Comparing Stratospheric Influence on Tropospheric Ozone Across CCMI Models

We explore the relationship between the stratospheric circulation and ozone variability in both the stratosphere and troposphere in the Whole Atmosphere Chemistry-Climate Model (WACCM). Our analysis strives to untangle the roles of the El Nino/Southern Oscillation (ENSO) and the Quasi-Biennial Oscillation (QBO) in driving circulation changes and examine small but important differences in the response of the residual vertical velocity versus the Brewer-Dobson Circulation (BDC) transport velocity (as measured by the water vapor tape recorder) to these signals. We further explore the relationships between circulation variability and ozone changes throughout the stratosphere and troposphere and compare these to observations from the Aura Microwave Limb Sounder and Tropospheric Emission Spectrometer. Building on our understanding derived from the WACCM analysis, we examine the consistency of these relationships within the suite of CCMI models. As tape recorder speeds vary from model to model, so do the midlatitude tropospheric ozone amounts. By quantifying these differences in relation to ENSO and QBO (and how “in sync” they are with the seasonal cycle), we are able to evaluate the robustness of these signals. Through this approach, we hope to diagnose models that do not accurately represent the variability of the BDC and its impact on ozone transport.