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.
Image right: During hurricane season, thunderstorms form over Africa and travel west across the Atlantic, where some develop into tropical cyclones. This Meteosat-8 infrared image shows such thunderstorms. The NASA African Monsoon Multidisciplinary Analyses 2006 field campaign will study how winds and dust conditions from Africa influence the birth of hurricanes in the Atlantic. Image credit: NOAA/European Organisation for the Exploitation of Meteorological Satellites (Eumetsat)
+ Related animation + Browse version of image
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.
+ NASA's Hurricane Resource Page
+ Airborne Dual-frequency Precipitation Radar
+ Cloudsat Mission
+ Quikscat Mission
+ AIRS Mission
+ Wallops NAMMA Press Release
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
Carmeyia Gillis, National Oceanic and Atmospheric Administration, 301-763-8000, ext. 7163
Jana Goldman, National Oceanic and Atmospheric Administration, 301-713-2483, ext. 181.
The California Institute of Technology manages JPL for NASA.
Media contacts: Alan Buis 818-354-0474
Jet Propulsion Laboratory, Pasadena, Calif.
Erica Hupp/Dwayne Brown 202-358-1237/1726
NASA Headquarters, Washington