PV FRONTOGENESIS AND UPPER-TROPOSPHERIC FRONTS

Upper-tropospheric fronts and frontogenesis are viewed from a potental vorticity (PV) perspective. The rudiments of this approach are to reg ard such a front as a zone of strong PV gradient on isentropic surface s, and to treat the accompanying frontogenesis as the process whereby this gradient is enhanced on trepopause-transcending isentropic surfac es. A case study suggests that this concept of PV frontogenesis provid es a concise dynamically based definition of upper-level frontal zones , and a compact and transparent approach for diagnosing the frontogene sis. The concept provides fresh insight on the dynamics of the upper-l evel fronts, and has the potential to shed light on related phenomena and processes.