Tropical cyclone waves detected with infrasound sensor array

Jan 15, 2013

The strong winds of a tropical cyclone whip up the sea surface, driving ocean waves a dozen meters (about 40 feet) high. When one such ocean wave runs into another wave that has an equal period but is traveling in the opposite direction, the interaction produces low-frequency sound waves that can be detected thousands of kilometers away. Known as microbarom, the infrasound signals produced by interacting ocean surface waves have typical frequencies around 0.2 hertz.

Researchers previously determined that as a hurricane travels along its track, waves generated by the storm earlier in time will interact with those generated later on, producing a strong microbarom signal in the storm's wake. Researchers also found, however, that microbarom signals are produced by regular behavior, including swell, surface waves, or non-tropical cyclone storms.

To identify how tropical cyclone-produced waves interact with ambient surface , and to determine whether the tropical cyclone microbarom signal could be isolated from the background noise, Stopa et al. examined the infrasound signals detected by an International Monitoring System infrasound in Hawaii during the passage of Hurricanes Neki and Felicia in 2009.

The authors used modeled wind speeds to simulate the wave conditions during the hurricanes, then used these estimates to drive an acoustic model that enabled them to calculate the microbarom infrasound activity. They find that the microbarom signals observed by the Hawaiian sensor array aligned with their modeled estimates. The authors note that the infrasound signal of the cyclone-generated waves tended to swamp the detectors, drowning out the much weaker signals of the ambient wave interactions. They suggest that given further refinements, measuring the infrasound signal of microbarom waves could be a good way to detect and measure the wave conditions near a tropical cyclone.

Explore further: Mexico's Volcano of Fire blows huge ash cloud

More information: Atmospheric infrasound from nonlinear wave interactions during Hurricanes Felicia and Neki of 2009, Journal of Geophysical Research - Oceans, doi: 10.1029/2012JC008257 , 2012

add to favorites email to friend print save as pdf

Related Stories

Langmuir circulation inhibits near-surface water turbulence

Jun 18, 2012

In the surface ocean, breaking waves are a major source of air bubbles and turbulent kinetic energy. During the presence of a consistent surface wind, these wave-generated bubbles, along with other surface material like seaweed ...

The inaudible symphony analyzed

Nov 03, 2008

By measuring 'inaudible' sounds, events like illegal nuclear tests can be detected. This 'infrasound' can also help us understand more about the upper atmosphere, according to Läslo Evers. Evers will receive a PhD based ...

Ocean surface loses resistance during extreme hurricanes

Sep 18, 2012

TU Delft researchers have discovered that the ocean surface loses practically all aerodynamic resistance during hurricanes with extremely high wind speeds. This occurs as a result of a very smooth layer lying ...

Climate models should include ocean waves

Jun 14, 2012

(Phys.org) -- A new field study by researchers from Swinburne University of Technology suggests that the effect of wave activity on oceans should be incorporated in long term climate and weather prediction ...

Recommended for you

Erosion may trigger earthquakes

Nov 21, 2014

Researchers from laboratories at Géosciences Rennes (CNRS/Université de Rennes 1), Géosciences Montpellier (CNRS/Université de Montpellier 2) and Institut de Physique du Globe de Paris (CNRS/IPGP/Université Paris Diderot), ...

Strong undersea earthquake hits eastern Indonesia

Nov 21, 2014

A strong undersea earthquake hit off the coast of eastern Indonesia on Friday, but there were no immediate reports of injuries or serious damage and officials said it was unlikely to trigger a tsunami.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.