Elucidating the Key Processes Modulating the Surface Ozone Concentration over Northern China

Abstract:

While the process analysis has been widely used to track the physical and chemical processes affecting the ozone concentration in regional chemical models, we make a step forward to quantify the relationship between the chemical processes and surface ozone concentration. Based on the episodic events over North China Plain during June 2017, we first found that the photochemical reactions within the planetary boundary layer (PBL) almost becomes the only source triggering the accumulation of surface ozone concentration, while the other processes mainly act as the sink. The unique feature stimulated that a possible linear relationship might exist between chemical reactions and surface ozone. By compositing the high and low ozone periods, we successfully constructed a linear regression and found that maximum daily 8-hr ozone (MDA8) ozone concentration was highly correlated with the chemical reactions in PBL. A further examination reveals that MDA8 surface ozone concentration was also tightly linked to the ozone hourly change rate during the day time. The close connection between surface MDA8 and surface ozone change rate or chemical reactions in PBL implies a possible dynamical emission control strategy might be carried out to prohibit the fast accumulation of ozone in particular of a focus on specific episodic events.