NASA Provides Insight to Understanding Hurricanes
IT SEEMS THAT humans have been obsessed with understanding, predicting,
controlling and influencing the weather. Exploring the atmosphere
through its space program, NASA is a key player in showing that
weather prediction is a science with many life-saving and cost-saving
With an aim to better understand and improve ground-based predictions
of hurricanes, two specially equipped NASA aircrafta converted
spy plane and a refitted jetlinertook weather researchers
on a historic ride into the eye of Hurricane Bonnie in August 1998.
The intent of the researchers was to collect high-altitude information
about Atlantic hurricanes and tropical storms for more insight into
hurricane structure, dynamics and motion.
The Birth of a Hurricane
Sunlight heats the ocean. Water evaporates, rises and forms rain,
surrendering its heat to the air and accelerating the rise. Air
flows in on the surface to replace rising air, barometric pressure
drops and air masses slowly start circling.
The tropical depression becomes a tropical storm, winds grow steadily
until they pass the 110-kilometer-per-hour (km/h), or 60-knot, mark
and keep rising to 368 km/h (200 knots) or more. A hurricane is
The pattern repeated itself as the 1998 hurricane season in the
Atlantic Ocean began in mid-August. This year was different, though.
For the first time since the 1950s, research scientists looked at
the upper levels of the storms, not just the middle and lower altitudes
that are braved by hurricane hunter teams.
Why Hurricanes Have More Impact Today
It all comes down to thermodynamics, the physics of heat. Water
absorbs energy from the air or sunlight when it goes from sea surface
to vapor, and it surrenders energy to the air when it turns vapor
to rain drops.
Where the energy changes hands is what powers the hurricane, but
hurricanes are no more powerful than before. There are more people
living in coastal regions than ever before, and they have built
more homes and businesses for hurricanes to destroy. Therefore,
the need to understand the mechanics of hurricanes increases each
year as human populations grow in coastal areas.
Cutting-Edge NASA Research Could Save Lives and Money
Specially equipped NASA aircraft have taken to the skiescollecting
high-altitude information about Atlantic hurricanes and tropical
stormsas part of the third Convection and Moisture Experiment
(CAMEX-3). This mission may increase warning time, saving lives
and property, and decrease the size of evacuation areas, thus saving
National Oceanic and Atmospheric Administration (NOAA) officials
estimate that improved forecasting can be worth millions of dollars
per mile. That is, every inch of coastline that does not have to
be alerted avoids a million dollars in lost economic productivity.
Until a hurricane's power is more understood, forecasters practice
"overwarning" rather than risk a potential sudden "hit"
that catches people off guard.
CAMEX-3, designed to study the factors involved in how strong
a hurricane grows, is an interagency project to measure hurricane
dynamics at high altitudea method never before employed over
Atlantic storms. It operates out of Patrick Air Force Base in Florida.
The CAMEX-3 study uses NASA's converted DC-8 and ER-2 high-altitude
research aircraft in conjunction with NOAA's WP-3D Orion hurricane
hunter and various other instruments. It also uses data from weather
satellites and has timed its flights to coincide with observations
by the Tropical Rainfall Measuring Mission (TRMM) satellite.
"This is a significant achievement for this hurricane study,"
said CAMEX-3 project scientist Robbie Hood, mission scientist from
NASA's Global Hydrology and Climate Center at Marshall Space Flight
Center in Huntsville, Alabama. "We achieved our number one
objective, that we could accomplish the tricky maneuver of placing
all three NASA and NOAA aircraft in the study of the structure of
the same storm at the same time.
"A lot of these instruments either have versions flying on
satellites now or are prototypes for new satellites. We're bringing
NASA technology to the picture, satellite and remote sensing technology
in particular, and we're trying to give the hurricane research community
data that they don't have, data at high altitude where their aircraft
"The big thing is that we're bringing space flight technology
to bear," Hood said. "We can bring NASA technology to
an experiment and to help save lives in the future.
"The hurricane community has made great strides in making
more accurate forecasts and tracking," Hood said. "But
how intense that hurricane's going to be when it hits the shorelineor
why some storms die out and others just keep going and goingis
the important factor.
"This is part of ongoing research that NASA is conducting
to study the whole Earth and its atmosphere," Hood explained,
"but our real goal is to provide data that could be used eventually
to save lives."
Eye to Eye and Bonnie Winks
Hurricane Bonnie formed in the Atlantic Ocean in mid-August. On
August 23 and 24, teams of weather researchers went on a historic
first ride through and over Hurricane Bonnie's eyethe central,
open structure that is the focus of a hurricane's power and motionas
she churned in the Atlantic near the Bahama Islands. And, while
looking Bonnie in the eye, she winked.
Finally, on August 26, the team probed Bonnie as it hit the North
Carolina shore. The jetliner, flying at 11 km (37,000 feet), was
joined at the storm by a NASA ER-2 jet overhead at 19.8 km (65,000
feet) and a NOAA WP-3D Orion turboprop at 4.6 km (15,000 feet) for
a 7-hour mission. Bonnie did more than cooperate, veering toward
the Outer Banks of North Carolina at the last moment, and even posing
"We were afraid we were going to miss it," Hood said.
"But once we got there it was like it stopped to wait on us.
We noticed while we were flying through it, the center of the eye
was not moving that much, and for the last part of the flight it
was pretty much sitting still.
"This thing was just sitting here, just waiting on us. I
don't know if we'll ever be able to catch another one that perfectly."
During the Bonnie study, two co-existing eye walls were explored.
The team had excellent coordination in having one NOAA WP-3D Orion
on the first eye wall flight, and both Orions plus an Air Force
WC-130 Hercules were on the second eye wall penetration, for a total
of five aircraft. It was during the second eye wall flight that
Bonnie pulled yet another surprisesnow in August. "Right
along the eye wall this big dome cloud had come up, and it was shooting
ice crystals or snow up, and it was falling on top of the DC-8,"
Compelling images of a 59,000-foot storm cloud towering from Bonnie's
eye wall were obtained by the TRMM, offering some valuable information
to researchers. By comparison, the highest mountain in the world
is 29,000 feet, and the average commercial jet flies at barely one-half
the height of Bonnie's cloud tops.
Another impressive step was taken when NASA researchers gave Bonnie
some eye drops. Ten small tubes containing miniature weather stations
were dropped into Bonnie's shifting eye to check her vital signs,
wind speeds, barometric pressure and humidity levels. The tiny weather
stations dropped into the middle of the eye verified the readings
the DC-8 remote-sensing instruments were reading at 11 km (37,000
Success at the Halfway Mark
Although the scientists are halfway through the flight campaign,
they have hardly begun the important work of CAMEX-3: analyzing
the data. And they have plenty. "This experiment is going to
produce a ton of papers," Hood said.
A campaign to make the most extensive set of hurricane measurements
is already a phenomenal success, even though it is only halfway
through its flight time. "The Bonnie data set is just incredible,"
While hurricanes have been probed by aircraft since the 1940s
and monitored by satellites since the 1960s, this was the first
coordinated campaign to measure a hurricane's growth with aircraft
at low, medium and high altitudes. "We're going to push real
hard to get the data on-line as soon as possible," Hood said.
Browse or summary versions of the data will be available in 3 months,
and the first complete data sets will be available starting in 6
The hurricane study is part of NASA's Earth Science Enterprise.
Its purpose is to better understand the total Earth system and the
effects of natural and human-induced changes in the global environment.
For more information, contact Karen Kafton at the National Technology
Call: 800/678-9882, E-mail: firstname.lastname@example.org
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