Abstract
We present combined Mie lidar, ozone lidar and wide-range particle spectrometer observations that were carried out in Beijing, north China during two periods—one haze period before the Asia-Pacific Economic Cooperation (APEC) meeting and one moderate pollution period during the meeting in 2014. High extinction coefficient, moderate ozone concentration and variable particle number concentration were obtained throughout the first haze observation period. The mean extinction coefficients in the two pollution periods were 0.52 km-1 and 0.23 km -1 , respectively, at 532 nm. The ozone concentration during the first haze phase was more various with higher average value of 49 ppb compared to that in the second pollution observations (32 ppb). The comparison of aerosols and ozone in different heights indicate different pollution sources and complicated ozone process of generation and disappearance. The four-day back trajectories from a HYSPLIT model indicate that the air masses in the lower boundary layer were advected from the densely populated south regions of China and the long pollution transportation passing through northern China.
Highlights
Aerosol particles can absorb and scatter radiation efficiently, thereby affecting the balance of the atmospheric radiation system of the Earth [1,2].And many studies indicated that both direct emitted particles from human activities and secondary aerosols lead to significant reduction in visibility and the increase of haze occurrence [3,4,5]
Because the average value of the RH at ground level did not exceed 85% to reach saturation, we conclude that the two pollution periods: one haze pollution period from October 28 to October 30 and one moderate pollution period from November 4 to November 5
The results show the retrieval of aerosol extinction and ozone based on Mie lidar and ozone DIAL lidar measurements
Summary
Aerosol particles can absorb and scatter radiation efficiently, thereby affecting the balance of the atmospheric radiation system of the Earth [1,2].And many studies indicated that both direct emitted particles from human activities and secondary aerosols lead to significant reduction in visibility and the increase of haze occurrence [3,4,5]. Much of the present tropospheric ozone burden is a consequence of anthropogenic emissions of ozone precursors resulting in widespread increases in ozone concentrations [7,8]. It is important get understanding of aerosol properties and ozone concentration variation. Tesche et al (2007) presented lidar observations of particle optical properties (backscatter coefficient, extinction coefficient and lidar ratio) in Beijing in North China. Knowledge on the combined optical properties of aerosol particles and ozone over northern China is sparse, at least in the vertical scale. Experimental data in northern are strongly needed to assess the role of aerosols in future scenarios of global change and the impact on human health
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