Satellite-based estimates of high-resolution CO concentrations at ground level in the Yangtze River Economic Belt of China

This study proposed a method to downscale ground-level CO concentrations from satellite observations. Taking the Yangtze River Economic Belt of China as the study area, ground-level CO concentrations (0.25 degrees x 0.25 degrees) were first estimated from the troposphere (MOPITT) CO columns and atmospheric CO profiles simulated by the chemical transport model CAM-CHEM; then the resulting data was downscaled to 1 x 1 km2 based on an algorithm of multiscale geo-weighted regression (MGWR) model with the auxiliary factors. The estimated groundlevel CO concentrations were in good agreement with the observations at ground-based sites (RMSE = 0.25 mg/ m3, PRE = 19%). In the Yangtze River Economic Belt, monthly ground-level CO concentrations showed obvious temporal and spatial variations, ranging from 0.30 to 0.81 mg/m3 and an average of 0.49 mg/m3; high CO values occurred in winter, while low in summer; hotspots of CO concentrations were concentrated in the northern Yangtze River Delta and the urban areas.