Aerosol–radiation feedback deteriorates the wintertime haze in the North China Plain
<p>Atmospheric aerosols scatter or absorb a fraction of the incoming solar radiation to cool or warm the atmosphere, decreasing surface temperature and altering atmospheric stability to further affect the dispersion of air pollutants in the planetary boundary layer (PBL). In the present study,...
Main Authors: | , , , , , , , , , , , , , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2019-07-01
|
Series: | Atmospheric Chemistry and Physics |
Online Access: | https://www.atmos-chem-phys.net/19/8703/2019/acp-19-8703-2019.pdf |
Summary: | <p>Atmospheric aerosols scatter or absorb a fraction of the
incoming solar radiation to cool or warm the atmosphere, decreasing surface
temperature and altering atmospheric stability to further affect the
dispersion of air pollutants in the planetary boundary layer (PBL). In the
present study, simulations during a persistent and heavy haze pollution
episode from 5 December 2015 to 4 January 2016 in the North China Plain
(NCP) were performed using the Weather Research and
Forecasting model with Chemistry (WRF-Chem) to comprehensively quantify
contributions of aerosol shortwave radiative feedback (ARF) to near-surface
(around 15 m above the ground surface) PM<span class="inline-formula"><sub>2.5</sub></span> mass concentrations. The
WRF-Chem model generally performs well in simulating the temporal variations
and spatial distributions of air pollutants concentrations compared to
observations at ambient monitoring sites in the NCP, and the simulated
diurnal variations of aerosol species are also consistent with the
measurements in Beijing. Additionally, the model simulates the aerosol
radiative properties, the downward shortwave flux, and the PBL height
against observations in the NCP well. During the episode, ARF deteriorates the
haze pollution, increasing the near-surface PM<span class="inline-formula"><sub>2.5</sub></span> concentrations in
the NCP by 10.2 <span class="inline-formula">µ</span>g m<span class="inline-formula"><sup>−3</sup></span> or with a contribution of 7.8 % on
average. Sensitivity studies have revealed that high loadings of PM<span class="inline-formula"><sub>2.5</sub></span>
attenuate the incoming solar radiation reaching the surface to cool the
low-level atmosphere, suppressing the development of the PBL, decreasing the surface
wind speed, further hindering the PM<span class="inline-formula"><sub>2.5</sub></span> dispersion, and consequently
exacerbating the haze pollution in the NCP. Furthermore, when the
near-surface PM<span class="inline-formula"><sub>2.5</sub></span> mass concentration increases from around 50 to
several hundred <span class="inline-formula">µ</span>g m<span class="inline-formula"><sup>−3</sup></span>, ARF contributes to the near-surface
PM<span class="inline-formula"><sub>2.5</sub></span> by more than 20 % during daytime in the NCP, substantially
aggravating the heavy haze formation. However, when the near-surface
PM<span class="inline-formula"><sub>2.5</sub></span> concentration is less than around 50 <span class="inline-formula">µ</span>g m<span class="inline-formula"><sup>−3</sup></span>, ARF
generally reduces the near-surface PM<span class="inline-formula"><sub>2.5</sub></span> concentration due to the
consequent perturbation of atmospheric dynamic fields.</p> |
---|---|
ISSN: | 1680-7316 1680-7324 |