Modeling the variability of tropical ozone during sudden stratospheric warmings

Abstract This study investigates tropical total column ozone (TCO) variability during Sudden Stratospheric Warming (SSW) events, using data from the NCEP-NCAR Reanalysis 1 and NOAA/CIRES/DOE 20th Century Reanalysis (V3) datasets, supplemented by NOAA 10.7 cm solar radio flux data, spanning 1981–2015. Key parameters include TCO, air temperature, zonal and meridional winds, downward shortwave radiation flux (DSWRF), and upward longwave radiation flux (ULWRF). Methods included lagged composite analyses over a 91-day window (± 45 days from SSW onset) to compute TCO anomalies and raw variable averages, alongside mixed-effects modeling to capture fixed and random effects. Results show NH tropical TCO depletions of -2 to -3 DU at SSW onset (25°–30°N), recovery beginning after 20 days, while SH depletions range from − 4 to -10 DU (1988 minor event) to -2 to -4 DU (2002 major event), limited by sparse SH SSW events. Correlation analyses of Major SSW events reveal strong positive correlations between TCO and DSWRF (> 0.8) and temperature (0.4–0.8), with a delayed negative correlation for zonal wind (-0.8 at 25 days post-onset). Mixed-effects Model 1, with random intercepts and slopes (MSE = 3.4874), outperforms Model 2 (MSE = 12.423) via five-fold cross-validation, with temperature and DSWRF as key predictors. TCO underestimation in epoch 40 suggests unmodeled factors like stratospheric aerosols or planetary wave activity. These findings highlight the interplay of radiative, thermal, and dynamical processes during SSWs, with Model 1 showing promise for NH ozone forecasting.