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Enhancement of PM 2.5 Concentrations by Aerosol‐Meteorology Interactions Over China
Author(s) -
Zhang Xin,
Zhang Qiang,
Hong Chaopeng,
Zheng Yixuan,
Geng Guannan,
Tong Dan,
Zhang Yuxuan,
Zhang Xiaoye
Publication year - 2018
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2017jd027524
Subject(s) - aerosol , atmospheric sciences , relative humidity , environmental science , weather research and forecasting model , meteorology , wind speed , climatology , planetary boundary layer , geography , physics , geology , turbulence
Aerosol‐meteorology interactions can change surface aerosol concentrations via different mechanisms such as altering radiation budget or cloud microphysics. However, few studies investigated the impacts of different mechanisms on temporal and spatial distribution of PM 2.5 concentrations over China. Here we used the fully coupled Weather Research and Forecasting model with online chemistry (WRF‐Chem) to quantify the enhancement of PM 2.5 concentrations by aerosol‐meteorology feedback in China in 2014 for different seasons and separate the relative impacts of aerosol radiation interactions (ARIs) and aerosol‐cloud interactions (ACIs). We found that ARIs and ACIs could increase population‐weighted annual mean PM 2.5 concentration over China by 4.0 μg/m 3 and 1.6 μg/m 3 , respectively. We found that ARIs play a dominant role in aerosol‐meteorology interactions in winter, while the enhancement of PM 2.5 concentration by ARIs and ACIs is comparable in other three seasons. ARIs reduced the wintertime monthly mean wind speed and planetary boundary layer (PBL) height by up to 0.1 m/s and 160 m, respectively, but increased the relative humidity by up to 4%, leading to accumulation of pollutants within PBL. Also, ARIs reduced dry deposition velocity of aerosols by up to 20%, resulting in an increase in PM 2.5 lifetime and concentrations. ARIs can increase wintertime monthly mean surface PM 2.5 concentration by a maximum of 30 μg/m 3 in Sichuan Basin. ACIs can also increase PM 2.5 concentration with more significant impacts in wet seasons via reduced wet scavenging and enhanced in‐cloud chemistry. Dominant processes in PM 2.5 enhancement are also clarified in different seasons. Results show that physical process is more important than chemical processes in winter in ARIs, while chemical process of secondary inorganic aerosols production may be crucial in wet seasons via ACIs.