Singularity as a diagnostic for secondary eyewall occurrence in tropical cyclones

TL;DR

This paper introduces a simple diagnostic based on a singularity that predicts secondary eyewall formation in tropical cyclones using basic storm parameters, aiding in better forecasting and understanding of these phenomena.

Contribution

The study presents a novel, straightforward diagnostic method relying on three key storm characteristics to predict secondary eyewall occurrence in tropical cyclones.

Findings

Diagnostic compares well with satellite observations

Predicts secondary eyewall formation using minimal data

Enhances understanding and modeling of TC intensity changes

Abstract

Secondary eyewalls occur in 70% of major tropical cyclones (TCs), and are associated with rapid changes in storm intensity and rapid broadening of strong winds. While mechanisms of secondary eyewall formation have been investigated from various perspectives, the explicit conditions on which secondary eyewalls occur in TCs remain veiled, leaving substantial uncertainties in TC intensity forecast, especially for the most extreme events. In this study, we present a simple diagnostic, in form of a singularity, for secondary eyewall occurrence in TCs. The diagnostic is solely dependent on three basic storm characteristics (the maximum wind speed, the radius of maximum wind, and the latitude) and shown to compare well with satellite observations. It provides a valuable tool to improve the understanding, modeling and risk assessment of secondary eyewall storms.