Haze pollution is
an integrated result of emissions, chemical reactions and regional transport
under unfavorable weather conditions. Numerical simulation has the potential to
strengthen our knowledge on the underlying mechanisms of haze formation. As a
result, policymakers might benefit and efficient control strategies should
emerge.
Illustration
of how unfavorable weather conditions and emissions result in haze pollution in
urban areas.
Dr. Nan WANG, from
the Institute of Tropical and Marine Meteorology, China Meteorological
Administration, and Dr. Zhenhao Ling,
from Sun Yat-sen University, collected historical data on haze episodes and classified
them according to the associated synoptic weather systems. With the aid of
numerical simulation, they summarized the characteristics of source region
contributions to fine-particle pollution under the most frequent unfavorable
weather systems in Guangzhou—a typical city of China’s important Pearl River
Delta region. They suggested that source region contributions showed
significant differences when controlled by different synoptic systems.
“Our statistical
results show that SP [‘sea high pressure’] and FC [‘foreside of a cold front’] are
the most frequent unfavorable weather systems in the PRD [Pearl River Delta
region]. Usually, Siberian cold high pressure, the predecessor of SP, moves
easterly to the sea, forming a weaker but warmer SP. After that, SP extends to
southern China and dominates the PRD. A stationary atmosphere can be found and local
emissions are the main cause of haze events. However, an FC-affected event means
that the convergence of warm and cold air flow occurring to the northwest of
the PRD will result in northerly wind prevailing over the PRD. Pollutants from
upwind areas become the main factor. Therefore, policymakers can develop more
efficient control plans by incorporating weather system analysis when haze
events occur.”
Dr. Zhenhao LING further
explains that meteorological conditions and emissions are the two main factors
causing haze pollution, and that chemical transport models may help us to
quantify their relative impacts and thus provide scientific guidance for government
decisions around emission control measures.
Reference
Wang,
N, and Coauthors, 2018: Source contributions to fine particulate matter
pollution under unfavorable weather conditions in Guangzhou City, China. Adv. Atmos. Sci., 35(9), https://link.springer.com/article/10.1007/s00376-018-7212-9 .
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