Journal Article

What Are the Finger‐Like Clouds in the Hurricane Inner‐Core Region?

Harris, Lucas, Mouallem, Joseph, Gao, Kun

2024

Overview

Finger‐like km‐scale features have been observed along the inner‐edge of the eyewall of intense hurricanes. But due to the limited availability of observations, many important aspects of these features remain unknown. In this study, we aim to offer insights on the nature of these phenomena based on a four‐day‐duration O(100 m) grid spacing simulation that covers the inner‐core region of an idealized hurricane. The simulation successfully captured the finger‐like features, which closely resemble observed ones. We propose that these features are formed due to the shear instability associated with vertical distribution of the tangential wind in the inner‐core region. This proposed mechanism offers insights on several key characteristics of the features of interest, including their emergence time, frequency, radial location and vertical extent. Our study also demonstrates the feasibility of using multi‐level nesting for O(100 m) grid spacing hurricane simulations and predictions, aligning with the goals for next generation hurricane models. Plain Language Summary The inner core region of hurricanes harbors complex dynamical features, including small‐scale clouds characterized by finger‐like appearances pointing toward the hurricane eye. These features have been frequently observed in intense hurricanes. However, many basic aspects of these features remain unknown, particularly regarding what controls their occurrence and location. We conduct a numerical simulation with a very fine (about 100 m) horizontal grid spacing to investigate the nature of these features. Our proposed mechanism explains several key characteristics of these features. Key Points We conduct a O(100 m) grid spacing simulation that captures the finger‐like features along the inner edge of the hurricane eyewall We propose a mechanism that links the finger cloud formation and hurricane‐scale dynamics This proposed mechanism explains the emergence time, frequency, radial location and vertical extent of the finger features

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Eye of hurricane / Feasibility studies / FV3 / high‐resolution / hurricane / Hurricane models / Hurricanes / inner core / Kelvin-Helmholtz instability / LES / Mathematical models / Nesting / Numerical simulations / Simulation / tropical cyclone / Vertical distribution