Aircraft study of
secondary aerosols in long-range transported air masses from the North
China Plain by a mid-latitude cyclone
Peng Sun1,2*, Wei Nie1,2,
Xuguang Chi1,2, Xin Huang1,2,
Chuanhua Ren1,2, Likun Xue2,3, Ye
Shan3, Liang
Wen3, †, Hongyong
Li3, Tianshu Chen3, Yanbin
Qi4,5, Jian Gao6, Qi
Zhang7 and Aijun Ding1,2*
1 Joint International Research Laboratory of
Atmospheric and Earth System Sciences, School of Atmospheric Sciences,
Nanjing University, Nanjing 210023, China.
2 Jiangsu Provincial Collaborative Innovation Center
for Climate Change, Nanjing 210023, China.
3 Environment Research Institute, Shandong University,
Ji’nan, Shandong, China
4 Jilin Province Technology Center for Meteorological
Disaster Prevention, Changchun 130062
5 Joint Open Laboratory for Weather Modification of
China Meteorological Administration/People’s Government of Jilin
Province, Changchun 130062, China;
6 State Key Laboratory of Environmental Criteria and
Risk Assessment, Chinese Research Academy of Environmental Sciences,
Beijing, China
7 Department of Environmental Toxicology, University
of California, 1 Shields Ave., Davis, CA 95616, USA
Corresponding author: Peng Sun
(sunpeng@nju.edu.cn);
Aijun Ding (dingaj@nju.edu.cn)
† Now at Leibniz-Institute for Tropospheric Research
(TROPOS), Atmospheric Chemistry Department (ACD), Permoserstraße 15,
04318 Leipzig, Germany
Key Points:
- Aircraft measurements recorded high loadings of sulfate-dominated
secondary aerosols in the free troposphere of the Northeast China.
- Strong changes of secondary aerosols occurred in the fronts-induced
air masses transported by a mid-latitude cyclone.
- Increased sulfate contribution in PM2.5 was mainly
caused by evaporation-induced nitrate losses during the transport.
-
Abstract
Regional transport has been identified as an important contributor to
air pollution. Yet, understanding evolution of aerosol components
associated with synoptic systems remains limited, particularly in China,
where most of the measurement studies were conducted at ground-surface.
In this study, an intensive campaign was designed with an aircraft
measurement in Northeast China (NEC) together with ground-surface
measurements in North China Plain (NCP), to investigate the role that
the mid-latitude cyclone plays in transporting air pollution,
specifically in changing aerosol components during the transport. During
a flight on 30 July 2018, high concentrations of aerosols dominated by
sulfate were observed in the free troposphere (FT), despite low aerosol
loadings dominated by organics in the planetary boundary layer. Model
simulations indicated that pollution in the lower free troposphere (LFT)
was transported directly from North Hebei by warm and moist air masses,
while pollution in the higher free troposphere (HFT) was influenced by
the warm conveyor belt (WCB), which transported aerosols from the NCP
and lifted them into the HFT. Both particulate nitrate and sulfate were
formed productively due to strong emissions and high atmospheric
oxidizing capacity in the NCP. During the transport, sulfate
concentrations stayed relatively constant while nitrate decreased
readily due to evaporation losses, resulting in an increasing
contribution of sulfate but a decreasing contribution of nitrate to
secondary aerosols along the transport path.