Role of Shallow and Moderate Convection in the Tropical Cyclone Intensification Process

Tropical meteorologists have long appreciated that deep convection plays a critical role in tropical cyclone (TC) intensification, however this research points to the important role of shallow and moderate convection (SAM) for TC intensification, especially for rapid intensification (RI). This has not been previously apparent because of inability to monitor, before the advent of of low-frequency passive microwave (PMW) that is sensitive to rain. These data revealed early eye development within the low to mid-level cloudiness. These include an indicator for RI in next 24 hours and in other cases what appears to be early eyewall replacement cycles (ERCs).

The approach utilized a case study of a combination of a database of PMW overpasses, data from simultaneous aircraft missions, coincident radar imagery, and simulated satellite imagery. The results indicate a consistent set of patterns of SAM prior to the onset of RI. Forecasters are aware of the significance of these patterns, however more research is needed to link them to the dynamics of the TC.