Evidence of localized H₂O increases and O₃ recovery in the Antarctic lower stratospheric vortex: MLS observations and BDC variability during late winter to spring

Hian, Jackson Wui Chang and Chee, Fuei Pien and Justin Sentian and Raul R. Cordero and Chel, Maggie Gee Ooi and Yong, Jie Wong (2025) Evidence of localized H₂O increases and O₃ recovery in the Antarctic lower stratospheric vortex: MLS observations and BDC variability during late winter to spring. Atmospheric Research, 328 (108428). pp. 1-15. ISSN 0169-8095

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Abstract

We examined the interannual variability in ozone (O3) and water vapor (H2O) in the lower stratospheric vortex over Antarctica using 19 years of measurements (2004–2022) from the Aura Microwave Limb Sounder (MLS). We focused on the period of the southern hemisphere winter (11–20 September), late winter (21–30 September), and spring (1–10 October) because O3 and H2O dynamics show the most variation during these times. We used a low-pass filter to focus on variations lasting 10 days or longer. The Mann Kendall test and regression analysis were employed to identify linear or non-linear trends. Our findings showed that the vortex-average O3 increased at 0.01 ppm yr- 1. In contrast, the vortex-averaged H₂O showed no significant trend, although localized increases in H₂O were significantly obvious across all latitudes. In addition to the well-known effects of the Montreal Protocol, we hypothesize that the localized increase in H₂O is driven by the redistribution of water vapor due to strengthened Brewer-Dobson circulation (BDC) dynamics, characterized by enhanced horizontal transport, which, however, is insufficient to induce significant changes in vortex-averaged H₂O. The observed out-of-phase trend between the vertical and horizontal branches of the BDC serves to validate our BDC speed calculation. These results highlight the complex interplay between dynamics and chemistry in the polar stratosphere, emphasizing that while O₃ recovery continues, localized changes in H₂O do not yet significantly impact the vortex-averaged H₂O levels. Our study provides new insights and observational evidence into the role of BDC dynamics and stratospheric ozone recovery, underscoring the importance of both chemical and dynamic processes in shaping the future evolution of the stratospheric ozone layer.

Item Type:	Article
Keyword:	Antarctica ozone, Ozone dynamics, Polar stratosphere, Brewer-Dobson circulation, BDC, Microwave limb sounder, MLS, Vortex-averaged O3 and H2O
Subjects:	Q Science > QC Physics > QC1-999 Physics > QC851-999 Meteorology. Climatology Including the earth's atmosphere > QC980-999 Climatology and weather
Department:	CENTRE > Preparation Centre for Science and Technology
Depositing User:	DG MASNIAH AHMAD -
Date Deposited:	02 Sep 2025 15:37
Last Modified:	02 Sep 2025 15:37
URI:	https://eprints.ums.edu.my/id/eprint/45086

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