Eye-to-eye, and Bonnie winks

NASA/NOAA team makes first sortie into hurricane

Aug. 24, 1998: (This is the eighth 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 converted DC-8 jet airliner, outfitted as a remote sensing laboratory, took weather researchers on an historic ride Sunday into the eye of Hurricane Bonnie as she churned in the Atlantic near the Bahama Islands.

And while looking Bonnie in the eye, she winked.

Right: Combined visible (white) and water vapor (blue) images of North America as seen by GOES-8. Current images are available from the Global Hydrology and Climate Center's interactive viewer.

Ocean waves, whipped by Bonnie to 2.4 to 3.6 meters (8-12 ft) high, crashed ashore a few hundred meters from the runway at Patrick Air Force Base, Fla., where a DC-8 prepared for the first-ever NASA jet flight into the eye of an Atlantic hurricane on Sunday afternoon.

The jetliner, flying at 11 km (37,000 ft), was joined at the storm by a NASA ER-2 jet overhead at 19.8 km (65,000 ft), and a NOAA WP-3D Orion turboprop 4.6 km (15,000 ft). The NASA planes took off at 1:34 p.m. EDT on their seven-hour mission.

Here's looking at you, Bonnie NASA researchers took the first high-altitude over-the-top images of a hurricane Sunday when a NASA ER-2 aircraft overflew Hurricane Bonnie at 19.8 km (65,000 ft.; depicted at right). Four simultaneous microwave emission images of Hurricane Bonnie's eye, eyewall, sea surface, rain, and ice cloud crystals were recorded by the Advanced Microwave Precipitation Radiometer aboard the ER-2. A heavy rain band associated with the eyewall is clearly seen on the first image read by the instrument at a (10 GHz) frequency. The second (19 GHz) and third (37 GHz) images show rain and the sharp eyewall boundary. The fourth image (85.5 GHz) shows the presence of ice particles associated with the heavy rain band from the ocean surface to cloud tops at about 12.2 km (40,000 ft). Robbie Hood, with NASA's Marshall Space Flight Center in Huntsville, Ala., is the principal investigator for the experiment, and the mission scientist for the current NASA/NOAA investigation of Atlantic hurricanes. (link to 600x700-pixel, 77KB GIF, left and 700x600-pixel, 13KB GIF, right.) Credits: NASA/Marshall Space Flight Center.

"This is a significant achievement for this hurricane study," said Robbie Hood, mission scientist from NASA's Global Hydrology and Climate Center in Huntsville, Ala. "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."

The research program, called CAMEX-3, is a combined study effort including eight NASA Centers, NOAA, and a contingent of scientists from universities across the nation.

The aircraft performed four passes over the eye of the then-Category-2 storm, centered at 24.5 N, 71.4 W. Two of the passes were coordinated with a NOAA Orion passing below. Researchers could not see into the eye on two passes due to cloud cover, but recorded infrared images on each pass. The location of the eye was obtained by information passed along by scientists stationed at Patrick Air Force Base or aboard NOAA's Orion aircraft (like the one at right).

Once the aircraft reached the first hurricane of the 1998 season, the researchers encountered an unusual phenomenon: As the three aircraft flew in a stacked pattern, the eye wall turned from an oval to a oblong shape.

"This reshaping of the eye wall is characteristic of a hurricane that has stalled, and is preparing for a dramatic shift, either stronger or dying," said Dr. Ed Zipser, a weather expert from Texas A&M University.

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 ft).

Left: Dr. Jeffrey B. Halverson, of the NASA Goddard Space Flight Center, at the control station for the AVAPS (Airborne Vertical Aircraft Profiling System), NASA photo by Bill Ingalls; and Right: a version of dropsondes that use GPS technology to obtain very accurate wind measurements.

Dropsondes can measure temperature, horizontal wind speed, pressure, and humidity from altitudes as great as 24 km (15 mi) until landing. The sondes themselves are marvels of miniaturization, only 7 cm (2.75 in) in diameter and 40.6 cm (16 in) long, and weighing just 400 grams (less than a pound).

The RSS903 dropsonde used in CAMEX-3 and other campaigns were developed by the National Center for Atmospheric Research and the German Space Agency (DLR) jointly developed the new model to use advanced sensors and to incorporate Global Positioning Satellite (GPS) receivers. This last feature gives scientists precise measurements of the sonde's location - including altitude - as it is carried along by a storm. The sondes are deployed through a small launcher inside the DC-8 (left) (photo credit: Bill Ingalls/NASA).

Researchers are planning a second flight into the storm for today with a takeoff time of about 3:30 pm EDT for an eight-hour mission.

Weather forecast

With Bonnie pushing towards the coast, wrote forecaster R. Wohlman, the Eastern U.S. is dominated by an intense high-pressure region. This is causing any shortwaves from the west to ride far north into Minnesota, Michigan, and Illinois. Otherwise, Ohio valley through Colorado is clear. Remnants of Tropical Storm Charlie, which charged ashore in the Texas gulf region, have slowed, filled and dropped lots of much needed rain over the southern half of the dry Lone Star state. I would expect that this moisture, which shows up well in the satellite water vapor imagery, would continue its westward movement. A large region of cloudiness and associated moisture is moving thou the New England states, and is forecast to slowly drift off shore. If there is a weakness in the extensive anti-cyclonic area over the U.S., it might develop just offshore, between that high and the one located in the mid-Atlantic.

Meanwhile, Bonnie continues to develop nicely. Winds up to 167 km/h (90 knots) sustained observed in the morning reconnaissance, but much to the consternation of the forecasters at the National Hurricane Center, forward motion has all but ceased. At 11 a.m. (15Z), Bonnie was centered at 24.2N, 71.6W and forecast to start moving northwest, then gradually shift northward. Bonnie's recalcitrance is causing the various forecast programs, which had once seemed to be converging on a fairly uniform track, to appear to be diverging again.

Right: This is the University of Hawaii's prediction (made for the Federal Emergency Management Agency) of Bonnie's path.

24-48-hour forecast: The expectation is that Bonnie moves to the NW, but still beyond 300nm from Cocoa Beach, Fla.. Should be another good CAMEX-3 day. Watch for her to finally start to pick a direction and speed.

48-72-hour forecast: Bonnie should be almost adjacent to Cocoa Beach at midday. Forecasts bring it to about 55 km (300 nmi).

3- to 5-day forecast: As Bonnie disappears northward, keep an eye on the little one (TS4?) moving into the Gulf. If this has a longer run than did Charlie, there could be real damage on the Texas coast when it hits. Should see another TS approaching the leeward islands by the end of the period. KCOF to go back to easterly flow two days post Bonnie's passing, watch for RW/TS in the afternoons.

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 bingalls@hq.nasa.gov. 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 (this story) 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 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.

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.

Standard International Units: 

km - kilometer (1 km = 0.62 smi = 0.54 nmi) 

km/h - kilometers per hour 

English (or US) units: 

mi, or smi - miles (statute miles; 1 smi = 0.87 nmi = 1.61 km)
mph - (statute) miles per hour 

Nautical units: 

nmi - nautical miles (1 nmi = 1.15 smi= 1.85 km) 

kts - knots (nautical miles per hour) 

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.

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