Bian, HS; Chin, MA; Kawa, SR; Yu, HB; Diehl, T; Kucsera, T (2010). Multiscale carbon monoxide and aerosol correlations from satellite measurements and the GOCART model: Implication for emissions and atmospheric evolution. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 115, D07302.
Regional correlations of CO and aerosol on different time scales provide information on their sources, lifetimes, and transport pathways. We examine regional and global column CO and fine-mode aerosol optical depth (AODf) correlations from daily to seasonal scales using 7 years (2000-2006) of satellite observations from the Measurement of Pollution in the Troposphere and the Moderate Resolution Imaging Spectroradiometer and model simulations from the Goddard Chemistry Aerosol Radiative Transport model. Our analyses indicate that, globally, column CO and AODf have similar spatial distributions due to their common source locations, although CO is more spatially dispersed because of its longer lifetime. However, temporal CO-AODf correlations differ substantially over different timescales and different regions. On daily to synoptic scales CO and AODf have a positive correlation over the industrial and biomass burning source regions owing to the covariance of emissions and coherent dynamic transport. No such correlation is seen in remote regions because of the diverging influence of mixing and chemical processes during longer-range transport. On the seasonal scale in the Northern Hemisphere, CO and AODf are out of phase by 2-4 months. This phase lag is caused by photochemical production of sulfate, which is the major component of fine-mode aerosol in the Northern Hemisphere, and photochemical destruction of CO in reaction with OH (both at maximum in the summer and at minimum in the winter), together with the seasonality of fine-mode dust, which peaks in the boreal spring season. In the Southern Hemisphere tropics and subtropics, however, CO and AODf are generally in-phase because the variability is dominated by direct release from biomass burning emissions.