Modeling of spatial and temporal variations of ozone-NOx-VOC sensitivity based on photochemical indicators in China
2022
Du, Xiaohui | Tang, Wei | Cheng, Miaomiao | Zhang, Zhongzhi | Li, Yang | Li, Yu | Meng, Fan
Comprehensive air quality model with extensions (CAMx)-decoupled direct method (DDM) was used to simulate ozone-NOₓ-VOCs sensitivity of for May–November in 2016–2018 in China. Based on the relationship between the simulated ozone (O₃) sensitivity values and the ratio of formaldehyde (HCHO) to NO₂ (FNR) and the ratio of production rate of hydrogen peroxide (H₂O₂) to production rate of nitric acid (HNO₃) (PH2O2/PHNO3), the localized range of FNR and PH2O2/PHNO3 thresholds in different regions in China were obtained. The overall simulated FNR values are about 1.640–2.520, and PH2O2/PHNO3 values are about 0.540–0.830 for the transition regime. Model simulated O₃ sensitivities or region specific FNR or PH2O2/PHNO3 thresholds should be applied to ensure the accurate local O₃ sensitivity regimes. Using the tropospheric column FNR values from ozone monitoring instrument (OMI) satellite data as an indicator with the simulated threshold values, the spatial distributions of O₃ formation regimes in China are determined. The O₃ sensitivity regimes from eastern to central China are gradually from VOC-limited, transition to NOₓ-limited spatially, and moving toward to transition or NOₓ-limited regime from 2005 to 2019 temporally.
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