Seasonal transition in gravity wave activity during the springtime stratospheric vortex breakdown

Abstract

Profiles of temperature and wind measured by meteorological balloons are used to examine the changes in gravity wave activity at high latitudes during a final springtime breakdown of the Arctic stratospheric vortex. The measurements show that gravity wave potential energy densities in the lower stratosphere decreased dramatically as the cyclonic wintertime vortex gave way to the weak anticyclonic summertime circulation. The reduction in gravity wave activity after the vortex breakdown is attributed primarily to increased critical level filtering of orographic waves and lowered stratospheric wind speeds.