Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hurricanes at the Equator: "Impossible Perfect Storm" Observed

13.05.2003


Hurricanes cannot form near the equator, or so meteorology textbooks maintain. But a storm named Typhoon Vamei upended scientists’ thinking when it swirled above the equator in the South China Sea near Singapore on December 27, 2001. It formed so close to the equator that its winds howled in both hemispheres.


The Modis satellite image shows Typhoon Vamei at 1.5 degrees North near Singapore on December 27, 2001, with circulation on both sides of the equator. The land areas are the Malay Peninsula and Sumatra to the west of the typhoon, and Borneo to the east.
Satellite Image Credit: CRISP/National University of Singapore



New research funded by the National Science Foundation (NSF) and the U.S. Navy’s Office of Naval Research reveals the unusual mechanism for the birth of such a storm.

Intense thunderstorms over expanses of warm ocean water roil the atmosphere. Earth’s rotation spins these storms through the Coriolis Effect, a deflection that results in storms whirling counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.


The quiescent region for this force (much like the "eye" of a hurricane) is at the equator, so researchers once believed nascent storms in this region could not build the power to start spinning. Before Typhoon Vamei (hurricanes are called typhoons when they form over the Pacific Ocean), no hurricane in recorded history had formed within 200 miles of the equator.

"Typhoon Vamei happened because of two interacting systems, a weak circulation that formed over Borneo and drifted into the southern tip of the South China Sea and remained there, and a strong and persistent northeast wind surge that turned as it crossed the equator and created a large background rotation," explained NSF-awardee C.P. Chang, a meteorologist at the Naval Postgraduate School in Monterey, Calif. Chang collaborated with meteorologists C.H. Liu from the Chinese Culture University and H.C. Kuo from the National Taiwan University, both sponsored by Taiwan’s National Science Council.

"The mechanism we identified raises additional questions," remarked Chang. "Both the wind surge and the Borneo thunderstorms are common features of the winter monsoon. Why was an equatorial cyclone not observed before?"

From analyses of weather model and satellite data, the researchers found that the land-sea terrain in the equatorial South China Sea, while necessary for strengthening and turning the cross-equatorial wind surge, also places a time constraint on the confluence of events that occurred in December of 2001. Nonetheless, Vamei still wreaked havoc: U.S. Navy ships were damaged by the typhoon, and the southern Malay Peninsula was flooded by storm surges from its 87-mile-per-hour winds.

"When something like this happens—intense background winds wrapping around a weak disturbance that lingers over warm ocean waters—and that vortex starts to spin with no help from Earth’s rotation, unlikely factors have come together," said Chang. "What you have then is just about ’the perfect storm.’ The probability of a similar equatorial development is estimated to be once every 100 to 400 years, and it probably cannot happen outside the southern South China Sea."


NSF Science Expert: Pam Stephens, pstephen@nsf.gov
NSF Principal Investigator: C. P. Chang, cpchang@nps.navy.mil

Cheryl Dybas | NSF
Further information:
http://www.nsf.gov/od/lpa/news/03/tip030512.htm

More articles from Earth Sciences:

nachricht Climate change weakens Walker circulation
20.10.2017 | MARUM - Zentrum für Marine Umweltwissenschaften an der Universität Bremen

nachricht Shallow soils promote savannas in South America
20.10.2017 | Senckenberg Forschungsinstitut und Naturmuseen

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>