Aug.
25, 1998: (This is the ninth 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.)
Weather researchers taking part in NASA's CAMEX-3 hurricane
study found Monday that Hurricane Bonnie is still not a classic
storm, and is full of surprises - including snow in the middle
of August.
An armada of five aircraft took part in the second flight
into Bonnie as the hurricane continued northwest at less than
16 km/h (10 mph). Joining the NASA ER-2 high-altitude jet and
the converted NASA DC-8 airliner, NOAA increased its study team
to two WP-3D Orion turboprop airplanes and the U.S. Air Force
added a C-130 Hercules cargo plane to measure the season's first
hurricane. The NASA airplanes left their staging point at Patrick
Air Force Base, Fla., for the eight-hour mission at 3:30 p.m.
EDT, returning at 11:30 p.m. EDT.
What looks like abstract art at right is a detailed microwave
image of water - as rain and as ice - distributed along a strip
40 by 160 km (25 x 100 mi) inside Hurricane Bonnie (click for
image showing four data strips
at different frequencies). It was made Sunday by the Advanced
Microwave Precipitation Radiometer (AMPR) aboard the high-altitude
ER-2. Every object emits a little bit of radiation; the frequency
depends on the temperature and other factors. AMPR is tuned to
microwaves - at 10.7, 19.35, 37.1, and 85.5 gigahertz (GHz) -
unique to water. By scanning the scene below the ER-2, AMPR produces
images of water distribution in the atmosphere. AMPR is similar
to instruments aboard polar-orbit weather satellites and the
Tropical Rainfall Measuring Mission (TRMM). In observing Bonnie,
AMPR shows convection and storm intensity, eye wall structures,
rain distribution. During landfall, it will be able to map changes
in convection and show the relationship of electrification to
signal storm intensity changes. More information on AMPR is available
on its page
at the CAMEX-3 web site and at the AMPR
home page. |
Click on the picture to go to an animated infrared view of Bonnie! |
Mission Scientist Robbie Hood from NASA's Marshall Space Flight
Center in Huntsville, Ala., stressed that the nation's weather
researchers will greatly benefit from the large body of information
being collected at one time at distinct levels of a single hurricane.
The ER-2 aircraft flew up to an altitude of 21 km (69,000
ft), the DC-8 at 10.6 km (35,000 ft), with the NOAA Orions at
4.6 and 1.5 km (15,000 and 5,000 ft), and the Air Force Hercules
in the storm at 3 km (10,000 ft). |
"We could all communicate and know what parts of the
storm we were studying, our timing was perfect," she said.
The collection of aircraft made six passes through the hurricane.
"The NOAA and Air Force aircraft really helped the study
because we had a better idea of what was happening below us,"
she added.
Bonnie
displayed a unique feature to ER-2 pilot Ken Broda from NASA's
Dryden Flight Research Center, Calif., who made his first ever
flight over a hurricane in the Monday mission.
Left:
A GOES-8 image this morning depicts Bonnie's strength by showing
cold areas (growing colder from blue to yellow to red) which
indicate where clouds are highest in the atmosphere.
"I saw a large, domed cloud that looked like a mini-hurricane
swirling out of the top of Bonnie about 70 miles (112 km) north
of the eye at about 55,000 feet (16.8 km)," Broda said.
"These storms are usually very symmetrical, but Bonnie
is nothing like what we would expect," said Texas A&M
University weather scientist Ed Zipser. While hurricanes normally
display a pattern of wind flow that pulls winds in at the base
of the hurricane, up through the eye, and out at the top of the
storm, Bonnie apparently doesn't work that way.
"We found winds coming into the hurricane from the southwest
at 40-50 knots (74-93 km/h) at our altitude, and winds and moisture
being pumped out of the chimney that Ken saw flowing to the Northwest.
As we flew to the boundary of the winds, the moisture blown out
through the chimney turned to snow and fell into the DC-8 flight
path - this was very spectacular," Zipser said. Instruments
also recorded wind shear along the wind flow boundary.
Evidence
remained of the possible restructuring of the hurricane center
as the eye remained lopsided on the east and north sides of the
storm. Just trying to locate the eye produced more of a bumpy
ride for the researchers Monday, according to DC-8 pilots Gordon
Fullerton (left) and Dick Ewers (right). In addition, DC-8 instruments
recorded 117 km/h (63-knot) winds at 10.6 km (35,000 feet), a
wind speed not considered usual, and an Orion recorded 222 km/h
(120-knot)winds on the northeast side of the storm, 93 km (50
nmi) from the center. (photo credit: Bill
Ingalls/NASA)
The researchers will not fly today, and are considering a
mid-day flight Wednesday in concert with NOAA as the hurricane
approaches a possible landfall.
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 (this story)
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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