September 1, 1998
By comparison, the highest mountain in the world, Mt. Everest, is 29,000 feet and the average commercial jet flies at barely one-half the height of Bonnie's cloud tops.
"It looks like a skyscraper in the clouds," said Dr. Christian Kummerow, TRMM Project Scientist at NASA's Goddard Space Flight Center, Greenbelt, MD. "This is the first time that TRMM's precipitation radar has seen a structure of this type in a hurricane approaching the U.S. East coast."
"Clouds this tall are rarely observed in the core of Atlantic hurricanes," said Dr. Bob Simpson, former Director of the National Hurricane Center in Miami and the National Hurricane Research Project. "This huge cloud probably happened because, at the time the data was collected, Bonnie was moving very slowly. The lack of movement kept funneling warm moist air into the upper atmosphere, thus raising the entire height of the tropopause, which is normally at around 45-52,000 feet. The tropopause marks the upper limits of Earth's densest layer of atmosphere.
"The vast amount of warm, moist air being raised high into the atmosphere, and the subsequent release of latent energy as this tropical airmass condensed into rain drops, is thought to be the precursor of hurricane intensification, which was observed in Bonnie in the 24 to 48 hours after these data were collected," Simpson said.
Many scientists believe that towering cloud structures, such as the one observed by TRMM, are probably a precursor to hurricane intensification. This was the situation with Hurricane Bonnie, whose central pressure dropped from 977 millibars to 957 millibars in the subsequent 24 hours. Lower air pressure is associated with higher wind speeds and overall storm strengthening.
"TRMM has flown over 100 tropical cyclones since its launch in November of 1997," said Kummerow. "This enormously enhances our database of cloud structures within tropical storms during their growth and decay phases. It also greatly improves the more restricted observations we have obtained from aircraft radar and allows for the systematic study of this hurricane behavior which appears to precede their intensification."
As the height of the hurricane season approaches, TRMM scientists are looking forward to the continuing analysis of Atlantic hurricanes.
TRMM was launched November 27, 1997, from the Japanese Space Center, Tanegashima, Japan, and is a joint United States and Japanese mission, the first dedicated to measuring tropical and subtropical rainfall through microwave and visible infrared sensors, including the first spaceborne rain radar.
The TRMM spacecraft fills an enormous void in the ability to measure world-wide precipitation because so little of the planet is covered by ground-based radars. Presently, only two percent of the area covered by TRMM is covered by ground-based radars or surface rain gauges. By studying rainfall regionally and globally, and the difference in ocean and land-based storms, TRMM is providing scientists the most detailed information to date on the processes of these powerful storms, leading to new insights on how they affect global climate patterns.
The TRMM mission is part of NASA's Earth Science Enterprise, a long-term, coordinated research effort to study the total Earth system and the effects of natural and human-induced changes on the global environment.
More information about the TRMM project is available at:
TSE - THE SPACE EXPERIENCE
The NASA scientist said, however, the seven-hour flight she and a group of 35 NASA weather researchers took differed little from a ride on a commercial airliner.
"It wasn't any worse than flying into Atlanta. A couple of times ... it got kind of bumpy," the researcher said of her maiden flight into a Category 3 hurricane. "The pilot even turned off the seat belt signs."
The chase on a modified DC-8 airliner is part of a month-long attempt to create a computer model for tracking future tropical storms.
NASA's office of Earth Science Studies put the expedition together and enlisted the aid of at least three other government agencies, an orbiting satellite and scientists from eight universities.
"This will be the most comprehensive hurricane study to date," said Dave Steitz, a senior NASA spokesman at Patrick Air Force Base, the home base for the mission.
The scientists on the DC-8 and a pilot flying along in an ER-2, a former U-2 spy plane equipped with specialized Doppler radar, caught up with Bonnie east of the Bahamas. It's just one of several flights they plan to make into the storm.
Machines on both planes collected reams of data throughout the four passes through the hurricane's eye.
A NOAA plane flying below the DC-8 helped line up the plane as it measured winds, temperatures and air pressures for the creation of a three-dimensional computer model to be used in forecasting such storms in the future.
"The idea is to measure those qualities accurately and see if the models are correct," said Stuart Bowen, an atmospheric research specialist.
"The models make the predictions, we want to make sure the information's correct."
The pilots and scientists on the DC-8 had a simpler reaction to the storm with 115 mph winds. Hurricane Bonnie is very cloudy.
"It was hard to see the eye of the hurricane because of the clouds," said Hood, the lead scientist coordinating the flight for NASA.
The equipment on board did show that the eye of the storm was starting to change its formation, something several scientists didn't expect. Otherwise, the ride wasn't too surprising.
"We wouldn't have spilled coffee on this flight," said Ed Zister, a Texas A&M University researcher with extensive experience flying into hurricanes.
He attributed the smooth ride to the DC-8's altitude of 35,000 feet. Flying is much more dangerous farther down into the storm, he said.
Parallel to the DC-8 at an altitude of 65,000 feet was the refitted U-2 plane, best known for its spying capabilities during the Cold War.
The pilot of the white ER-2 used specialized Doppler radar to measure atmospheric conditions created by Hurricane Bonnie while a satellite gauged the moisture surrounding the storm.
ER-2 Pilot Jan Nystrom said it took him about 30 minutes to pass over the storm.
"It's pretty extensive," said Nystrom, who also flew above a Pacific typhoon in 1993.
The U.S. Air Force also guided two C-135 airplanes alongside the storm at lower altitudes to assist in gathering information while NOAA flew a P-3 Orion aircraft out of Miami as part of its routine tracking, Steitz said.
The NASA program is expected to cost taxpayers up to $3 million, Steitz said.
"It costs about $2 million a mile to evacuate. Using this information we can better predict where a hurricane will go," Steitz said. "If this works this can save tons of money and hopefully lives."
Sunday's flight likely will be followed up with another one today. NASA expected between eight and 10 storms this hurricane season.
On the Web:
To see data from the Patrick Air Force Base mission, go to Internet site http://www1.msfc.nasa.gov/NEWSROOM
NASA, NOAAA team seeks secret of hurricane's power
NASA Headquarters, Washington, DC
Marshall Space Flight Center, Huntsville, AL
August 12, 1998
The Convection and Moisture Experiment (CAMEX) mission is scheduled for August and September. Results from the mission may increase warning time -- saving lives and property -- and decrease the size of evacuation areas -- saving money -- while giving scientists a better understanding of these dramatic weather phenomena. CAMEX will yield high-resolution spatial and temperature information on hurricane structure, dynamics and motion, leading to improved hurricane prediction. Results also will be used to validate existing measurements from the Tropical Rainfall Measuring Mission of hurricanes and tropical storms and to develop algorithms for future Earth science missions.
Led by the Atmospheric Dynamics and Remote Sensing program at NASA Headquarters, Washington, DC, the experiment unites eight NASA centers, other government weather researchers and the university community for a coordinated, multi-agency and - university Atlantic hurricane and tropical storm study.
"We only know what goes on in the bottom half of a hurricane -- from sea level to 27,000 feet," said Robbie Hood of the Global Hydrology and Climate Center at NASA's Marshall Space Flight Center, Huntsville, AL. "With all of the agencies and the university community working together, we now can learn about these storms from top to bottom -- and hopefully improve hurricane prediction."
When a hurricane or tropical storm erupts in the Atlantic, a NASA Dryden Flight Research Center DC-8 -- equipped with instruments to measure the storm's structure, environment and changes in intensity and tracking -- will fly into the storm at 35,000-40,000 feet.
At the same time, a specially equipped Dryden ER-2 -- a high- altitude research plane -- will soar above the storm at 65,000 feet. The high-flying plane will measure the storm's structure and the surrounding atmosphere that steers the storm's movement.
On the ground, the storm research team will launch weather balloons and monitor land-based sensors to validate the high- altitude measurements taken by instruments aboard the planes.
Hood and her team plan to fly the NASA planes in conjunction with scheduled storm flights of the National Oceanic and Atmospheric Administration (NOAA) that will take off from MacDill Air Force Base, Tampa, FL, and the "Hurricane Hunters" -- the U.S. Air Force's 53rd Weather Reconnaissance Squadron from Keesler Air Force Base, MS.
The Air Force's Hurricane Hunters and NOAA routinely fly into tropical storms and hurricanes to determine the location, motion, strength and size of the storm. The information that the two organizations gather is used to predict the potential strength and size of the storm as well as landfall.
In addition to providing Doppler radars on each research plane, NASA for the first time will bring state-of-the-art airborne instruments to measure moisture and wind fields around the hurricanes under observation.
NOAA flies a WP-3 "Orion" -- a four engine turboprop plane -- into storms at altitudes below 27,000 feet. And the Hurricane Hunters fly a WC-130 "Hercules" -- a four-engine turboprop aircraft -- at 5,000-10,000 feet.
"We will analyze the high-altitude storm information within the context of more traditional low-level aircraft observations, and satellite and ground-based radar observations," said Hood. "This new information should provide insight to hurricane modelers -- forecasters who continually strive to improve hurricane predictions."
Scientific instruments provided by Marshall to be flown on the Dryden aircraft will be augmented by instruments from NASA's Goddard Space Flight Center, Greenbelt, MD; Jet Propulsion Laboratory, Pasadena, CA; Langley Research Center, Hampton, VA; and Ames Research Center, Moffett Field, CA.
The hurricane study is part of NASA's Earth Science enterprise to better understand the total Earth system and the effects of natural and human-induced changes on the global environment.