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Abstract

Single scattering albedo (SSA), an important aerosol optical property, determines the effects of aerosols on actinic flux and ozone production. Similar to some measurement results in the United States and Europe, a strong positive correlation between SSA and aerosol optical depth (AOD) was also found in Beijing. Our results show that the enhancement of secondary aerosol formation induced by increased humidity and photochemical aging plays a major role in the positive correlation between SSA and AOD. Further analysis indicated that this positive correlation between SSA and AOD leads to a nonlinear relationship between photolysis frequencies and AOD. Omitting this positive correlation in radiative transfer models will lead to photolysis frequencies and ozone production rates being significantly overestimated under low AOD levels but significantly underestimated under high AOD levels. This result also implies that this positive correlation is conducive to the simultaneous occurrence of ozone and particulate matter pollution. We suggest that the positive correlation between SSA and AOD should be fully considered to accurately quantify the effect of aerosols on ozone production.