Distributions of convection in rapidly intensifying tropical cyclones

Distributions of very deep convection (defined as 20 dBZ radar echo penetrating 14 km) in rapidly intensifying (RI) tropical cyclones (TCs) are statistically quantified using 14 years of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) data between 1998-2011. The dataset includes 818 northern hemisphere tropical storms through category 2 hurricanes with at least moderately favorable environmental conditions. Four categories of storms are classified by future 24-hour intensity change. The azimuthally averaged analysis shows that the percent occurrence of very deep convection for RI storms is only slightly higher than that for slowly intensifying (SI) storms with 40-km radius, but becomes the lowest among four intensity change categories beyond 40 km. TCs in each category are combined into composite images relative to environmental vertical wind shear vector. Very deep convection is quite rare in TCs, with a maximum occurrence below 3.5%. But it contributes a disproportionate amount to total volumetric rain and latent heating, with a maximum contribution around 20% and 30%, respectively. Very deep convection is mainly located at the left of shear. But in RI storms, it spreads more to the right of shear. Compared with other intensity change categories, storms prior to RI has the lowest percentage of total volumetric rain and latent heating from very deep convection, and the contribution of very deep convection for RI storms concentrates within the inner 50 km. Preliminary results also suggest that deep convection (with 20 dBZ radar echo height ≥ 10 km) rather than very deep convection is more important in the contribution of convection to total volumetric rain and latent heating in RI storms.