This study revisits the Southern Hemisphere's only major sudden stratospheric warming in September 2002, marked by an unprecedented polar vortex split. In addition to upward-propagating planetary wave 2 (PW2), westward PW2 generated in-situ by barotropic–baroclinic instability, contributed to the vortex split. Unstable PW2 growth resulted from nonlinear wave-wave interactions and over-reflection. Vortex destabilization occurred as the anomalously poleward-shifted vortex reversed to easterlies.

We developed a new method to detect turbulence in the atmosphere using global high-resolution balloon measurements of temperature and wind. Unlike earlier methods, ours can detect turbulence not only in unstable air but also in stable layers with strong wind changes. This approach better matches aircraft turbulence reports and reveals global patterns, such as seasonal shifts linked to jet streams and convection, helping improve flight safety and our understanding of extreme weather.

The January 2021 sudden stratospheric warming was preceded by unusual double westerly jets with polar stratospheric and subtropical mesospheric cores. This wind structure promotes anomalous dissipation of tropospheric planetary waves between the two maxima, leading to unusually strong shear instability. Shear instability generates the westward-propagating planetary waves with zonal wavenumber 2 in situ, thereby splitting the polar vortex just before the onset.

The cube root of the energy dissipation rate (EDR), as a standard reporting metric of atmospheric turbulence, is estimated using 1 Hz commercial quick access recorder data from Korean-based national air carriers with two different types of aircraft. Various EDRs are estimated using zonal, meridional, and derived vertical wind components and the derived equivalent vertical gust. Characteristics of the observed EDR estimates using 1 Hz flight data are examined to observe strong turbulence cases.