The separated polar winter stratopause: a gravity wave driven climatological feature

Abstract

An examination of satellite-derived temperatures reveals that the winter polar stratopause is usually elevated and warmer than the adjacent midlatitude stratopause. This "separated stratopause' occurs in both hemispheres, but is more pronounced and persistent in the southern winter. It descends with time towards spring and exhibits week to week variability. Observational diagnostics and results from a two-dimensional (2-D) model suggest that gravity wave driving can account for this separated polar stratopause by driving a meridional circulation, with downwelling over the winter pole. Model results suggest that descent of the temperature maximum with time is probably caused by wave-mean flow interaction. -from Authors