THE LIFE-CYCLE OF A SIMULATED MARINE CYCLONE - ENERGETICS AND PV DIAGNOSTICS

The life cycle of an intense marine cyclone is documented in this pape r. The departure of the moist dynamics From the dry baroclinic dynamic s is explored from an energetics point of view. The contributions of v arious physical processes through the life cycle to the low-level cycl onic circulation is computed using a recently developed PV (potential vorticity) inversion technique. The moist cyclone deviates most from t he dry cyclone during the early rapid spinup period with significant m esoscale features associated with the warm and bent-back warm frontal zones. However, from an energetics point of view, the moist cyclone po ssesses a very similar, but enhanced, growth and decay rate during its life cycle. The transports of heat and momentum fluxes are also stren gthened. The enhancement of eddy kinetic energy due to condensation ac counts for nearly 50% of the maximum eddy kinetic energy generated in the moist cyclone.From a PV perspective, the main difference between t he 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 cyclolyt ic effect of decreasing the surface thermal anomaly and the cyclogenet ic effect of increasing the upper-level wave deepening. In the mature stage when the growth has almost ceased, the dry cyclone also possesse s upper- and lower-level PV anomalies very similar to the moist cyclon e. Based on these results, the authors conclude that, except for the m esoscale structural differences and their associated interactions duri ng the early rapid spinup period, the moist cyclone exhibits an enhanc ed growth rate (and decay rate as well) but appears dynamically simila r to the dry cyclone from an energetics point of view as well as in te rms of ''PV thinking.''