Scientists study atmospheric waves radiating out of hurricanes

May 16, 2017
The red curve shows the leading edge of a packet of gravity waves radiating outward at the top of Typhoon Meranti on Sept. 12, 2016. Credit: Visible image the Himawari satellite, maintained by the Japan Meteorological Agency, and processed by Brian McNoldy, University of Miami Rosenstiel School of Marine and Atmospheric Science

Researchers believe they have found a new way to monitor the intensity and location of hurricanes from hundreds of miles away by detecting atmospheric waves radiating from the centers of these powerful storms.

In a new study, scientists from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science and the Hurricane Research Division of the National Oceanic and Atmospheric Administration (NOAA) presented direct observations of the waves, obtained by NOAA aircraft flying in hurricanes and by a research buoy located in the Pacific Ocean. The waves, known as , are produced by strong thunderstorms near the eye and radiate outward in expanding spirals.

"These very subtle waves can sometimes be seen in images," said David Nolan, professor in the Department of Atmospheric Sciences, and lead author of the study. "We were able to measure them in aircraft data and surface instruments."

In addition, says Nolan, computer simulations performed at the UM Center for Computational Science can reproduce the waves, showing that the wave strengths can be related to the maximum wind speed in the core of the storm. These findings suggest that hurricanes and typhoons could be monitored from hundreds of miles away with relatively inexpensive instruments, such as barometers and anemometers, much like earthquakes from around the world are monitored by seismometers.

Animation of visible images of Typhoon Meranti was taken from the Himawari satellite, every 2 1/2 minutes over three hours. Credit: David Nolan and Brian McNoldy, University of Miami Rosenstiel School of Marine and Atmospheric Science

The researchers analyzed data obtained from 25 different penetrations by NOAA P3 aircraft into five hurricanes in 2003 and 2004, as well as data from the Extreme Air-Sea Interaction (EASI) buoy deployed in the Pacific Ocean by UM Rosenstiel School scientists in 2010.

"The waves cause very weak upward and downward motions, which are recorded by the NOAA P3 as it flies through the storm," said Jun Zhang of the Hurricane Research Division, a veteran of many flights. "But we were surprised at how clearly the waves could be detected at the surface."

"Of course, hurricanes are very well observed by satellites. But these waves can reveal processes occurring in the eyewall of a hurricane that are obscured from the view of satellites by thick clouds," said Nolan. "Any additional measurements, even if they provide similar information as satellites, can lead to better forecasts."

Explore further: US forecasts 'near-normal' hurricane season

More information: David S. Nolan et al, Spiral gravity waves radiating from tropical cyclones, Geophysical Research Letters (2017). DOI: 10.1002/2017GL073572

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BubbaNicholson
1 / 5 (1) May 17, 2017
Hurricane Matthew was mitigated by deploying soy bean oil and canola oil to the ocean surface. Deployments of hundreds of gallons of oil were made into rivers and streams on Florida's east coast, timed to meet Hurricane Matthew with a wind-killing monolayer oil sheen a hundred square miles in surface area. Deployment succeeded in diminishing windspeed, increasing visibility, destroying the eye of the storm momentarily, dropping the storm down a category and reducing its forward progress. Oil deployed in Daytona Beach, St. Augustine, and Jacksonville halted storm surge immediately.
barakn
not rated yet May 17, 2017
The warm eddies responsible for hurricanes like Matthew have a surface area of very roughly 200,000 km^2. An oil monolayer is roughly 2 nm thick, or 2 * 10^-12 km thick. Thus 4 x 10^-7 cubic km of oil is needed. That's 400 cubic meters or 106,000 gallons of oil. This totally neglects the fact that the ocean is loaded with surfactants and hungry bacteria, which would increase the required amount of oil considerably. Also if you released the oil prior to the hurricane's arrival, the wind would have been from the East and would have pushed your oil onto the beach where it would have stuck to the sand. We should also consider that there's a release of natural and artificial oils into the Atlantic on a daily database that dwarfs your addition. The fact that the winds diminished and visibility improved was a sign that the hurricane was losing energy after moving over land and had nothing to do with your little experiment. My conclusion is that you are delusional.

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