09 Nov 2022
09 Nov 2022
Status: this preprint is currently under review for the journal ACP.

The Holton-Tan mechanism under stratospheric aerosol intervention

Khalil Karami1, Rolando Garcia2, Christoph Jacobi1, Jadwiga H. Richter2, and Simone Tilmes2 Khalil Karami et al.
  • 1Institute for Meteorology, Leipzig University, Leipzig, Germany
  • 2National Center for Atmospheric Research, Boulder, CO, USA

Abstract. The teleconnection between the Quasi-Biennial Oscillation (QBO) and the Arctic stratospheric polar vortex, or the Holton-Tan (HT) relationship may change in a warmer climate or one with stratospheric aerosol intervention (SAI) as compared to present day climate (PDC). Our results from an Earth system model indicate that, under both global warming (based on RCP8.5 emission scenario) and SAI scenarios, the HT relationship weakens, although it is closer to PDC under SAI than under the RCP8.5 scenario. Such weakening of the HT relationship is more pronounced in early winter (Nov–Dec) compared to the mid-late winter period (Jan–Feb). While the high-latitude responses of temperature to the QBO anomalies are statistically significant under PDC, the responses are not statistically significant in the RCP8.5 and SAI scenarios. While the weakening of the HT relationship under RCP8.5 scenario is likely due to the weaker QBO wind amplitudes at the equator, another physical mechanism must be responsible for the weaker HT relationship under SAI scenario, since the amplitude of the QBO wind is comparable to the PDC. The strength of the polar vortex does not change under the RCP8.5 scenario compared to PDC, but it becomes stronger under SAI; we attribute the weakening of the HT relationship under SAI to such stronger polar vortex. In general, the changes in the HT relationship cannot be solely explained by changes to the critical line; the changes in the residual circulation (particularly due to the gravity wave contributions) are important too in explaining the changes in the HT relationship under RCP8.5 and SAI scenarios.

Khalil Karami et al.

Status: open (until 21 Dec 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-694', Anonymous Referee #1, 30 Nov 2022 reply
  • RC2: 'Comment on acp-2022-694', Anonymous Referee #2, 09 Dec 2022 reply

Khalil Karami et al.

Khalil Karami et al.


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Short summary
Alongside of mitigation and adaptation efforts, the stratospheric aerosol intervention (SAI) is increasingly considered a third pillar to combat dangerous climate change. We investigate the teleconnection between the quasi-biennial oscillation in the equatorial stratosphere and the Arctic stratospheric polar vortex under a warmer climate and a SAI scenario. We show that the Holton-Tan relationship weakens under both scenarios and discuss the physical mechanisms responsible for such changes.