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Study Reveals Long-term Characteristics of Atmospheric Mixing Layer Height over Beijing

Aug 07, 2020

A research team led by Prof. LI Zhengqiang from the Aerospace Information Research Institute (AIR) of the Chinese Academy of Sciences has revealed long-term characteristics of the atmospheric mixing layer height (MLH) over Beijing by laser radar (lidar).

The study was published in Atmospheric Chemistry and Physics on July 27.

The atmospheric MLH determines the space in which pollutants diffuse and it is conducive to estimate pollutant concentration near the surface.

Commonly, numerical simulations, ground remote sensing or meteorological radiosondes are used to obtain short-term characteristics of the MLH in Beijing during heavy pollution events, while continuous long-term observations of the MLH are relatively lacking.

In this study, the research team used lidar to observe daily variation of atmospheric MLH and obtained climatological characteristics of the diurnal cycle of MLH. 

"Compared with radiosondes results, the lidar results showed good performance in calculating the height of the convective boundary layer during daytime and the height of the residual layer at nighttime, and also revealed potential of obtaining the height of the stable boundary layer at night," said Prof. LI.

The study also showed seasonal characteristics of the maximum diurnal variation of MLH in Beijing, indicating that it is lower in winter and autumn and higher in spring and summer.

From 2014 to 2018, the annual average of the daily maximum value of the mixing layer height increased year by year, with a total increase of 0.338 km, of which the largest increase appeared in 2016.

"The increment in the height of the mixing layer is partly due to the improvement of air quality in Beijing," said Prof. LI.

The lidar observation-based dataset of the long-term diurnal change of MLH over Beijing urban area could provide valuable data reference for studying the near-surface air pollution of the region by using atmospheric model.

The research was supported by the National Natural Science Foundation of China.  

Contact

LU Yiqun

Aerospace Information Research Institute

E-mail:

Determination and climatology of the diurnal cycle of the atmospheric mixing layer height over Beijing 2013–2018: lidar measurements and implications for air pollution

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