Tropical cyclones in North Atlantic could get more ferocious: paper

A recent paper by two American scientists projects an increase in the intensity of tropical cyclones in the North Atlantic and suggests an increased probability of hurricanes in the future.

The paper, dubbed Projected Increases in North Atlantic tropical cyclone intensity from CMIP5 models, was published in Journal of Climate.

The authors examine projections in a measure known as the seasonally-integrated power dissipation index (PDI), “which is a metric that convolves storm duration, frequency and intensity.”

“Our results suggest that the North Atlantic PDI, driven primarily by changes to tropical cyclone intensity and the duration of (tropical cyclones) at highest intensity, is projected to increase over the current century” in three “representative concentration pathways” cited in the report. The paper also notes the intensification is a response to both an increase in greenhouse gas emissions and aerosol changes.

The authors are Gabriel Vecchi, an oceanographer for the National Oceanic and Atmospheric Administration’s Princeton, N.J.-base Geophysical Fluid Dynamics Laboratory, and Gabriele Villarini, an assistant professor of civil and environmental engineering at the University of Iowa.

They build on an article they wrote for Journal of Climate published last February, titled North Atlantic Power Dissipation Index (PDI) and Accumulated Cyclone Energy: Statistical Modelling and Sensitivity to Sea Surface Temperature Changes. In that article, the focussed on the statistical modeling for both the PDI and another metric, dubbed accumulated cyclone energy (ACE), for the North Atlantic from 1949 until 2008.

Vecchi and Villarini’s most recent article examines projected changes to PDI by applying the statistical model of their earlier study to outputs of 17 global climate models “to address questions relatd to future changes in North Atlantic tropical cycline intensity, using 1986-2005” as the reference period to compute anomalies.

They do not project a significant increase in frequency of North Atlantic tropical cyclones but the PDI increase does indicate “a projection for an increase” in intensity or the duration at which the storms are most intense, they wrote.

“All other things equal, the probability of a major hurricane occupying a place at any given time is projected to increase,” they wrote.