Comparison study of the polar cold air mass between Northern and Southern Hemispheric winters based on a zonal‐mean two‐box model

摘要

The characteristics of the polar cold air mass (PCAM) below a threshold potential temperature θ _(T) are quantitatively compared between two hemispheric winters and analyzed with a zonal‐mean two‐box model. This model estimates a residence time in a genesis box, a life time in a loss box, and PCAM flux between them. The hemispheric total PCAM amount below θ _(T) =280?K in the Northern Hemispheric winter is approximately 40% greater than that in the Southern Hemispheric winter. This difference is attributed to the residence time enhanced due to the land–sea distribution and mountain barriers, while the PCAM flux is almost equivalent between the two winters.