Hurricane team probes ahead of Earl

Francis may be forming
in Caribbean

Sept. 4, 1998: (this is the 14th 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.)

Hurricane Earl drew in the researchers from the CAMEX and TEFLUN teams even as the storm was driving away the last tourists of summer.

Four aircraft probed and measured the weather ahead of Earl on Wednesday as it grew from a Category 1 to Category 2 hurricane and crossed the Gulf Shores into the Florida panhandle.

NASA's ER-2 and DC-8 and the University of North Dakota's Citation took off at 2 p.m. EDT to sample the rainfall intensities right before landfall. This storm, which was very disorganized, was upgraded from a tropical storm to a Category 1 hurricane status just a few hours before takeoff. By landing time Earl had been upgrade to a Category 2 hurricane.

In collaboration with NOAA, researchers from the University of Alabama in Huntsville researchers were positioned at the Tallahassee Airport to collect wind profile and surface observations while Texas Tech University investigators collected high resolution wind tower measurements just west of Panama City. Although the UAH team is not a part of the CAMEX-3 campaign, their data will complement the airborne studies of Earl.

Right: A color image from the NOAA-12 weather satellite's Advanced Very-High Resolution Radiometer shows Hurricane Earl as it moves across the Southeastern United States today at 6:58 a.m. (1158 UT). This image was produced by the Ocean Remote Sensing Group at The Johns Hopkins University's Applied Physics Laboratory. (Links to 823x950-pixel, 424-KB JPG.)

The aircraft are being used by a national team of scientists in the Convection and Moisture Experiment (CAMEX-3) to study hurricane growth, and the Texas and Florida Underflight (TEFLUN) experiment to validate measurements by the Tropical Rainfall Measuring Mission (TRMM). The experiment team comprises researchers from NASA, the National Oceanic and Atmospheric Administration, and universities.

Several flights have served the needs of both campaigns. The CAMEX team had a phenomenally successful series of flights studying Hurricanes Bonnie, Danielle and, now, Earl.

On Wednesday's flights, the aircraft were set up on north-south lines in the Gulf of Mexico between Tampa and Tallahassee, Fla. Light rain was observed on these lines.

Next, the line was shifted west toward Tallahassee. Moderate to heavy rainfall was observed on this line. A NOAA WP-3D Orion aircraft passed through the area to study the wind field and storm surge conditions of the landfalling hurricane. The Hurricane Hunters of the USAF 53rd Weather Reconnaissance Squadron also flew through Earl Wednesday to monitor its wind speeds, barometric pressure and eye location

Sign up for our EXPRESS SCIENCE NEWS delivery

After flying along these additional north-south lines, the aircraft shifted back to the original line to sample more rainfall. After these maneuvers were completed, then the DC-8 was asked to perform a spiraling maneuver down to 14,000 ft to sample the microphysics of the rain and to perform a passive microwave study of the rain at various heights. The DC-8 then returned to Patrick AFB, Fla., the CAMEX staging area, to complete a 6-hour mission. The ER-2 landed approximately 30 minutes later.

Thursday was a "no fly day" for the DC-8 and ER-2.

Hurricane Earl continues to be the major player in today's forecast for east central Florida, according to CAMEX forecaster Jeff Halverson. Earl has assumed a largely extratropical character with a pronounced synoptic-scale dry intrusion entering from the west-southwest, rain skewed largely to the northeast of center, lack of a well-defined center or eye, and a pronounced convective rain band draped from northeast to southwest over central Florida.

For the next two days, the outlook will be for widespread thunderstorms to continue. If Earl tracks to the north, the large-scale convergence over the peninsula should relax and allow the sea breezes to assume a greater degree of influence. Dry air aloft could still enhance the potential for locally strong downdrafts in some of the cells.

And over the next several days, the models track Earl northeastward along the Eastern Seaboard. A new area of convective activity, located over the central Caribbean, shows some signs of consolidation and could become a tropical depression within 24 hours. The feature is drifting west at about 15 mph. We'll have to watch this for the possibility of a Francis in the near future.

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  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. Includes listing of August flights and aircraft and spacecraft used in CAMEX-3. September 2: Bonnie Cuts a Towering Figure Satellite radar shows mountainous cloud chimney September 4: Hurricane team studies Earl Four aircraft probe storm (this story) 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. A midterm story (Aug. 31, 1998) reviews the first month of operations and the windfall of data.

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.

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.