MEDIA RELATIONS OFFICE
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NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
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http://www.jpl.nasa.gov

Alan Buis 818-354-0474
Jet Propulsion Laboratory, Pasadena, Calif.

Erica Hupp/Dwayne Brown 202-358-1237/1726
NASA Headquarters, Washington

News Release: 2006-096 July 26, 2006

NASA Africa Mission Investigates Origin, Development of Hurricanes

Scientists from NASA, the National Oceanic and Atmospheric
Administration, universities and international agencies will
study how winds and dust conditions from Africa influence the
birth of hurricanes in the Atlantic Ocean.

The field campaign, called NASA African Monsoon Multidisciplinary
Analyses 2006, runs from Aug. 15 to mid-September in the Cape
Verde Islands, 563 kilometers (350 miles) off the coast of
Senegal in West Africa. This campaign is a component of a much
broader international project, called the African Monsoon
Multidisciplinary Analyses, aimed at improving the knowledge and
understanding of the West African Monsoon.

Researchers will use satellite data, weather station information,
computer models and aircraft to provide scientists with better
insight into all the conditions that enhance the development of
tropical cyclones, the general name given to tropical depressions,
storms and hurricanes. This research will help hurricane
forecasters better understand the behavior of these deadly storms.

"Scientists recognize the hurricane development process when
they see it, but our skill in forecasting which weak system will
intensify into a major cyclone is not great," said Dr. Edward
Zipser, mission chief scientist, of the University of Utah,
Salt Lake City. "That is why NASA and its partners place a high
priority on obtaining high-quality data for weak disturbances, as
well as those already showing signs of intensification."

For hurricanes to develop, specific environmental conditions
must be present: warm ocean water, high humidity and favorable
atmospheric and upward spiraling wind patterns off the ocean
surface. Atlantic hurricanes usually start as weak tropical
disturbances off the West African coast and intensify into
rotating storms with weak winds, called tropical depressions.
If the depressions reach wind speeds of at least 63 kilometers
(39 miles) per hour, they are classified as tropical storms.
Hurricanes have winds greater than 117 kilometers (73 miles)
per hour.

To study these environmental conditions, researchers will use
NASA's DC-8 research aircraft as a platform for advanced
atmospheric research instruments. Remote and on-site sensing
devices, including two from NASA's Jet Propulsion Laboratory,
Pasadena, Calif., will allow scientists to target specific
areas in developing storms. Sensors on board the aircraft will
measure cloud and particle sizes and shapes, wind speed and
direction, rainfall rates, atmospheric temperature, pressure,
and relative humidity. JPL's Airborne Dual-frequency
Precipitation Radar is a next-generation rain radar that will
be used to better characterize precipitation processes. JPL's
High-Altitude Monolithic Microwave Integrated Circuit Sounding
Radiometer measures temperature and moisture content in the
atmosphere.

The campaign will use extensive data from NASA's fleet of Earth
observing satellites, including the Tropical Rainfall Measurement
Mission, QuikScat, Aqua, and the recently-launched CloudSat and
Cloud-Aerosol Lidar and Infrared Pathfinder Satellite
Observations, or Calipso. These advanced satellites will
provide unprecedented views into the vertical structure of the
tropical systems, while the field observations will help validate
data from the new satellites. JPL manages QuikScat, CloudSat and
the Atmospheric Infrared Sounder (Airs) instrument on Aqua.

During the field campaign, scientists hope to get a better
understanding of the role of the Saharan Air Layer and how its
dry air, strong embedded winds and dust influence cyclone
development. The layer is a mass of very dry, often dusty air
that forms over the Sahara Desert during the late spring,
summer, and early fall and usually moves out over the
tropical Atlantic Ocean.

As part of looking at the Saharan Air Layer, scientists want
to better understand dust's effect on clouds. Some evidence
indicates that dust makes it more difficult for rain to form.
Cloud models need to account for any such effect, so
measurements of cloud-droplet concentrations and size in
clean ocean air and dusty air from the Sahara need to be made.


Researchers also will look at what happens to air currents as
they move from land to ocean waters. Information on clouds and
moisture, heat, air movement, and precipitation in an unstable
atmosphere will be collected, analyzed and then simulated in
computer models. Understanding hurricane formation requires
measurements from very small to large scales, from microscopic
dust and raindrops to cloud formations and air currents spanning
hundreds of kilometers.

More on NASA's hurricane research is at:

http://www.nasa.gov/hurricane .

More on Airborne Dual-frequency Precipitation Radar:

http://trmm.jpl.nasa.gov/apr.html ;

CloudSat: http://www.nasa.gov/cloudsat ;

QuikScat: http://winds.jpl.nasa.gov/missions/quikscat/index.cfm ;

Airs: http://www-airs.jpl.nasa.gov/ .

The California Institute of Technology manages JPL for
NASA.

Other media contacts: Ruth Marlaire, Ames Research Center,
Moffett Field, Calif., 650-604-4709;
Rob Gutro, Goddard Space Flight Center, Greenbelt, Md.,
301-286-4044;
Chris Rink, Langley Research Center, Hampton, Va., 757-864-6786;
Steve Roy, Marshall Space Flight Center, Huntsville, Ala.,
256-544-6535; National Oceanic and Atmospheric Administration,
Carmeyia Gillis, 301-763-8000, ext. 7163; and Jana Goldman,
301-713-2483, ext. 181.

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