of the atmospheric transmission, 8–10 d before the persistent haze events. Further analyses reveal that the WNAO + pattern can increase the number of haze days and persistent haze events on interannual and daily-to-weekly timescales. Specifically, strong WNAO + winters (above the 95th percentile) can increase the number of haze days and persistent haze events by 26.0 % and 42.3 %, respectively. In addition, a high WNAO index for the 5 d average (above the 95th percentile) predicts a 16.9 % increase in the probability of haze days on Day 8 and a higher proportion of persistent haze days compared with an unknown WNAO state. Thus, the WNAO + pattern is as a necessary prior background condition for the formation of the wave train and is a skillful predictor for persistent hazy weather. Corresponding to the WNAO + pattern, intensified zonal wind and a north–south sea surface temperature tripolar mode over the North Atlantic also appear before persistent haze events on the daily-to-weekly timescale. On the interannual timescale, winters with a greater number of persistent haze days are also associated with a tripolar sea surface temperature (SST) mode over the North Atlantic that is situated farther northward.