Cooler waters help diminish Isaac's punch

Aug 29, 2012 by Alan Buis
Color-enhanced image of sea surface heights in the Gulf of Mexico, showing Hurricane Isaac's path through the Gulf and around its warmest waters. Image credit: LSU Earth Scan Laboratory/U. of Colorado CCAR/NASA-JPL/Caltech

(Phys.org)—Seven years after the powerful Category 3 Hurricane Katrina caused widespread devastation along the Gulf Coast, a Category 1 Hurricane Isaac, with maximum sustained winds of 80 miles per hour (70 knots), is making landfall today in southeast Louisiana. And one of the reasons why Isaac is not Katrina is the path it took across the Gulf of Mexico and the temperature of the ocean below, which helps to fuel hurricanes.

In 2005, 's maximum wind speeds increased dramatically as the storm passed over a warm ocean circulation feature called the Loop Current that is part of the Gulf Stream. The storm evolved quickly from a Category 3 to a Category 5 event on the Saffir-Simpson in a matter of nine hours as it drew heat from the Loop Current. It subsequently dropped in intensity to a Category 3 storm at landfall.

Because the Loop Current and its eddies are warmer, and thus higher in surface elevation, than the surrounding waters, they are easily spotted by satellite altimeter instruments, such as those aboard the NASA/ Jason 1 and Ocean Mission/Jason 2 satellites. Scientists use the latest satellite measurements of sea-surface height from these and other satellite altimeters to create maps showing the location, direction and speed of currents in the Gulf of Mexico.

This color-enhanced image of sea surface heights in the northeastern Gulf, produced using data from available satellite altimeters, including NASA's Jason-1 and Jason-2 satellites, shows Isaac's path through the Gulf. The storm skirted around the Loop Current, then caught the outer edge of a warm eddy before passing directly over a cold eddy. The storm's track away from the Gulf's warmest waters has helped to keep Isaac from intensifying rapidly, as Hurricanes Katrina and Rita did in 2005.

Warm eddies have high heat content and great potential to intensify hurricanes, whereas cold eddies have low heat content and may even cause hurricanes to weaken, as was the case with Hurricane Ivan in 2004.

Explore further: Satellites can improve regional air quality forecasting

Related Stories

NASA Satellites Keep Watch on Gulf Current Near Spill

May 25, 2010

(PhysOrg.com) -- Scientists and agencies monitoring the oil spill in the Gulf of Mexico are keeping a wary eye on changes in the nearby Loop Current, a warm ocean current that is part of the Gulf Stream.

Researchers make hurricane predictions more accurate

May 24, 2006

The hurricane forecasting model developed by University of Rhode Island and NOAA scientists – the most accurate model used by the National Hurricane Center over the last three years – has been improved ...

Hurricane Igor, unchained, in NASA satellite images

Sep 20, 2010

While its intensity has dropped slightly, massive Hurricane Igor remains a powerful Category Three storm, with maximum sustained wind speeds of 105 knots (115 miles per hour) as it continues on a projected ...

Envisat Images Hurricane Gustav

Sep 05, 2008

The development and path of Hurricane Gustav is shown via a sequence of satellite images acquired by Envisat's Medium Resolution Imaging Spectrometer (MERIS) instrument on 25 August, 28 August, 30 August and ...

Recommended for you

Storm chasers take on supercell thunderstorms in Bangladesh

3 hours ago

This past April, Scott Olson touched down in Bangladesh to become the country's first known storm chaser. On the other side of the world, back in Oklahoma, Tim Vasquez and a team of meteorologists worked tirelessly to put ...

Slope on the ocean surface lowers the sea level in Europe

4 hours ago

Research at the National Oceanography Centre (NOC) has discovered that a 'slope' on the ocean surface in the Strait of Gibraltar is lowering the sea level in Europe by 7cm. This research, published today in Geophysical Re ...

Climate models don't over-predict warming, study shows

7 hours ago

If you listen to climate change skeptics, Earth's surface hasn't warmed appreciably in the last 15 years, and any "record" set last year is just the result of the planet doing what the planet naturally does.

GPM sees nor'easter dump snow on New England

19 hours ago

At 5:05 p.m. EST Monday, Jan. 26, 2015, the Global Precipitation Measurement mission's Core Observatory flew over the Nor'easter that dumped snow on New England. This satellite image shows the rate of rainfall, with low amounts ...

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.