Pvectors as a Diagnostic Tool for Synoptic-Scale Circulations

Abstract

Abstract The quasigeostrophic geopotential tendency equation is derived using P vectors in both pressure and entropy coordinates. This vector form of the geostrophic forcing in the geopotential tendency equation is similar to the Q-vector form of the ω equation. It is shown that the horizontal components of P are the advection of geostrophic momentum and the vertical component of P is the horizontal temperature advection. The P vectors are shown to be related to Q and C vectors, as well as the ageostrophic circulation. The three-dimensional pseudocurl of the P vector gives the C vector that equals the ageostrophic pseudovorticity in the quasigeostrophic model. The horizontal components of the pseudocurl of P are perpendicular and proportional to the Q. The horizontal divergence of the P vector is the geostrophic absolute vorticity advection while the three-dimensional divergence of the P vector is the geostrophic quasigeostrophic potential vorticity advection. The ageostrophic wind can be partitioned into...