Search for: All records

Abstract. Stratospheric circulation is a critical part of the Arctic ozone cycle.Sudden stratospheric warming events (SSWs) manifest the strongest alterationof stratospheric dynamics. During SSWs, changes in planetary wavepropagation vigorously influence zonal mean zonal wind, temperature, andtracer concentrations in the stratosphere over the high latitudes. In thisstudy, we examine six persistent major SSWs from 2004 to 2020 using theModern-Era Retrospective analysis for Research and Applications, Version 2(MERRA-2). Using the unique density of observations around the Greenlandsector at high latitudes, we perform comprehensive comparisons of high-latitude observations with the MERRA-2 ozone dataset during the six majorSSWs. Our results show that MERRA-2 captures the high variability of mid-stratospheric ozone fluctuations during SSWs over high latitudes. However,larger uncertainties are observed in the lower stratosphere and troposphere.The zonally averaged stratospheric ozone shows a dramatic increase of9 %–29 % in total column ozone (TCO) near the time of each SSW, which lastsup to 2 months. This study shows that the average shape of the Arcticpolar vortex before SSWs influences the geographical extent, timing, andmagnitude of ozone changes. The SSWs exhibit a more significant impact onozone over high northern latitudes when the average polar vortex is mostlyelongated as seen in 2009 and 2018 compared to the events in which the polarvortex is displaced towards Europe. Strong correlation (R2=90  %) isobserved between the magnitude of change in average equivalent potentialvorticity before and after SSWs and the associated averaged total columnozone changes over high latitudes. This paper investigates the differentterms of the ozone continuity equation using MERRA-2 circulation, whichemphasizes the key role of vertical advection in mid-stratospheric ozoneduring the SSWs and the magnified vertical advection in elongated vortexshape as seen in 2009 and 2018.