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| [PHOTO: Joe Hall/Flickr/CC BY 2.0] |
Washington: A new NASA-funded prototype system developed by the National
Center for Atmospheric Research (NCAR) of Boulder, Colo., now is providing
weather forecasts that can help flights avoid major storms as they travel over
remote ocean regions. The eight-hour forecasts of potentially dangerous
atmospheric conditions are designed for pilots, air traffic controllers and
others involved in transoceanic flights.
The NCAR-based system
combines satellite data and computer weather models to produce maps of storms
over much of the world's oceans. The system is based on products that NCAR has
developed to alert pilots and air traffic controllers about storms and related
hazards, such as turbulence and lightning, over the continental United States.
Development of the forecasts was spurred in part by the 2009 crash of Air
France Flight 447, which encountered a complex of thunderstorms over the
Atlantic Ocean.
The system was funded
by NASA's Applied Sciences Program, which supports efforts to discover and
demonstrate innovative and practical uses of NASA Earth science and satellite
observations. NCAR worked with the Massachusetts Institute of Technology's
Lincoln Laboratory, the Naval Research Laboratory, and the University of
Wisconsin-Madison to create the system.
"These new
forecasts can help fill an important gap in our aviation system," said
NCAR's Cathy Kessinger, lead researcher on the project. "Pilots have had
limited information about atmospheric conditions as they fly over the ocean,
where conditions can be severe. By providing them with a picture of where
significant storms will be during an eight-hour period, the system can
contribute to both the safety and comfort of passengers on flights."
The forecasts, which
continue to be tested and modified, cover most of the Atlantic and Pacific
oceans, where NCAR has real-time access to geostationary satellite data. The
forecasts are updated every three hours.
Pilots of
transoceanic flights currently get preflight briefings and, in certain cases
involving especially intense storms, in-flight weather updates every four
hours. They also have onboard radar, but that information is of limited value
for strategic flight planning while en route.
"Turbulence is
the leading cause of injuries in commercial aviation," said John Haynes,
Applied Sciences Program manager at NASA Headquarters in Washington. "This
prototype system is of crucial importance to pilots and is another
demonstration of the practical benefit of NASA's Earth observations."
Pinpointing
turbulence associated with storms over the oceans is far more challenging than
it is over land because geostationary satellites, unlike ground-based radar, cannot
see within the clouds. Thunderstorms may develop quickly and move rapidly,
rendering the briefings and weather updates obsolete. Onboard radars lack the
power to see long distances or through dense clouds.
As a result, pilots
often must choose between detouring hundreds of miles around potentially stormy
areas or flying directly through a region that may or may not contain intense
weather. Storms may be associated with hazardous windshear and icing conditions
in addition to lightning, hail and potentially severe turbulence.
To create the
forecasts, Kessinger and her colleagues first turned to geostationary satellite
measurements to identify regions of the atmosphere that met two conditions:
particularly high cloud tops and water vapor at high altitudes. These two
conditions are a sign of powerful storms and strong updrafts that can buffet an
aircraft. The scientists next used fuzzy logic and data fusion techniques to
home in on storms of particular concern, and applied object tracking techniques
and simulations of wind fields to predict storm locations at hourly intervals
out to eight hours.
Researchers verified
the forecasts using a variety of data from NASA Earth observations, including
the Tropical Rainfall Measuring Mission (TRMM) satellite.
"These advanced
techniques enable us to inform pilots about the potential for violent
downdrafts and turbulence, even over the middle of the ocean where we don't
have land-based radar or other tools to observe storms in detail,"
Kessinger said.