North Atlantic Hurricane Winds in Warmer than Normal Seas

Jill C Trepanier

doi:10.3390/atmos11030293

Abstract

Tropical cyclones devastate coastlines around the world. The United States and surrounding areas experienced catastrophic extreme events in recent hurricane seasons. Understanding extreme hurricanes and how they change in a warming ocean environment is of the utmost importance. This study makes use of the historical, positive relationship between average summer sea surface temperatures (SSTs) and maximum hurricane wind speeds across the North Atlantic Basin from 1854–2018. Geographically weighted regression shows how the relationship between hurricane winds and SSTs varies across space. Each localized slope is used to increase historical wind speeds to represent winds in a three-degree Celsius warmer-than-average sea surface. The winds are then used to estimate the maximum intensity of the thirty-year hurricane (one with a 3.3% annual probability of occurrence) across the hexagonal grid using extreme value statistics. Viewing the results spatially allows for geographic patterns to emerge in the overall risk of major hurricane occurrence in warm SST environments. This study showcases the difference in the historical extreme compared to the potential future extreme in the hopes to better inform those charged with making important, life-saving decisions along the U.S. and neighboring coasts.

Highlights

Harrowing winds, torrential downpours, and rising storm surges are all characteristics of the extreme hurricane, the tropical tempest designed to transfer massive amounts of energy from our planet’s equator to the poles
When the threshold is at this level, it allows for each geographic location to describe its own unique hurricane risk, while still providing enough data values for the model to be robust
Extreme hurricane winds are changing. This is evidenced in the most recent hurricane seasons and is supported by the geographic and statistical approach offered in this study

Summary

Introduction

Torrential downpours, and rising storm surges are all characteristics of the extreme hurricane, the tropical tempest designed to transfer massive amounts of energy from our planet’s equator to the poles. In 2017 and 2018, only five events, i.e., Hurricanes Harvey, Irma, Maria, Florence, and Michael, took the souls of nearly 3500 people throughout the Caribbean Islands and the United States’ Gulf and East coasts [1,2,3,4]. Hurricane Harvey ranks second only to Hurricane Katrina for the costliest hurricane to ever strike the United States, causing an estimated $125 billion in damage [5]. Hurricanes Maria and Irma rank third and fifth in the list at $90 and $50 billion, respectively [5]. Many of the fastest growing urban areas around the world are located on or near coastal zones [7,8], presenting a growing risk to and heightened costs from the adverse effects of extreme hurricanes. A notion plaguing the tropical cyclone research community offers another potential reason the costs are increasing: changing hurricane frequency and intensity

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