Searching for the links between minor sudden stratospheric warmings in the Southern Hemisphere and polar vortex parameters

The relationship between minor sudden stratospheric warmings (SSWs) in the Southern Hemisphere (SH) and polar vortex parameters is poorly understood and requires new approaches. A key issue is identifying possible tropospheric and stratospheric precursors to minor SSWs in the SH. Such precursors could include unique blocking structures over the Southern Ocean and Rossby wave trains from the Indian Ocean-El Niño Dipole. Unlike the Northern Hemisphere, where such precursors are frequently studied, precursors in the Southern Hemisphere are less well known. They are likely related to oceanic or ocean-atmosphere transitions rather than topography. We analyzed the parameters of the polar vortex geometry during minor and major sudden stratospheric warmings in the Southern Hemisphere, as well as total ozone anomalies, to determine whether they could provide early warning signals for SSWs by identifying changes in vertical transport. We analyzed changes in vortex area based on potential vorticity at 60°S, which reveals vortex compression or expansion. We also explored the pathways of downward influence, specifically, whether the surface signal of minor SSWs in the Southern Hemisphere is predictable and whether it depends on the vortex's vertical structure, particularly its downward propagation velocity. Unlike the Northern Hemisphere, where an evident downward influence is observed, the signal in the SH is noisy, possibly due to factors such as vortex depth or the phase of the quasi-biennial oscillation (QBO). A search for the possible influence of the QBO on the occurrence and parameters of minor SSWs in the SH was conducted. The downward propagation rate of geopotential height anomalies and the SAM index response after a warming event were examined. Possible links between minor SSWs in the SH and predictable surface impacts were discussed. Unlike the Northern Hemisphere, where SSWs cause extremely low surface temperatures, a search was conducted for links between the SH minor SSW events and extremely high precipitation in Chile, New Zealand, and Australia.