10.1021/acs.est.6b03010.s001
Lin Zhang
Lin
Zhang
Jingyuan Shao
Jingyuan
Shao
Xiao Lu
Xiao
Lu
Yuanhong Zhao
Yuanhong
Zhao
Yongyun Hu
Yongyun
Hu
Daven K. Henze
Daven K.
Henze
Hong Liao
Hong
Liao
Sunling Gong
Sunling
Gong
Qiang Zhang
Qiang
Zhang
Sources
and Processes Affecting Fine Particulate Matter
Pollution over North China: An Adjoint Analysis of the Beijing APEC
Period
American Chemical Society
2016
North China
Processes Affecting Fine Particulate Matter Pollution
PM 2.5 events
Hourly surface measurements
NH
emission
PM 2.5
PM 2.5 concentrations
Beijing APEC Period
aerosol
model
2016-07-19 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Sources_and_Processes_Affecting_Fine_Particulate_Matter_Pollution_over_North_China_An_Adjoint_Analysis_of_the_Beijing_APEC_Period/3507254
The
stringent emission controls during the APEC 2014 (the Asia-Pacific
Economic Cooperation Summit; November 5–11, 2014) offer a unique
opportunity to quantify factors affecting fine particulate matter
(PM<sub>2.5</sub>) pollution over North China. Here we apply a four-dimensional
variational data assimilation system using the adjoint model of GEOS-Chem
to address this issue. Hourly surface measurements of PM<sub>2.5</sub> and SO<sub>2</sub> for October 15-November 14, 2014 are assimilated
into the model to optimize daily aerosol primary and precursor emissions
over North China. Measured PM<sub>2.5</sub> concentrations in Beijing
average 50.3 μg m<sup>–3</sup> during APEC, 43% lower
than the mean concentration (88.2 μg m<sup>–3</sup>)
for the whole period including APEC. Model results attribute about
half of the reduction to meteorology due to active cold surge occurrences
during APEC. Assimilation of surface measurements largely reduces
the model biases and estimates 6%–30% lower aerosol emissions
in the Beijing–Tianjin–Hebei region during APEC than
in late October. We further demonstrate that high PM<sub>2.5</sub> events in Beijing during this period can be occasionally contributed
by natural mineral dust, but more events show large sensitivities
to inorganic aerosol sources, particularly emissions of ammonia (NH<sub>3</sub>) and nitrogen oxides (NO<sub><i>x</i></sub>) reflecting
strong formation of aerosol nitrate in the fall season.