Zonally and Seasonally Resolved Ozone Response to the MJO and ENSO in Aura Satellite Measurements of the Upper Troposphere Lower Stratosphere

Atmospheric and oceanic oscillations of multiple timescales have a significant impact on the circulation and composition of the upper troposphere and lower stratosphere (UTLS). Previous studies showed that variability of the tropical UTLS is dominated by the Madden Julian Oscillation (MJO) and El Niño Southern Oscillation (ENSO) on subseasonal and interannual timescales respectively. However, many observational studies of ozone variability in the tropics were limited by temporal and spatial coverage of the datasets. Observations from the Microwave Limb Sounder (MLS, version 4) on Aura satellite now provide long and continuous coverage (over 14 years) of high-quality data, suitable for the investigation of zonal and height variations as well as for performing analysis for boreal winter (Nov.-Jan.) and summer (June - Sept.) seasons separately. In this study, we evaluate and explain the seasonal and zonal differences in the UTLS ozone, temperature, and circulation anomalies associated with the MJO and ENSO using ozone and temperature from MLS and meteorological fields from the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) reanalysis. Our analysis of MLS ozone anomalies, associated with both ENSO and MJO, shows strong seasonal and zonal variations. Observed differences in ozone interannual and intraseasonal variability are strongly coherent with changes in the atmospheric circulation. Furthermore, we use the analysis of MLS observations to evaluate and validate the ENSO and MJO-related physical and dynamical processes in a hierarchy of models.