• By AMY WOLD
• Published: Oct 19, 2009

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A team of researchers at LSU is studying how areas of cool water in the Gulf of Mexico affect hurricane energy and how that information could be used in forecasting storm  intensity in the future.

The group, led by Nan Walker, director of the Earth Scan Laboratory at LSU, proposes that circulating eddies of cold water found near the much warmer Loop Current in the Gulf can sometimes offset the effects of warmer waters that hurricanes use to grow stronger.

These “Loop Current Frontal Eddy Cyclones” cold water  features that swirl around the Loop Current are intensified when they come in contact with hurricanes, the group reports.

The hurricane winds speed up the rotation of the cold water cyclones, forcing cold water from a depth of about 150 feet to the surface, researchers say.

The rapid “upwelling” of cold water sometimes reduces the water temperature below the temperature thought to sustain hurricanes — about 80 degrees Fahrenheit, researchers say.

Two to four of these cyclones are normally found circling around the margin of the Loop Current, Walker said.

But the cyclones are difficult to track because they move rapidly and because they’re not visible using satellite imagery of the surface temperature because the cold water does not usually reach the surface, she said.

During non-storm times, these “lows” in the ocean’s surface can be identified by the fact that they are lower in elevation — on average about three feet lower — than the near-by warm water Loop Current, Walker said.

However, when a hurricane crosses over or near one of these cold cyclones, the upwelling of cold water can be detected in satellite data of temperature gathered by the LSU’s Earth Scan Laboratory every 15 minutes, she said.

During Hurricane Ivan in 2004, the skies over the Gulf cleared up soon after the storm passed and allowed the researchers to see these cool wakes left by the hurricane, Walker said.

By studying the wind speeds along Ivan’s track, it became apparent that the cool wakes weakened the hurricane. “As the hurricane generates cool water, it’s rapidly effected by it,” Walker said.

These cool wakes form to the right of the storm track where the wind is stronger and directions are more favorable to upwelling of cold water, Walker said.

“We’ve been using all the data we can find to study these cool wakes,” Walker said. “Some that we capture with our antennas and some that we obtain from other research labs.”