Large-eddy simulation of the rapidly intensifying tropical cyclone Soudelor (2015)

Abstract

The lack of dense observations of tropical cyclones (TCs) far out at sea hinders mankind's understanding of their multiscale physics. Large-eddy simulation (LES) provides a potential surrogate considering its ability to reproduce the fine structures of a wide range of atmospheric flows including TC. In this study, an LES is carried out to reproduce the rapid intensification of TC Soudelor (2015). Comparisons with both observations and previous modeling studies indicate that the LES produces a reasonably accurate depiction of the TC structure, including the active rainbands, the remarkable secondary circulation and typical double warm cores. Notably, the LES captures exclusive features of the TC, such as the tornado-scale vortices (TSVs) reported in previous LES studies at much finer horizontal resolution. Local gust winds in these vortices are related to the unexpected minimum sea-level pressure, which may affect the determination of the TC intensity. To address this issue, a tractable correction algorithm is developed based on the systematic analysis of TSVs. This algorithm aims to help researchers better interpret the booming LESs of TC both at present and in the future.