The Importance of Shallow and Moderate Precipitation in the Upshear Quadrants to Tropical Cyclone Rapid Intensification as Derived from 14 Years of TRMM Data

There has been a long-standing uncertainty about the relative importance of deep/very deep convection vs. shallow/moderate precipitation for rapid intensification (RI) of tropical cyclones (TCs). Many previous observational case studies have shown horizontally small-scale, asymmetric deep convection (such as convective bursts and hot towers) within the inner core of TCs, which are deemed as being important for RI. This talk examines shear-relative distributions of precipitation/ convection in tropical cyclones using 14 years of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) data, which suggests a different conclusion. Evidence is accumulating to suggest that RI is more likely triggered by the increase of shallow-to-moderate precipitation, especially in the upshear quadrants, and the appearance of more moderately-to-very deep convection in the middle of RI is more likely a response or positive feedback to changes in the vortex.