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Scientists Study Atmospheric Waves Radiating out of Hurricanes

Atmospheric gravity waves that spiral outward could be used to monitor storms

MIAMI—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 atmospheric gravity waves, are produced by strong thunderstorms near the eye and radiate outward in expanding spirals.

“These very subtle waves can sometimes be seen in satellite 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.

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 hurricane 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.”

The study, titled “Spiral Gravity Waves Radiating from Tropical Cyclones,” was published April 30, 2017 in the journal Geophysical Research Letters. The National Science Foundation (grant #AGS1132646) and NOAA Hurricane Forecast Improvement Program (grant #NA14NWS4680028) provided funding for the study.

Typhoon Meranti GW Animation VIDEO: https://youtu.be/VaNK5dckRcQ

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About the University of Miami’s Rosenstiel School
The University of Miami is one of the largest private research institutions in the southeastern United States. The University’s mission is to provide quality education, attract and retain outstanding students, support the faculty and their research, and build an endowment for University initiatives. Founded in the 1940’s, the Rosenstiel School of Marine & Atmospheric Science has grown into one of the world’s premier marine and atmospheric research institutions. Offering dynamic interdisciplinary academics, the Rosenstiel School is dedicated to helping communities to better understand the planet, participating in the establishment of environmental policies, and aiding in the improvement of society and quality of life. For more information, visit: www.rsmas.miami.edu.

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Caption: The red curve shows the leading edge of a packet of gravity waves radiating outward at the top of Typhoon Meranti on September 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 & Atmospheric Science.

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atmospheric •  study of hurricanes •