Our goal is to understand the chemical composition of the atmosphere, its perturbation by human activity, and the implications for climate change and life on Earth. We address this goal through global modeling of atmospheric chemistry and climate, aircraft measurement campaigns, satellite data retrievals, and analyses of atmospheric observations.

PICTURE OF THE MONTH

P. S. Kim et al, Atmos. Chem. Phys., 13, 9321-9335, doi:10.5194/acp-13-9321-2013, 2013.

Patrick Kim et al 2014

Summary: We use the GEOS–Chem chemical transport model to interpret a new global data set of free tropospheric ozone-CO correlations that we produced from the OMI and AIRS satellite instruments as constraints on ozone sources. GEOS–Chem reproduces the general structure of the observed ozone-CO correlations and regression slopes, although there are some large regional discrepancies. We then examined the model sensitivity of dO3/dCO to different sources (combustion, biosphere, stratosphere, and lightning NOx), focusing on three illustrative regions of interest: (1) the North Atlantic in JJA; (2) the South Atlantic in DJF; and (3) the northeastern Pacific in SON. GEOS-Chem reproduces the observed ozone-CO relationship for (1) and (2) but fails for (3). We suggest that this reflects a model overestimate of lightning at northern midlatitudes combined with an underestimate of the East Asian CO source.

Caption:: Regional bar plots of ozone-CO statistics for (a) the western North Atlantic (30 - 40 N, 60 - 80 W) in JJA; (b) the South Atlantic (0 - 20 S, 30 W - 10 E) in DJF; and (c) the eastern Pacific (20 - 40 N, 120 - 160 W) in SON. From left to right, the bars show the ozone-CO regression slope (dO3/dCO) for OMI/AIRS, GEOS-Chem driven by GEOS-4, and GEOS-Chem driven by GEOS-5 in 2006; dO3/dCO for OMI/AIRS and GEOS-Chem driven by GEOS-5 in 2008; and d(delta O3)/dCO for simulations without combustion sources, biogenic sources, stratospheric influence, and lightning NOx emissions for 2008. Please see the manuscript for details!


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