Collaborative Observation of Vertical Structures of Ozone and Aerosol in a Dust Episode Based on Lidar

The cooperative observation of atmospheric ozone and aerosol is realized by using the self-developed four-wavelength solid-state lidar system, which is also the first three-dimensional observation application of the system in China. Based on the radar system, the spatial vertical distribution characteristics of pollutants before, during and after a dust episodein Mid-April 2021 were studied. We found that the vertical distribution of ozone was mainly concentrated within 1. 5 km from the ground, and the ozone concentration before the dust was significantly higher than during and after dust. The vertical distribution of aerosol could reach the height of 2. 5 km before and in the dust. Due to the sudden entry of dust, the local extinction coefficient will increase abruptly by more than 2. 5 km(-1). After the passage of sand dust, the aerosol was mainly suppressed within 500 m near the ground. Through the continuous observations and the vertical-profile analysis of lidar, it is found that before the dust, a region of low ozone concentration with a minimum concentration of 13 mu g center dot m(-3) near the height of 300 m around 7 a. m. was displayed, which is about 1/4 of the nearby region. This low ozone region may be caused by the "titration effect" before sunrise in a stable atmospheric environment. However, the sudden input of dust not only eliminated the stable "titration effect" but also erasesd the daily variation of ozone by reducing the peak-to-valley value of ozone concentration on the ground to 55 mu g center dot m(-3), which was 0. 44 and 0. 46 times that before and after dust respectively. Meanwhile, the input of dust, reduced the proportion of fine particle mass concentration to less than 20% and transported more primary pollutants from upstream, further inhibiting the generation and transformation of ozone.