Analyzing Ozone Variations and Uncertainties at High Latitudes During Sudden Stratospheric Warming Events Using MERRA-2

Concentrations of ozone in the Arctic atmosphere have an impact on global weather and climate. Thus, it is important to understand the variability of ozone and the processes associated with their variations. Large-scale atmospheric circulation has a strong influence on ozone concentrations in the Arctic. Sudden Stratospheric Warming events (SSWs) are dramatic alterations of the large-scale circulation. Using ground-based remote sensing data and ozonesondes, the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) datasets is evaluated in its ability to capture changes in ozone concentrations during SSWs. A uniquely dense network of observations at high latitudes, including three ozonesonde programs and five FTIR spectrometers from the high-latitude Network for the Detection of Atmospheric Composition Change (NDACC) sites, provide data for MERRA-2 evaluation. The results show a good agreement between MERRA-2 and independent observations in middle stratospheric layers during the SSWs. MERRA-2 is then used to investigate the impact of six SSWs from 2004 to 2020 on middle stratospheric ozone over the Arctic. This study shows that the position of the polar vortex before these events influences the variability of ozone. Ozone variability is more intensified and greater geographical extent exhibit positive ozone anomaly after SSWs with elongated polar vortex compared to SSWs with a displaced polar vortex. Investigation of different terms of trace continuity shows the dominant contribution of vertical advection on ozone variability during the SSWs.