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Last Updated: Tuesday, 23 January 2007, 01:59 GMT
Experts seek clues to hurricane births
By Peter Greste
BBC News, Senegal

A satellite image of Hurricane Katrina off the coast of Florida
Experts want more warning of huge storms like Hurricane Katrina

US atmospheric scientist Greg Jenkins takes his job hunting hurricanes off the coast of West Africa very personally.

"I had a lot of friends and relatives who really suffered when Hurricane Katrina hit New Orleans," he said.

"If we can get a better understanding of how these things form here in West Africa, we'll be able to extend our forecasting, and give people more time to get out of the way."

Mr Jenkins has swapped his job in Howard University in Washington, DC for Dakar university in Senegal.

With his colleagues, he watches a short animated film again and again - satellite images of clouds over West Africa; the swirling, turbulent masses of moisture mixing and blending and separating in a mind-bogglingly complicated dance.

Outside, beneath the real black and grey clouds, wind turbines churned, harvesting data that is helping the scientists make sense of their mission.

This is to understand the weather systems that form over West Africa, head out across the Atlantic Ocean, and spin up into devastating hurricanes that ultimately batter the United States East Coast.

Saharan air

The project is called the "Nasa African Monsoon Multidisciplinary Analyses" (Namma) and as the name implies, it draws in experts from a range of disciplines.

The team of technical and scientific brains came from Nasa, and an array of American universities, and French and Senegalese institutions.

Sands of the Sahara desert
Storm systems from the Sahara can turn into severe hurricanes

Between 80 and 100 storm systems form each year as bodies of hot, dry air over the Sahara Desert, pick up moisture as they move out across the Atlantic.

They get their initial power and instability from the difference in temperature between the very hot Sahara air and the substantially cooler air along the coast of the Gulf of Guinea.

Most peter out, shedding their energy along the way, but a few - about 10% - build power, becoming great, hulking behemoths that smash their way through the Caribbean Islands, and into the United States and Mexico.

Mr Jenkins and his team want to know what makes a hurricane.

To do it, they assembled an impressive array of technology: Nasa weather satellites provided sophisticated imagery from above; radars based in Senegal and the Cape Verde Islands further west gave a long-range view from the ground.

One of the radar analysts, atmospheric scientist Paul Kucera, said the West African weather systems are poorly understood.

"What we're learning is how storms evolve in this part of the region... their dynamics, their life-cycle, their internal characteristics that are unique to this region, that have never really been observed before by radar," he said.

Inside storm systems

But while the satellites and radar give important clues about what is going on inside the storms, neither are substitutes for a first-hand look.

To do that, the team called on two aircraft crammed with sophisticated sensors - a French Falcon and a DC-8 from Nasa - that flew through the heart of the storms to complete the picture.

Map of Senegal

Back at the Dakar university, the scientists debated which of the storms to send the Falcon through.

"It's really important that we find the weather systems that will build into hurricanes," said Mr Jenkins.

"The aircraft collects all sorts of data that we couldn't get any other way. It gives us a much better understanding of what's going on inside the storm systems; and helps us calibrate the satellites and understand what they are telling us from above."

The field work ended last September, but the researchers are continuing to analyse the mountain of data they managed to harvest.

Mr Jenkins believes it could be years before they come up with any definitive results, but they will ultimately improve the accuracy of existing forecasting models.


SEE ALSO
Dust 'affects hurricane activity'
10 Oct 06 |  Science/Nature
One year on: Katrina's legacy
24 Aug 06 |  Americas
Hurricanes and global warming - a link?
23 Sep 05 |  Science/Nature
Animated guide: Hurricanes
01 Jun 05 |  Science/Nature
Country profile: Senegal
18 Jan 07 |  Country profiles
Timeline: Senegal
18 Jan 07 |  Country profiles

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