The life cycle of an extratropical marine cyclone. Part II: mesoscale structure and diagnostics

Abstract

Horizontal analyses at 350m above ground level describe the cyclone's mesoscale frontal baroclinic structure and associated flow patterns. The vertical structure and evolution of the cyclone's cold front, warm front, and bent-back front are illustrated in cross-sectional analyses of potential temperature, wind velocity, potential vorticity (PV), front-relative transverse cross-sectional analyses of potential temperature, wind velocity, potential vorticity (PV), front-relative transverse flow vectors, diabatic heating, and PV tendencies. Of particular interest are the lower-tropospheric positive PV anomalies within the warm front and within its bent-back extension westward into the polar airstream. Airborne radar reflectivities and Doppler velocities provide a detailed account of the precipitation elements and asssociated radar reflectivities and Doppler velocities provide a detailed acccount of the precipitation elements and associated wind flow patterns in the vicinity of the fronts, including mesoconvective radar reflectivities of greater than 50 dBZ and cross-frontal convergent flow exceeding -20 × 10-4s-1. Time series of the 1-s aircraft observations show large and rapid changes in meteorological variables as the aircraft crossed the narrow frontal zones. -from Authors