Towards a PV-θ view of the general circulation

Abstract

In recent years, there has been a resurgence of interest in using isentropic coordinates and Rossby-Ertel potential vorticity (PV) for diagnosing the behaviour of middle latitude synoptic systems. Such a PV-θ analysis may also prove important in providing insight into the global circulation of the atmosphere. A three-fold division of the atmosphere is discussed. The "Overworld' is the region encompassed by isentropic surfaces that are everywhere above the tropopause. In the "Middleworld', the region with isentropes crossing the tropopause but not striking the Earth's surface, the isentropic zonal and time mean of PV exhibits interesting regions of enhanced and diminished gradients. -from Author