Atmospheric
gravity waves that spiral outward could be used to monitor storms
University
of Miami’s Rosenstiel School
EDITOR’S NOTE: Here we have another example of endangered science,
the kind that Trump wants to defund and erase. After all, climate change and its effects can't happen if you don't know about them. - W. Collette
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
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