Nanjing University reveals the cross-regional spread mechanism of smog
【Technological frontier】
Atmospheric composite pollution characterized by PM2.5 is an important environmental challenge facing the eastern part of my country. During the occurrence of heavy pollution, understanding the cross-border transmission of pollution and local contributions is the key to the prevention and control of air pollution. It is particularly important for science to take appropriate measures to achieve "precise haze control". Recently, the latest research results of the research team of Ding Aijun and Fu Congbin, School of Atmospheric Sciences, Nanjing University, and Collaborative Innovation Center for Climate Change of Jiangsu Province have revealed that the heavy smog pollution in Beijing, Tianjin, Hebei, and the Yangtze River Delta has enhanced cross-boundary transmission through interaction in autumn and winter At the same time, it puts forward new ideas for mitigating such regional interactions to achieve scientific haze control. The relevant results of this research have recently been published in "Nature-Earth Science" under the title "Interaction of Aerosols and Boundary Layers to Enhance Air Pollution Transmission across my country".
Ding Aijun, the dean of the School of Atmospheric Sciences at Nanjing University, said that since the implementation of the “Clean Air Action Plan” (“National Ten Articles”) in 2013, the air quality in eastern China has improved significantly, but sometimes even in many cities with strict emission reductions , Heavy haze pollution incidents still occur from time to time. Taking the end of 2017 to the beginning of 2018 as an example, a large-scale haze event occurred in North China and East China. The study was based on multiple observations and numerical model simulations and found that the pollution event on the surface appears to be affected by the long-distance transmission of regional pollution in North China. In fact, in the early period of North China, the heavy haze increased the static weather The conditions are significantly affected by specific pollution emissions in the Yangtze River Delta and other places.
The study found that regional emissions of black carbon aerosols with strong solar radiation absorption characteristics can be quickly transported to the upper boundary layer of Beijing-Tianjin-Hebei, and the meteorological conditions in the Beijing-Tianjin-Hebei region can be changed through the aerosol-boundary layer interaction. , Aggravating the formation of static weather (the "dome effect" of the upper layer of the boundary layer warming and the lower layer of cooling); at the same time, the increase of relative humidity in the boundary layer caused by the cooling temperature significantly promotes the formation of secondary particles, which intensifies the pollution in North China; Under the influence of the subsequent cold front, the regional heavy haze went south and affected the entire eastern region including the Yangtze River Delta. The study found that since 2013, 18 similar regional-scale heavy pollution times can be explained by this mechanism. For the Yangtze River Delta, the same emission reduction intensity, as long as the emission reduction time point is two days ahead of the normal forecast of heavy haze, not only can reduce pollution in North China, but also help to carry out the heavy pollution process of long-distance transmission later Peak cut.
The study found for the first time that on a spatial scale of thousands of kilometers, the vertical air pollution-atmospheric boundary layer feedback process can interact with the large-scale weather process and further enhance pollution transmission between regions. This study further proved the complexity and non-linearity of the cause of atmospheric composite pollution in my country's unique environmental conditions. On the one hand, the knowledge based on surface observation alone is not enough to fully understand the causes of atmospheric composite pollution, nor can it fully understand the causes of atmospheric composite pollution; on the other hand, the regional source analysis based on traditional numerical models is not enough to accurately assess the transboundary pollution transmission. In the future, combined atmospheric pollution will need to further strengthen the integrated monitoring of the sky and the ground, and also need to further optimize the physical and chemical process description of the computer model to improve the timeliness of air quality forecasting. Only in this way can "scientific haze control and precise haze control" be truly achieved.
(Reporter Su Yan)