Tropical Cyclone Intensification and Fullness: The Role of Storm Size Configuration

• Published in: Geophysical research letters 2022-08, Vol.49 (16), p.n/a
• Main Authors: Guo, Xi, Tan, Zhe‐Min
• Format: Article
• Language: English
• Subjects: Amplification; Configurations; Cyclones; Hurricanes; intensification; intensity; Relative vorticity; size; Storms; TC fullness; tropical cyclone; Tropical cyclone intensities; Tropical cyclones; Vorticity; Wind; Wind structure
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL098449

The relationships between the intensification rate (IR) and the size configuration of tropical cyclones (TCs) are investigated. Theoretically, the intensity, size configuration, and relative vorticity of TCs are intrinsically linked. TC fullness (TCF) is used to quantify the size configuration of TCs and can be expressed as the product of the critical fullness (TCF0) and the ratio of fullness (Rf). TCF0 represents the fundamental constraint on size configuration shared by TCs at a given intensity and is the lower limit of fullness, whereas Rf reveals a TC's unique wind structural feature. Intermediate TCF0 (∼0.55), moderate Rf (∼1.4), and thus high TCF (∼0.8) collectively facilitate the occurrence of a large IR of TC. Obtaining a stable and moderate Rf at low TCF0 favors the subsequent intensification of a TC. The TCF‐TCF0 diagram is proposed to illustrate the co‐evolution of TC size configuration and intensity, and to reveal how they modulate intensification. Plain Language Summary Tropical cyclone (TC) intensification forecasts have not improved significantly over time. The wind structure is considered to be one of the important internal dynamical factors that affect the intensification rate (IR) of a TC. Being one aspect of TC wind structure, the intensity plays a critical role in modulating TC IR. However, as another aspect of TC wind structure, the modulation of TC size on IR remains unclear. We adopt TC fullness to measure the configuration of inner‐ and outer‐core sizes, based on which the relationship between TC size configuration and the IR is investigated. TC fullness could be interpreted via its two components. One of them is the critical fullness, which describes the lower limit on fullness at a given intensity. The other is the ratio of fullness, which reflects the variability of fullness given the intensity. Intermediate critical fullness, moderate ratio of fullness, and thus high fullness collectively facilitate the occurrence of large IR. Therefore, in addition to storm intensity, the intensification of TCs is also modulated by size configuration. This finding could improve the understanding of TC intensification. Key Points The tropical cyclone (TC) intensity is inherently connected to its wind structure, relatively high TC fullness benefits TC intensification Critical fullness measures the intensity‐related part of TC fullness and reveals the basic size configuration given the intensity The occurrence of a large intensification rate is of