Huge African dust clouds could be new hurricane tool
Pastor Dale Morgan
Huge African dust clouds could be new hurricane tool*
20 May 2008 21:41:11 GMT
Source: Reuters
By Jim Loney
MIAMI, May 20 (Reuters) - A new forecasting tool launched by a U.S.
university on Tuesday will track huge clouds of African dust over the
Atlantic Ocean as a possible indicator of the severity of a coming
hurricane season.
The technique launched by researchers at the University of
Wisconsin-Madison may help weather watchers, energy and commodities
traders and anyone else riveted by hurricane predictions to gauge what
might be coming in cyclone-prone areas of the Atlantic and Caribbean.
Dust storms originating in the Sahara Desert are believed to affect
Atlantic hurricanes by blocking the amount of sunlight hitting the
ocean. Hurricanes draw their energy from warm sea water.
Amato Evan, a pioneer of research into the links between Saharan dust
and hurricanes, said the first seasonal forecast calls for an average
amount of dust and an average amount of ocean cooling -- about 1.8
degrees Fahrenheit (1 degree C) -- relative to the last 30 years for
which data is available.
His forecast uses satellite measurements of the amount of sunlight
reflected back into space to calculate dust levels over the area where
hurricanes form.
"It gives us a sense of the total amount of dust over this one area of
the tropical Atlantic," Evan said." "We think there is a strong link
between dust and the formation of hurricanes and their intensification."
Evan's research has indicated that dust clouds, which can be as big as
the continental United States and spread as far as the Caribbean and
Central America, can cool the Atlantic from 1 to 2 degrees F (0.56-1.12
degrees C) during the summer.
Such a small difference can make a large difference in the number and
intensity of hurricanes that form.
Interest in African dust rose after the disastrous 2004 and 2005
hurricane seasons, when dust levels were low.
Four powerful storms hit Florida in 2004, while 2005 shattered records
with 28 storms, including Hurricane Katrina, which caused $80 billion in
damage on the U.S. Gulf Coast.
"We expect to see a lot more dust this year than we saw in 2004 and
2005," Evan said. "On average that could lower the ocean temperature not
even half a degree Celsius, maybe half a degree Fahrenheit. But that's a
huge change in energy."
Researchers think the hot, dry clouds of dust may interfere with
hurricanes by increasing wind shear, a change in wind speeds at
different altitudes that can rip apart cyclones. They also inject dry
air into the storms, which thrive on moisture.
Evan said he can predict African dust storm activity about eight months
in advance.
Research into dust storms and their impact on cyclones is relatively new
and hurricane forecasters have been reluctant to incorporate it into
seasonal predictions. But Evan said leading researchers are increasingly
looking at it.
The University of Wisconsin planned to issue a forecast in May, before
the June 1 start of the six-month Atlantic season, and update it in the
first week of June, July and August. (Editing by Michael Christie and
Alan Elsner)