A study on the characteristics of Ozone Weekend Effect and reaction sensitivity in Chengdu

Abstract

Abstract This study improved the computation theory “Ozone Weekend Effect Method” (OWEM) and analyzed the 2016 observation data from the state-controlled ambient air quality monitoring sites in Chengdu using the OWEM theory. The improved OWEM theory is then applied to processing large sample data and making a judgment on photochemical reaction sensitivity in Chengdu. The result of applying the OWEM theory to Chengdu shows 1) that the VOCs-limited period, the NOx-limited period and the photochemical reaction steady-state period, Rt, accounted for 66.06%, 33.64% and 0.30%, respectively; 2) that on a seasonal basis, i.e. in the ozone photochemical reaction occurring in spring, summer, autumn and winter 2016 in Chengdu, the VOCs-limited period accounted for 59.40%, 72.49%, 63.85% and 68.49% of the 2016 observed data, respectively, and the NOx-limited period accounted for 39.70%, 27.51%, 36.15% and 31.19%respectively; 3) that in the VOCs-limited period and the NOx-limited period of August 2016, the month when the most serious ozone pollution of that year occurred in Chengdu, Rt accounted for 70.0% and 30.0%, respectively, and that there was no photochemical reaction steady-state zone period that month; 4) and that through estimation, it is suggested that as for the ozone pollution control of Chengdu, the ratio of VOCs emission reduction to NOx emission reduction should be around 3:1.