? A Fundamental Property of Atmospheric Circulation

Abstract

FIVE or six years ago, in reports to the Meteorological Research Committee, I analysed the air-mass transport in vertical cross-sections of the circulations between cyclones and anticyclones¹. One of the results reached was that the horizontal air-mass transport (ρv) reaches a maximum, not at the tropopause, but rather lower, often at about the 8-km. level. This level, indeed, seems to be the boundary between two circulations in the vertical plane; the lower circulation involves upward motion in the cyclone, thence horizontal transfer towards the anticyclone, thence subsidence in the anticyclone; the upper circulation involves subsidence in the cyclone, including subsidence in the stratosphere, thence horizontal transfer towards the anticyclone, thence ascent of air, both in the upper part of the troposphere and in the stratosphere of the anticyclone. The influence of such circulations in causing variations in the height of the tropopause was discussed.