We used the nested grid version of the global three-dimensional Goddard EarthObserving System chemical transport model (GEOS-Chem) to examine theinterannual variations (IAVs) of aerosols over heavily polluted regions inChina for years 2004–2012. The role of variations in meteorologicalparameters was quantified by a simulation with fixed anthropogenic emissionsat year 2006 levels and changes in meteorological parameters over 2004–2012.Simulated PM (particles with a diameter of 2.5 μm or less)aerosol concentrations exhibited large IAVs in North China (NC;32–42° N, 110–120° E), with regionally averaged absolutepercent departure from the mean (APDM) values of 17, 14, 14, and 11% inDecember-January-February (DJF), March-April-May (MAM),June-July-August (JJA), and September-October-November (SON), respectively.Over South China (SC; 22–32° N, 110–120° E), the IAVs inPM were found to be the largest in JJA, with the regional mean APDMvalues of 14% in JJA and of about 9% in other seasons.The concentrations of PM over the Sichuan Basin (SCB; 27–33° N,102–110° E) were simulated to have the smallest IAVs among thepolluted regions examined in this work, with APDM values of 8–9%in all seasons. All aerosol species (sulfate, nitrate, ammonium, blackcarbon, and organic carbon) were simulated to have the largest IAVs over NCin DJF, corresponding to the large variations in meteorological parametersover NC in this season. Process analyses were performed to identify the keymeteorological parameters that determined the IAVs of different aerosolspecies in different regions. While the variations in temperature andspecific humidity, which influenced the gas-phase formation of sulfate,jointly determined the IAVs of sulfate over NC in both DJF and JJA, wind (orconvergence of wind) in DJF and precipitation in JJA were the dominantmeteorological factors to influence IAVs of sulfate over SC and the SCB. TheIAVs in temperature and specific humidity influenced gas-to-aerosolpartitioning, which were the major factors that led to the IAVs of nitrateaerosol in China. The IAVs in wind and precipitation were found to drive theIAVs of organic carbon aerosol. We also compared the IAVs of aerosolssimulated with variations in meteorological parameters alone with thosesimulated with variations in anthropogenic emissions alone; the variations inmeteorological fields were found to dominate the IAVs of aerosols in northernand southern China over 2004–2012. Considering that the IAVs inmeteorological fields are mainly associated with natural variability in theclimate system, the IAVs in aerosol concentrations driven by meteorologicalparameters have important implications for the effectiveness of short-termair quality control strategies in China.
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