Comparison of the Characteristics and Precipitation Features of Mesoscale Convective Systems in Tropical Cyclones of Different Intensity Categories over the Western North Pacific

Abstract

Abstract The mesoscale features of 400 tropical cyclones (TCs) over the western North Pacific during 2014–21 were investigated through Global Precipitation Measurement Microwave Imager and Dual-Frequency Precipitation Radar observations. An improved algorithm has been developed to identify active mesoscale convective systems (MCSs) in TCs. These MCSs are continuous systems with active precipitation, exhibiting deep convection, and only account for a small portion of the precipitating pixels within a TC. This study highlights the evolving characteristics of MCSs and their precipitation features in TCs of different intensity categories. The development and evolution of active MCSs in TCs are influenced by the degree of organization of the system. During the tropical depression stage, the maintenance of MCSs relies heavily on substantial convective precipitation pixels, especially deep convection. The convection exhibits a high echo top height and significant ice scattering feature. As the TC intensity increases, MCSs are more likely to be in a mature state where convective precipitation is no longer as crucial for their development. This transition leads to a decrease in the proportion and the 20-dBZ echo top height of deep convection in both the inner- and outer-core regions. The proportion of stratiform precipitation increases, ultimately resulting in an expansion in the MCS size and an increase in the polarization-corrected temperatures (PCTs) of MCSs. By elucidating these phenomena, this study deepens our understanding of the structure and precipitation features of TCs, providing insights into the unique characteristics of MCS development that differ from the synoptic-scale features of TC development.