The Life Cycle of a Simulated Marine Cyclone: Energetics and PV Diagnostics

Abstract

The life cycle of an intense marine cyclone is documented in this paper. The departure of the moist dynamics from the dry baroclinic dynamics is explored from an energetics point of view. The contributions of various physical processes through the life cycle to the low-level cyclonic circulation is computed using a recently developed PV (potential vorticity) inversion technique. The moist cyclone deviates most from the dry cyclone during the early rapid spinup period with significant mesoscale features associated with the warm and bent-back warm frontal zones. However, from an energetics point of view, the moist cyclone possesses a very similar, but enhanced, growth and decay rate during its life cycle. The transports of heat and momentum fluxes are also strengthened. The enhancement of eddy kinetic energy due to condensation accounts for nearly 50% of the maximum eddy kinetic energy generated in the moist cyclone. From a PV perspective, the main difference between the moist cyclone and the dry cyclone is the production of a low-level PV anomaly during the early rapid spinup period. The cold advection in association with the circulation due to this anomaly has the cyclolytic effect of decreasing the surface thermal anomaly and the cyclogenetic effect of increasing the upper-level wave deepening. In the mature stage when the growth has almost ceased, the dry cyclone also possesses upper- and lower-level PV anomalies very similar to the moist cyclone. Based on these results, the authors conclude that, except for the mesoscale structural differences and their associated interactions during the early rapid spinup period, the moist cyclone exhibits an enhanced growth rate (and decay rate as well) but appears dynamically similar to the dry cyclone from an energetics point of view as well as in terms of ?PV thinldng.?