We should use central pressure deficit, not wind speed, to predict hurricane damage

Hurricane Katrina, 2005 – The air pressure, another indicator of hurricane strength, at the center of this Category 5 storm measured 902 millibars, the fourth lowest air pressure on record for an Atlantic storm. The lower the air pressure, the more powerful the storm.
[image credit: Jeff Schmaltz, NASA/GSFC]

This is supported by Hurricanes – Science and Society, which says:
‘It is well accepted that the most influential factor in storm surge generation is the central pressure deficit, which controls the intensity of a hurricane, i.e. wind velocity and stress over the ocean surface and inverse barometric effects.’

The system for categorizing hurricanes accounts only for peak wind speeds, but research published in Nature Communications explains why central pressure deficit is a better indicator of economic damage
from storms in the United States, reports Phys.org.

“Sandy is the classic example. It was a very big storm, but in terms of maximum wind speed it was arguably not a hurricane,” said Dan Chavas, an assistant professor of atmospheric science at Purdue University who led the study. “If you looked at the central pressure deficit, you would have expected it to cause a lot of damage. But if you used maximum wind speed, as people usually do, you wouldn’t expect it to do the damage that it did.”

Central pressure deficit refers to the difference in pressure between the center of the storm and outside it. Pressure and wind speed have been used interchangeably to estimate potential damage from hurricanes for years, but the relationship between them has been a long-standing riddle in tropical meteorology.

Chavas and his colleagues have defined a theory that solves that riddle. Previous work has observed that central pressure deficit depends on maximum wind speed, storm size, and latitude, but Chavas’ team has determined why that is.

Scientists could use this theory to calculate peak wind speed if they had numbers for the other metrics in the equation, which could come in handy because wind speeds need to be measured at several points of a storm, making it difficult to get an accurate reading.
The research team tested their theory on two simulations of Earth.

The first used the actual distribution of sea surface temperatures and solar radiation since 1979 to produce conditions similar to real historical climate.

The second simulation produced a very simplified version of the Earth. It had no land, and ocean temperature and solar radiation were the same everywhere. This made the entire planet sort of like the tropics, meaning hurricanes could pop up anywhere – but they still tended to form at low latitudes and move westward and toward the poles, like they do on Earth.

Continued here.

More information: Daniel R. Chavas et al,
Physical understanding of the tropical cyclone windpressure relationship, Nature Communications
(2017). DOI: 10.1038/s41467-017-01546-9