PMC

Global wind patterns overlaying the distributions of the Southern Hemisphere (VI), Northern Hemisphere (VII), and tropical (II) clades (see ). Red arrows: Trade Winds; blue arrows: Westerlies; grey arrows: Polar Easterlies.

Scatterplot of all WACCMX+DART versus Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) zonal mean zonal wind data presented in Figure . (a) Days that satisfy minor and major sudden stratospheric warming (SSW) conditions are indicated with yellow and red dots, respectively. (b) as panel (a) but red dots indicate easterlies at 0.6 hPa instead of at 10 hPa.

Timeseries of WACCMX+DART (black with diamonds) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) (gray) 0.001 hPa daily average zonal mean zonal winds poleward of 40°N for each January‐March northern SABER yaw from 2006 to 2019. Days that satisfy minor and major sudden stratospheric warming conditions are indicated with yellow and red dots, respectively. Days with easterlies near the stratopause (0.6 hPa) are indicated with blue diamonds.

Southern Ocean circulation and circumpolar oceanic fronts. (a) The Antarctic Circumpolar Current (ACC) marked by blue arrows and main oceanic fronts from north to south are represented by the sub-Tropical Front (STF), Subantarctic Front (SAF), the Polar Front (PF), and the Southern ACC Front (SACC). Figure adapted from ref.. (b) Simplified schematic representation of the present-day Southern Ocean overturning circulation^,. Ekman transport (ET) resulting from the Antarctic Coastal Current flowing counter-clockwise around Antarctica under the influence of the Polar easterlies causes waters to move towards Antarctica, while a northbound Ekman transport resulting from an eastbound ACC drives the waters away from Antarctica. It creates an area of divergence called the Antarctic Divergence Zone, where the Circumpolar Deep Water (CDW) upwells to the surface south of the Polar Front (PF). Northward advection of nutrient-rich upwelled water takes place by Ekman transport and references therein. Its subsequent subduction to intermediate depths forms the Antarctic Intermediate Water (AAIW). Part of the upwelled waters moves southwards forming the Antarctic Bottom Water (AABW). During the northward advection, some part of the Antarctic surface water mixes with subtropical surface water to form Subantarctic Mode Water (SAMW).