Impact of Anthropogenic Climate Change on United States Major Hurricane Landfall Frequency

Emma L Levin,Hiroyuki Murakami

doi:10.3390/jmse7050135

Abstract

Although anthropogenic climate change has contributed to warmer ocean temperatures that are seemingly more favorable for Atlantic hurricane development, no major hurricanes made landfall in the United States between 2006 and 2016. The U.S., therefore, experienced a major hurricane landfall drought during those years. Using the high-resolution Geophysical Fluid Dynamics Laboratory 25 km grid High-Resolution Forecast-Oriented Low Ocean Resolution (HiFLOR) global climate model, the present study shows that increases in anthropogenic forcing, due to increases in greenhouse gasses, are associated with fewer long-duration major hurricane landfall droughts in the U.S., which implies an increase in major hurricane landfall frequency. We create six different fixed-distance ‘buffers’ that artificially circle the United States coastline in 100 km radial increments and can compensate for the bias in hurricane landfall calculations with six-hourly datasets. Major hurricane landfall frequencies are computed by applying the buffer zones to the six-hourly observed and simulated storm track datasets, which are then compared with the observed recorded major hurricane frequencies. We found that the major hurricane landfall frequencies generated with the 200 km buffer using the six-hourly observed best-track dataset are most correlated with the observed recorded major hurricane landfall frequencies. Using HiFLOR with an implemented buffer system, we found less frequent projections of long-duration major hurricane landfall drought events in controlled scenarios with greater anthropogenic global warming, which is independent on the radius of the coastal buffer. These results indicate an increase in U.S. major hurricane landfall frequencies with an increase in anthropogenic warming, which could pose a substantial threat to coastal communities in the U.S.

Highlights

Notable for its high frequency of six major hurricanes (MHs), the 2017 Atlantic hurricane season resulted in severe damage in the United States and Caribbean [1]
Hurricane Harvey was the most devastating MH rainfall event ever recorded in U.S history, with regions in eastern Texas experiencing over 60 inches of rainfall; Hurricane Irma was the strongest hurricane on record in the Atlantic Ocean Basin and cost the U.S $51 billion [4,5,6,7]
When the six-hourly HURDAT2 tropical cyclone (TC) tracks in the North Atlantic from 1900 to 2015 were run through all six buffers, the mean TC landfall frequency for each buffer was at least one additional event than what was recorded by National Oceanic and Atmospheric Administration (NOAA)

Summary

Introduction

Notable for its high frequency of six major hurricanes (MHs), the 2017 Atlantic hurricane season resulted in severe damage in the United States and Caribbean [1]. (1 + 0.1Vshear)−2, where η is the absolute vorticity in s−1, H is the relative humidity at 700 hPa in percent, Vpot is the potential intensity in m s−1, and Vshear is the magnitude of the vector shear from 850 to 200 hPa in m s−1 This index can be a measure of favorable or unfavorable large-scale conditions for potential TC and MH genesis. Globally seven of the ten warmest tropical sea surface temperature (SST) years on record took place during the 11-year MH landfall drought (from 2006 to 2016) [13] These factors imply that during the MH landfall drought, atmospheric and oceanic conditions were more favorable for TC and MH occurrence than in previous decades [14,15,16].

Definition of Landfall and Observation Analysis

Sensitivity of Buffer Distance to United States MH Landfall Frequencies

Impact of Anthropogenic Climate Change on MH Landfall Drought