Analysis of tropospheric O3 and CO in continental outflow regions using IASI satellite observations and MOZART-4 model during the spring and the summer 2008
Résumé
Tropospheric O3 and CO are two important pollutants and play a major role in determining the oxidizing capacity of the troposphere. While observed correlations between O3 and CO from surface and aircraft measurements have been used in many studies to better understand the anthropogenic influence on O3, there have only been a few studies using global satellite data for this purpose. The correlation patterns provide also a valuable test for models to predict O3 photochemical production and global anthropogenic influence on O3. In this study, we propose to take advantage of the high spatio-temporal coverage of the Infrared Atmospheric Sounding Interferometer (IASI) instrument which provides a unique dataset for analyzing O3-CO correlations from simultaneous and vertically-resolved O3 and CO measurements. We examine global distributions of IASI O3-CO correlations in the lower, the middle and the upper troposphere during the spring (MAM) and the summer (JJA) 2008 to evaluate the continental influence on tropospheric ozone. Observed O3-CO correlations from IASI are also compared to the correlations simulated in the MOZART-4 global 3-D chemical transport model in order to test our understanding of anthropogenic influence on O3 and also to evaluate the photochemistry in the model. The feasibility for using the ratio dO3/dCO in estimating the O3 production is tested from IASI observations and compared to the MOZART-4 simulations. We further investigate the different sources of the correlations through analysis of CO and O3 from each CO and NOx emission sources tagged separately in the MOZART-4 simulations.