Data include air pollutant surface concentrations simulated with the GEOS-Chem chemical transport model and measured at local and national monitoring networks in the Beijing-Tianjin-Hebei region.All data are in NetCDF format. Data files include:"gc-outputs-AW2016-base-emissions.nc" GEOS-Chem surface concentrations of PM2.5 components, CO, NO2, and SO2 over northern China averaged over October 2016 to March 2017 (AW2016) using unscaled bottom-up emissions. "gc-outputs-AW2016-scaled-NO-SO2-CO.nc" GEOS-Chem surface concentrations of PM2.5 components, CO, NO2, and SO2 over northern China averaged over October 2016 to March 2017 (AW2016) using bias-corrected emissions of NO, SO2 and CO."gc-outputs-AW2016-scaled-NO-SO2-CO-VOCs.nc" GEOS-Chem surface concentrations of PM2.5 components, CO, NO2, and SO2 over northern China averaged over October 2016 to March 2017 (AW2016) using bias-corrected emissions of NO, SO2, CO, and a test of the effect of 50% increase in anthropogenic NMVOCs emissions on CO concentrations."gc-outputs-AW2017-scaled-NO-SO2-CO-OC-BC.nc" GEOS-Chem surface concentrations of PM2.5 components, CO, NO2, and SO2 over northern China averaged over October 2017 to March 2018 (AW2017) using emissions for this time period obtained by scaling emissions for the previous year."gc-pm25-AW2017-with-MET-AW2016.nc" GEOS-Chem surface concentrations of PM2.5 over northern China using October 2017 - March 2018 (AW2017) emissions and October 2016 - March 2017 (AW2016) meteorology. The mean for Oct-Mar is given."gc-pm25-components-APHH-IAP.nc" Daily means of GEOS-Chem PM2.5 and components for the model grid coincident with the APHH field campaign in 2016 at the Institute of Atmospheric Physics urban site in Beijing."gc-pm25-components-APHH-Pinggu.nc" Daily means of GEOS-Chem PM2.5 and components for the model grid coincident with the APHH field campaign in 2016 at the Pinggu rural site in Beijing."surface-aq-regrid-to-geoschem.nc" Surface observations from local and national monitoring networks gridded to the GEOS-Chem model horizontal grid in northern China averaged from October 2016 to March 2017 (AW2016) and from October 2017 to March 2018 (AW2017). Also included are the relative changes from AW2016 to AW2017."met-condition-aw2016-aw2017.nc" Meteorology over northern China averaged over October 2016 to March 2017 (AW2016) and October 2017 to March 2018 (AW2017). Includes planetary boundary layer (PBL) height, surface temperature, relative humidity and 10-meter wind fields.All files are in NetCDF format.