Aug 31, 1998

Quite a Windfall

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Hurricane team completes the first half of unique science campaign

Aug. 31, 1998: (this is the twelfth in a series of stories covering the ongoing CAMEX mission to hunt hurricane data in a way not done since the 50s. Other stories are linked in below.)


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," said Robbie Hood, the mission scientist for the third Convection and Moisture Experiment (CAMEX-3). "Now we're really pumped. We'd like to work with Danielle as much as we did Bonnie so we can see the difference between two hurricanes. That will show us why is one big and why is one small."

While hurricanes have been probed by aircraft since the 1940s and monitored by satellites since the 1960s, this is the first coordinated campaign to measure a hurricane's growth with aircraft at low, medium, and high altitudes.

It brings to bear a range of modern instruments - including lasers, advanced radar, lightning sensors - on the aircraft and on board the Tropical Rainfall Measuring Mission (TRMM), launched in November 1997.

NOAA officials estimate that improved forecasting can be worth million dollars a mile. That is, every mile of coastline that does not have to be alerted avoids a million dollars in lost economic productivity. (Because of a hurricane's power, forecasters will over-warn rather than risk letting people be caught off guard.)

CAMEX-3 was designed to study the factors involved in how strong a hurricane grows. The campaign, directed by NASA's Global Hydrology and Climate Center in Huntsville, Alabama, involves two NASA aircraft - a converted spy plane and a refitted jetliner - plus hurricane researchers from the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Air Force's 53rd Weather Reconnaissance Squadron, the Hurricane Hunters. It also combines some activities with the NASA Texas-Florida Underflight (TEFLUN-B) campaign that measures a thunderstorm's environment and conditions from aircraft and the surface simultaneously as the TRMM satellite passes overhead.

Coming full circle with hurricanes

One of the ironies of flying through a hurricane is that it can be smooth sailing. At 7.6 to 10.6 km (25,000-35,000 ft), scientists aboard NASA's DC-8 Airborne Laboratory could have been on an ordinary flight.


"It was so smooth that it was hard to imagine what people on the ground were going through," said mission scientist Robbie Hood ( ). "I had really mixed emotions about that. We were happy to catch it, but then you always wonder what's happening to the people below."

Actually, Hood knows all too well.

Her first experience with a hurricane was at age 13 in 1969 when Hurricane Camille smashed through the Gulf Coast and claimed 256 lives. Hood was living in Picayune, Miss., 80 km (50 mi) inland.

"Hurricane Camille was such an intense storm that the eye was still well formed and came right over our house," Hood said. "It pretty much tore up the entire coastline, but even 50 miles inland it devastated that little town we were living in - a lot of houses were torn up and trees downed."

She also lived in Missouri in Tornado Alley, "So that's where I got my interest in hurricanes and severe weather."

Her interest was in remote sensing - observing with instruments aboard satellites and aircraft - and that work brought Hood full circle to the Global Hydrology and Climate Center in Huntsville, Al., where she develops instruments and methods to study storms by satellite.


Of course, the easy part is getting the hardware and people together. The hard part is waiting for nature to cooperate.


as seen by the Airborne Rain Mapping Radar (ARMAR) on DC-8, Aug. 23.


"I was worried before we ever left as to whether we would have a hurricane at all," Hood said, "would we get out there on time, how many times we could go through it."

Check below for the CAMEX-3 schedule to date, and a list of aircraft and satellites.


Then Hurricane Bonnie formed in the mid-Atlantic Ocean and for a while was headed right for Patrick Air Force Base, Fla., where the CAMEX team is based. For several days the team arrived at work with their suitcases, anticipating orders to evacuate to Warner Robbins AFB, Ga.

Bonnie did more than cooperate - it veered towards the Outer Banks of North Carolina at the last moment and even posed for pictures.


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"On Wednesday [Aug. 26] when we went out to study it when it was making landfall, we were afraid we were going to miss it," Hood explained. "And when we got up there, it was already at least an hour ahead of its forecast position. 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. It was just eerie - it was just waiting on us.

"This was just cosmic. There are three TRMM [satellite] overpasses, and we've got all these airplanes, and 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."

In all, the CAMEX-3 team made four sets of coordinated flights involving NASA, NOAA, and Air Force aircraft. The first set, on Aug. 21, was a synoptic flight, measuring conditions that would determine Bonnie's growth as it moved westward. On Aug. 23 and 24, the teams flew through and over the eye, the central, open structure that is the focus of a hurricane's motion and energy. Finally, on Aug. 26, the team probed Bonnie as it hit the North Carolina shore.


Gathering the data

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.

"Most of the instrumentation's been doing really well," she continued, "especially the landfall case. At one point we lowered our altitude on the DC-8 to fly between cloud layers. It was an excellent mission for MACAWS, the Multicenter Airborne Coherent Atmospheric Wind Sensor."

Above: The

during a test flight just before Bonnie formed. photo credit: Bill Ingalls/NASA


MACAWS aims at laser into the clear air and measures the light reflected back by aerosols in the atmosphere. Like measuring the speed of a star, the red shift - or blue shift - tells the speed of the aerosol relative to the aircraft. Subtracting the aircraft's speed yields the true wind speeds across wide, clear sections between the storm's cloud decks. Such measurements are difficult to obtain unless you fly right through every spot in the storm.

"MACAWS was seeing all kinds of wind structures" in the middle of Bonnie, Hood said. "I was talking with Dr. Jeff Rothermel [of NASA/Marshall Space Flight Center, the principal investigator] Thursday and he's really excited about the data set he collected."

The other laser instrument is the Lidar Atmospheric Sensing Experiment (LASE) from NASA's Langley Research Center. It measures moisture and aerosol content, crucial factors in how strong a storm will become.

"The LASE people had a pretty good mission, too. They wanted to sample the moisture of the inflow region as it's coming inside the storm. We think we captured that" when they flew in between the cloud decks at 7.6 km (25,000 ft.).

"Bonnie was just in the right place at the right time the whole time we were working it. My only regret is that I wish we could have worked it yesterday, too. We really thought it was going to go overland, and that it was going to die out."

Then the team rested, although they might have flown again on Aug. 27 had they known that Bonnie - unexpectedly - would veer back out to sea and pick up energy again.

"To have gotten one hurricane and worked it four times is just phenomenal to me," Hood said. "We still have about half of our flight hours to go, so we can work another one at least three or four times."

Some of that attention will go to Danielle, now expected to hook around to the north and not even make landfall. Danielle is more compact and less energetic than Bonnie. The CAMEX-3 team flew two missions over the weekend. On Saturday, the Citation II flew a convection study with a TRMM overflight. The DC-8 completed a successful vortex motion and evolution flight through Danielle and peppered Danielle with 40 dropsondes. On Sunday, DC-8 had another successful vortex motion and evolution inflow flight on Hurricane Danielle. Monday will be a no-fly day for the team, in preparation for flights on Tuesday.

During the Bonnie study, 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 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 surprise - snow 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," Hood explained.

"The eye wall was trying to redefine itself. Traditional theory is that you have an eye here, and the new eye wall is forming out here, and it will eventually squeeze in and overpower the original eye wall. If it has a greater wind speed than the original eye wall, if it moves in faster, it will increase the wind even more through conservation of momentum, and it makes the wind even more powerful.


What we saw, on all three days, was the traditional eye wall, and then this outer eye wall, and the wind speeds were greater in the outer eye wall, but it pretty much stayed in the same place. The inner eye wall was going through all kinds of fluctuations."

The team also noticed that the eye wall location radioed up by the NOAA Orion crews did not match the location that the DC-8 crew was observing.

"A lot of times we found the eye at our altitude was displaced, one way or the other from what was seen at the lower altitudes. What I was amazed about was how fast it was doing that. We would go out of the eye and come back a half an hour later and the thing would be shifted this way or that way."

Right, Above:

of part of Bonnie as seen by the Multispectral Atmospheric Mapping Sensor (MAMS) on ER-2, Aug. 23.



"For me all this is brand new, because I've never flown through a hurricane. But people like Ed Zipser, who know a lot more about hurricanes, were a lot more surprised by what we were seeing."

More surprises my lie ahead. With only half of the flight time used, the CAMEX-3 team is planning how they will investigate Danielle, and whether to hoard some of the hours for the hurricanes that may form later. The CAMEX-3 campaign is scheduled to run through Sept. 23.

Left: Danielle, as seen by the NASA/Goddard SeaWIFS instrument, with the ground track of the DC-8 Airborne Laboratory overlaid. Hurricane Bonnie, at the top right of the image, is moving northeast across the North Atlantic Ocean. The black section to the right is where data are unavailable because of the satellite's own path and scnn pattern. (links to





CAMEX-3/TEFLUN-B flight activities
5 ER-2 arrives at Patrick Air Force Base
6 No-fly day
7 No-fly day
8 Shakedown over Andros Island Ground Station. The convective thunderstorm was exactly below the ER-2 flight track as predicted and we should have some good data from the flight.
9 No-fly day
10 DC-8 flies from Dryden Flight Research Center to Patrick AFB
11 No-fly day
12 No-fly day
13 TEFLUN B: Deep convection measurements over Melbourne, Fla., area. The TEFLUN-B ground coordination flight seems to be a large success. We had all three aircraft in stacked formation, on coordinated lines, through an active storm, instruments working well, with a TRMM satellite overpass.
14 No-fly day
15 TEFLUN B: Deep convection measurements over central Florida
16 No-fly day
17 No-fly day
18 No-fly day
19 No-fly day
20 TEFLUN B: Convection east of Cape Canaveral. Today's TEFLUN-B mission was highly successful. The ER-2 was canceled due to high cross winds. The DC-8 and UND Citation accomplished major goals in the stratiform rain environment while the TRMM satellite passed overhead. The NASA aircraft are on alert for a CAMEX-3, tropical storm Bonnie, flight tomorrow. The UND Citation is on alert for a possible TEFLUN-B mission.
21 CAMEX-3: Tropical Storm Bonnie synoptic flow measurements. The ER-2 was canceled due to high winds. The DC-8 did fly a synoptic flow mission on tropical storm Bonnie. Everything seems to be a success. Patrick AFB is officially on a HURCON 4 alert. The AF Battle Staff will meet at 1000 tomorrow. We need to prepare to evacuate the base tomorrow If we are not forced to evacuate, tomorrow will be a no fly day. Stay tuned.
22 TEFLUN B: Citation II TEFLUN mission was successful today; the NASA DC-8 and ER-2 had no-fly day. Patrick AFB issued a HURCON 3 posted at 1300 EDT. Plans are to perform another Bonnie mission tomorrow with DC-8 and ER-2. If HURCON 2 is issued, we will have to evacuate the area immediately. The aircraft will be sent to Warner-Robbins AFB, Macon, GA.
23 CAMEX-3: Hurricane Bonnie eye wall #1. DC-8 and ER-2 made extremely successful flights over the eye wall of hurricane Bonnie in coordination with the NOAA aircraft. They both overflew the Andros Island site on the return from Bonnie. Monday we will make another flight over hurricane Bonnie, planning closer coordination with NOAA aircraft Flight tracks over the hurricane will be similar to the ones flown on Sunday.
24 CAMEX-3: Hurricane Bonnie eye wall #2. CAMEX bagged another highly successful overflight of Hurricane Bonnie in conjunction with the NOAA WP-3 aircraft. The aircraft will stand down Tuesday, Aug. 25.
25 No-fly day
26 CAMEX-3: Hurricane Bonnie landfall. Another extremely successful flight day. Both ER-2 and DC-8 overflew Bonnie as it made landfall. There were three TRMM overpasses during the flight with the earliest overpass almost directly over the eye wall. Both NOAA Orions also flew coordinated patterns with the NASA aircraft. Tomorrow will be a no fly day and Friday a tentative hard down day. We anticipate the earliest opportunity for a Hurricane Danielle flight on Saturday, 29 August.
27 TEFLUN B: UND Citation II had a successful flight studying convection over the S-POL site.
28 No-fly day
29 CAMEX-3: Vortex motion and evolution and moisture inflow measurements of Danielle by DC-8.
30 CAMEX-3: Vortex motion and evolution and moisture inflow measurements of Danielle by DC-8.
31 No-fly day


CAMEX-3/TEFLUN-B aircraft
ER-2: Cold War-era U-2 spy plane converted for Earth resources observations by NASA. The ER-2 used in CAMEX-3 is equipped with STARLINK (Satellite Telemetry and Return Link) for real-time data downlinks. Operated by NASA's Dryden Flight Research Center.
DC-8 Airborne Laboratory: 4-engine jetliner outfitted by NASA as an airborne laboratory. Operated by NASA's Dryden Flight Research Center.
Citation II: 2-engine executive jet outfitted by the Aerospace Sciences Department of the University of North Dakota with atmospheric instrumentation. Used mainly in TEFLUN-B studies.
WP-3D Orion: 4-engine turboprop, former U.S. Navy antisubmarine patrol plane (P-3) converted by NOAA for hurricane studies. Operated by NOAA Hurricane Research Division.
Gulfstream IV: 2-engine executive jet outfitted by the National Oceanic and Atmospheric Administration for hurricane studies. Operated by NOAA Hurricane Research Division.
WC-130 Hercules: 4-engine turboprop, U.S. Air Force cargo plane outfitted for hurricane studies. Operated by the 53rd Weather Reconnaissance Squadron.


CAMEX-3/TEFLUN-B satellites


GOES-8: Geostationary Operational Environmental Satellite; operated by NOAA.


NOAA: Polar-orbit weather satellites; operated by NOAA (also called Advanced Television Infrared Observational Satellites [TIROS]).


TRMM: Tropical Rainfall Measuring Mission; Japanese satellite carrying some NASA instruments, including mapping radar and a Lightning Imaging Sensor.


SeaStar: Commercial satellite, operated by Orbital Sciences Corp. under contract to NASA, carrying the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). Not a formal part of CAMEX-3, but its data are available to investigators.


Note: More details are available in the NASA press release describing CAMEX-3. Check back as hurricane season progresses. We will post science updates as the campaign develops.

PIX: High resolution scans of 35mm camera photos from the CAMEX-3 campaign are available from Public Affairs Office at NASA headquarters. Please call the NASA Headquarters Photo Department at 202-358-1900, or contact Bill Ingalls at


CAMEX Series Headlines

August 12: Overview CAMEX story , describes the program in detail.
August 13: CAMEX maiden flight , for calibration of TRMM satellite instruments
August 14: CAMEX test flights , CAMEX flies over tropical storm weather in successful calibration run
August 18: CAMEX aircraft make second flight with TRMM , second calibration run for TRMM
August 20: CAMEX may get first chance at a tropical storm , later this week 
August 21: Here comes Bonnie! , CAMEX scheduled to fly over T.S. Bonnie 
August 22: West by Northwest , CAMEX team may have to evacuate to Georgia 
August 24: Eye-to-eye, and Bonnie winks, CAMEX team makes first flight through eye 
August 25: Snow in August, Bonnie surprises the hurricane team 
August 26: Camera of many colors Hurricane hunters using advanced scanner to peer into storms  
August 28: Preparing for Danielle NASA team takes break as Bonnie fades away
August 31: Quite a Windfall Hurricane team completes first half of unique science campaign (this story)
September 2: Bonnie Cuts a Towering Figure
Satellite radar shows mountainous cloud chimney
September 4: Hurricane team studies Earl Four aircraft probe storm
September 10: NASA team awaits next hurricane
September 16: Hurricane season passing its prime
Thunderstorm studies continue as a new hurricane candidate wends its way from Africa.
September 18: Two new storms brewing for hurricane research team Scientists fly 4 out of 5 days, clear air sampled over the Bahamas, oceanic convection data collected east of Cape Canaveral
September 21:The last hurricane - CAMEX team wrapping up campaign with flights into Georges
September 23: Hurricane Georges puts on a light show - CAMEX team treated to purple sprites and weird lightning

NCAR has an extensive writeup on the GPS dropsondes used in CAMEX-3 and other atmospheric campaigns.

A new study - not related to CAMEX-3 - by the Arizona State University suggests a link between hurricanes in the northwest Atlantic and air pollution.



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CAMEX-3 - the third Convection and Moisture Experiment - is an interagency project to measure hurricane dynamics at high altitude, a method never employed before over Atlantic storms. From this, scientists hope to understand better how hurricanes are powered and to improve the tools they use to predict hurricane intensity.

An overview story (Aug. 12, 1998) describes the program in detail. The 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.

Measuring distance and speed: Because meteorology and aeronautics first used modified nautical charts, their data bases are in nautical miles and knots (nautical miles per hour). In these stories, we use Standard International ("metric") units first, and give more familiar measurements in English units and the original measurements in nautical units. Because of rounding and because the wind speeds originally are expressed in knots, km/h speeds to knots may be slightly different from the numbers in the story.

km - kilometer (1 km = 0.62 smi = 0.54 nmi) 
km/h - kilometers per hour 
mi, or smi - miles (statute miles; 1 smi = 0.87 nmi = 1.61 km)
mph - (statute) miles per hour 
nmi - nautical miles (1 nmi = 1.15 smi= 1.85 km) 
kts - knots (nautical miles per hour) 
Standard International Units: 
English (or US) units: 
Nautical units: 


Web Links
CAMEX-3 home page contains links to daily flight operations and instrument descriptions.
Lightning Imaging Sensor aboard the TRMM satellite observes lightning from above the clouds - and my lead to better warnings on the ground.
MACAWS uses the Doppler effect (red and blue shifts) to measure wind velocity.
SPARCLE is a Space Shuttle experiment set for 2001 to demonstrate laser wind measurement from space.


More web links 
  • More Space Science Headlines - NASA research on the web 
  • The Marshall Newsroom - more information on this and other news from the Marshall Space Flight Center 
  • NASA's Earth Science Enterprise Information on Earth Science missions, etc. 
  • Global Hydrology and Climate Center studies the global water cycle and its effect on climate. 
  • National Hurricane Center carries the latest tracking information on tropical storms and hurricanes. It also has lots of historical data and images, including hi-resolution copies of the pictures above of damage by Hurricane Andrew. 
  • The Public Use of Remote Sensing Data at Goddard Space Flight Center has high-resolution images of Fran (including the original of the image used in this story), Andrew, and other hurricanes and of other events seen from space.