Assessing The Ratios Of Formaldehyde And Glyoxal To No2 As Indicators Of O-3-Nox-Voc Sensitivity

Ozone (O-3) pollution has a negative effect on the public health and crop yields. Accurate diagnosis of O-3 production sensitivity and targeted reduction of O-3 precursors [i.e., nitrogen oxides (NQ) or volatile organic compounds (VOCs)] are effective for mitigating O-3 pollution. This study assesses the indicative roles of the surface formaldehyde-to-NO2 ratio (FNR) and glyoxal-to-NO2 ratio (GNR) on surface O-3-NOx-VOC sensitivity based on a meta-analysis consisting of multiple field observations and model simulations. Thresholds of the FNR and GNR are determined using the relationship between the relative change of the O-3 production rate and the two indicators, which are 0.55 +/- 0.16 and 1.0 +/- 0.3 for the FNR and 0.009 +/- 0.003 and 0.024 +/- 0.007 for the GNR. The sensitivity analysis indicated that the surface FNR is likely to be affected by formaldehyde primary sources under certain conditions, whereas the GNR might not be. As glyoxal measurements are becoming increasingly available, using the FNR and GNR together as O-3 sensitivity indicators has broad potential applications.