How Complete Is Our Knowledge of Tropospheric Ozone? (at Least as it is Currently Incorporated into Chemistry-Climate Models)

Abstract:

Chemistry-climate models (CCMs) are ambitious efforts to synthesize virtually our entire knowledge of atmospheric chemistry. They provide calculations of atmospheric composition through the depth of the atmosphere over the entire globe. The models can simulate not only present-day conditions, but also provide reproductions of the past and predictions of the future. Thus, these models can generally address all questions relating to the concentrations of atmospheric species and the variability of those concentrations in location and time. However, these models are so complex that it is difficult to judge the confidence to place on the answers provided. The goal of this talk is to critically and quantitatively compare measured aspects of the tropospheric O₃ distribution with those calculated by three CCMs. The focus will be on the seasonal cycles and long-term concentration changes observed at a variety of approximately baseline sites at northern mid-latitudes and in the southern hemisphere. Some important model-measurement disagreements will be noted. The ultimate goal of this work is to develop robust metrics for comparing model simulations to observations that will allow model-measurement comparisons to be rapidly performed in a standard, quantitative manner that can both effectively inform model improvement and advance our knowledge of tropospheric ozone.