"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
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.
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.