Characteristics of Deep Convective Clouds, Precipitation, and Cloud Properties of Rapidly Intensifying Tropical Cyclones in the Western North Pacific

Toward the understanding of rapid intensification (RI) of tropical cyclones (TCs) in the western North Pacific, the TC's deep convective cloud (DCC), precipitation, and cloud properties in terms of cloud effective radius, optical thickness, and top height from satellite observations are investigated. Mean and radial distributions of the variables at different intensity stages and intensification categories are examined. The relationship indicates that the DCC percentage and temperature, especially their radial distributions, could be used to identify an impending RI regardless of TC intensity. Meanwhile, the mean and radial distribution of precipitation may discriminate RI from non-RI in tropical depression (TD) and tropical storm (TS). The radial distribution of the cloud properties in rapidly intensifying TD and TS also suggest that most of the clouds near the center of the storm has deepened already while those that are far from the center are generally in developing or dissipating stage. Moreover, rapidly intensifying TCs, regardless of their intensities, manifest common DCC, precipitation, and cloud properties characteristics near the TC center. It is to be noted that the different mean and radial distribution characteristics of the variables between initial and continuing stages of RI are inferred to be artifacts of their intensities and RI rates (or radius of maximum wind sizes) rather than whether the TCs are at the onset or 24 hr of RI.