Quasigeostrophic potential vorticity in isentropic coordinates

Abstract

An isentropic coordinate form of quasigeostrophic potential vorticity is derived. Compared with the well-known height and pressure coordinate versions, this isentropic form is more clearly related to Ertel's potential vorticity and the derivation from it is much simpler. A derivation from quasigeostrophic approximations to the governing equations is also given and the boundary conditions to be applied on isentropic surfaces are discussed. Analogous developments using isopycnal coordinates are given assuming an incompressible fluid model. -Authors