Figure 4
From: “APEC Blue”: Secondary Aerosol Reductions from Emission Controls in Beijing
A conceptual framework on primary and secondary aerosol evolution.
The 72 hr evolution of mass concentrations and mass fractions of primary and secondary aerosol without emission controls before APEC (A1 and A2) and with the emission controls during APEC (B1 and B2). The evolution of primary species starts from noontime with te lowest concentrations in a day. SIABG, SOABG and BCBG refer to the regional background concentrations of secondary inorganic aerosol, secondary organic aerosol and black carbon. SIAR, SOAR and BCR are the concentrations from regional transport which are calculated based on the accumulation rates during the episodes of 16–17 October and 7–8 November, respectively. BCL and POAL refer to the local sources that were calculated from the diurnal profiles of POA (HOA, COA and BBOA) and BC (regional background and transport were excluded) before and during APEC. A2 and B2 show the evolution of the mass fraction of aerosol species from different sources.
