August 12, 1998: (this is the first in a series of stories covering
the ongoing CAMEX mission to hunt hurricane data in a way not
done since the 50s. The complete series
of stories is linked in below.)
Sunlight heats the Eastern Atlantic
Ocean. Water evaporates, rises, and forms rain, surrendering
its heat to the air and accelerating the rise. Air flows in on
the surface to replace rising air, barometric pressure drops,
air masses slowly start circling.
The tropical depression becomes a tropical storm, winds grow
steadily until they pass the 110-km/h (60-knot) mark and keep
rising, perhaps 368 km/h (200 knots) or more.
A hurricane is born - the flags at the left are the
international maritime warning - and for the next few weeks,
it is the focal point for hundreds of meteorologists and disaster
management experts.
Top, right:
The current GOES-8 image of the North America. Click on the image
to go to the Global Hydrology and Climate Center's Interactive
Global Geostationary Weather Satellite Image Viewer and see
what's brewing.
The pattern is repeating now as the 1998 hurricane season
opens. This year will be different, though. For the first time
since the 1950s, research scientists will be looking at the upper
levels of the storms, not just the middle altitudes that are
braved by hurricane hunter teams.
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. (this story)
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
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. |
The third Convection
and Moisture Experiment (CAMEX-3) is under way with the arrival
at Patrick Air Force Base, Fla., south of Cape Canaveral, of
two NASA aircraft outfitted with a suite of instruments.
Left:
Hurricanes are among the most devastating natural phenomena,
as seen in this picture of damage caused by Andrew in 1992.
"This is part of ongoing research that NASA is conducting
to study the whole Earth and its atmosphere," said Robbie
Hood, the CAMEX-3 project scientist. "Our real goal is to
provide data that could be used eventually to save lives. We
can bring NASA technology to an experiment and to help save lives
in the future." |
![subscription image](https://webarchive.library.unt.edu/eot2008/20080916070339im_/http://science.nasa.gov/images/express_tiny.gif)
Sign up for
our EXPRESS SCIENCE NEWS delivery |
Hood, assigned to NASA's Marshall
Space Flight Center, works at the Global Hydrology and Climate
Center in Huntsville, Ala. For the next few weeks she will be
at Patrick AFB, directing operations with NASA's ER-2 and DC-8
aircraft and coordinating observations by scientists from NASA,
the National Oceanic and Atmospheric Administration, and several
universities.
Hurricanes are cyclonic storms whose power becomes greater
toward the center, almost like water swirling ever faster as
it goes down a drain. The winds are greatest at the core where
they shear away to leave a calm "eye" in the center.
(Typhoon is the name given cyclonic storms in the North Pacific
Ocean. Tornadoes sometimes are called cyclones, but they are
as different from hurricanes as a jazz dancer and a sumo wrestler.
)
On average, hurricanes are no more powerful than ever. But
more people live in coastal regions, and they have built more
homes and businesses for hurricanes to destroy. So, the need
to understand the mechanics of hurricanes increases each year
as human populations grow in coastal areas. |
CAMEX-3 aircraft carry several instruments
developed under the sponsorship of NASA/Marshall, including:
- Advanced Microwave Precipitation Radiometer (AMPR) aboard the ER-2. AMPR "listens" to the
rain. Actually, it measures how the rain absorbs normal microwave
emissions that the Earth always emits, like a person's body temperature.
AMPR can mimic microwave instruments aboard polar orbit weather
satellites, the Tropical Rainfall Measuring Mission (TRMM), and
a radiometer planned for the Earth Observing System. Hood is
also the principal investigator for AMPR.
Lightning
Instrument Package (LIP) aboard
the ER-2 and DC-8. LIP consists of probes that measure atmospheric
electricity conditions around the aircraft.
- Multispectral Atmospheric Mapping Sensor (MAMS) aboard the ER-2. MAMS
measures eight visible and near-infrared channels to map water
vapor content.
- Multicenter Airborne Coherent Atmospheric Wind Sensor
(MACAWS) aboard the DC-8 (right).
This is an eye-safe laser that measures wind speeds. The laser
scans fore and aft and measures the Doppler (red or blue shift)
of the light bouncing back from dust, droplets, and other particles
carried by the wind. Combining two different measurements at
the same point will give the wind speed and direction.
While they have been used extensively in storm
campaigns, they have not been flown together. In addition, the
CAMEX-3 instrument suite comprises radar, visible and infrared
sensors, three laser-based instruments, and dropsondes, which
are instrument packages that are parachuted into the storm. |
"Intensity is the big thing," Hood said. "The
hurricane community has made great strides in making more accurate
forecasts and tracking. But how intense that hurricane's going
to be when it hits the shoreline - or why some storms die out
and others just keep going and going - is the important factor."
It all comes down to thermodynamics, the physics of heat.
Water absorbs energy from the air or sunlight when it goes from
sea surface to vapor, and surrenders energy to the air when it
turns from vapor to rain drops.
Where the energy changes hands is what powers the hurricane,
pumping up the winds which ultimately do most of the damage either
directly or by driving waves ashore to form a storm surge.
To measure that energy exchange in seemingly clear air as
well as in clouds, NASA will take a different look than hurricane
hunters normally take.
"The big thing is that we're flying at higher altitudes
than the other agencies normally fly," Hood said. "Routine
flights at these altitudes haven't been done in the Atlantic
since the 1950s. The DC-8 and the ER-2 each have done it once
out in the Pacific, but no one had focused on Atlantic hurricanes.
"
The
DC-8 (right) is a jetliner modified to carry scientific equipment
instead of passengers. Most of the instruments look through optical
ports designed to give a crystal clear view that passengers never
get through scratched plastic windows.
The ER-2 (below) is the Earth research version of the famous
U-2 spy plane. It carries fewer instruments, but at altitudes
twice as high as the DC-8, 21 km (70,000 ft.) as compared to
10 km (33,000 ft.). In addition, the instruments are different
from the equipment that NOAA carries on its WP-3D Orion aircraft
(modified submarine hunters).
"The big thing is that we're
bringing space flight technology to bear," Hood said. "A
lot of these instruments either have versions flying on satellites
now or are prototypes for new satellites. We're bring NASA technology
to the picture, satellite and remote sensing technology in particular,
and we're trying to give the hurricane research community data
that they don't have, data at high altitude where their aircraft
don't fly."
NASA will even use lasers to gauge wind speeds and directions.
"MACAWS - the Multicenter Airborne Coherent Atmospheric
Wind Sensor - is what I consider to be cutting edge; that's brand-new
technology," Hood said.
"We
want to see how well MACAWS measures the wind structure within
the storm. It has the potential to measure both horizontal and
vertical winds, and that's something that's really important
to understand if you are trying to understand what the hurricane's
going to do. But it has limitations. It doesn't work in dense
clouds."
Right:
A typical flight plan for the vortex experiment is overlaid on
a satellite image of Hurricane Fran from Sept. 4, 1996. The yellow
lines indicate the paths of both the ER-2 and DC-8 starting from
Patrick AFB on the east coast of Florida. The red dots indicate
indicate where dropsondes - instrumented pacakages - will be
parachuted into the storm. A similar pattern will be flown for
the eye dynamics experiment. On one diagonal, the DC-8 will spiral
down into the eye for detailed measurements. The ER-2 will fly
a figure-8 so it can resume a parallel track with the DC-8. At
right, both aircraft fly a set of bent diagonals in order to
measure wind speeds. Credits: NASA. Links to a 1280x1024-pixel,
467K JPG. A smaller 640x512,
124K JPG has major geographic features labeled. Credit: NASA.
MACAWS and other instruments aboard the aircraft will produce
several gigabytes of data that will be the eventual legacy of
CAMEX-3.
"We're going to push real hard to get the data on line
as soon as possible," Hood said. Browse or summary versions
of the data will be available in 3 months, and the first complete
data sets will be available starting in 6 months.
"NASA scientists will be
doing hurricane research, but the bigger goal is to provide the
data to the whole hurricane research community," Hood said.
It's not the biggest weather exercise NASA has ever mounted
to study tropical meteorology - the TOGA-CORE project in 1995
in the Pacific was - but it holds the record for the Atlantic.
Like a hurricane,
CAMEX-3 started small and gathered strength. The CAMEX 1 and
2 experiments were modest activities staged out of NASA's Wallops
Flight Center on Wallops Island, Va., and just using the ER-2.
"CAMEX-3 started off as a really small, quiet experiment,
and got big really fast," Hood explained. "NASA looked
at all these instruments it had doing similar things and said,
'Well, why don't we pull these things together, they're all so
complementary, why don't we pull them all together for one big
experiment?'."
Above :
If the timing and other factors work out right, the Lightning
Imaging Sensor aboard the Tropical Rainfall Measurement Mission
(TRMM) satellite will observe at the same time as the ER-2 and
DC-8. An example of the data that may be returned can be seen
in this picture of lightning flashes in the eyewall and rainbands
of Hurricane Linda as observed by the NASA Optical Transient
Detector (OTD; an LIS forerunner) on Sept. 12, 1997 (2115-2119
UTC). The flashes are superimposed on the OTD near-infrared background
images. Links to 600x114-pixel,
82K GIF. Credit: NASA/Global Hydrology and Climate Center.
A realvideo
movie of Hurricane Linda is also available. (Requires Realvideo player, version 5.
Click to download the RealVideo
Player from RealNetworks, Inc.)
It was merged with the Texas-Florida Underflight (TEFLUN)
experiment in which the DC-8 and ER-2 fly along the same track
as the TRMM satellite to help calibrate the satellite's radar,
microwave, and lightning instruments.
Other federal agencies also recognized this as an opportunity
to broaden their research, and soon CAMEX-3 was growing. It now
involves five aircraft, several satellites, and dozens of ground-based
meteorology stations across the western Atlantic.
"It's a partnership," Hood continued. "We're
trying to teach them more about our remote sensing techniques.
The operational community is going to show us what works and
what doesn't work, so in the long run it's going to help NASA
design better satellites."
But first, they have to take the test models through
the hurricanes. The ER-2 pilot will have the easiest ride since
he will be well above the clouds and turbulence. The DC-8 crew
will be flying near the top of the hurricane where relatively
little work has been done with modern instruments.
Right:
One example of a hurricane's wind energy is this sheet of plywood
driven through the trunk of a palm tree.
"We're going to be really
cautious," Hood said. "The prediction from NOAA is
that it is not going to be much worse than flying through regular
clouds." But the DC-8 crew will pick safe areas and avoid
regions with hail, dense rain, and other indications that the
storm could knock them down. "We're going to try not to
go through severe turbulence."
The teams will also fly well-defined patterns in an effort
to get simultaneous measurements at low, medium, and high altitudes.
One pattern will trace three diagonals across the hurricane.
On one leg, the DC-8 will spiral down into the eye, then climb
back out and resume its track across the hurricane. The ER-2
will fly a figure-8 so it will be in place to resume the same
leg in place with the DC-8. Another pattern will slightly bend
the diagonals to match the circulation patterns within the storm.
Unlike a space mission, this campaign has no preset flight
dates. It has a certain number of flying hours budgeted, so the
team will use them carefully as the storm approaches land. Hood
is especially interested in what happens as the storms makes
landfall and the energetic interplay of air and water is changed.
Web Links |
August
13 Update: Calibration flight planned today - CAMEX first flight to validate Tropical
Rainfall Measuring Mission satellite measurements.
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. |
|
Because this is a research mission that will generate volumes
requiring months of analysis, there will be virtually no benefit
to hurricane forecasters this year. As understanding grows out
of the studies, meteorologists will recognize a few key aspects
of a hurricane's life that, properly diagnosed, will help them
in predicting where the most damage if likely to occur. |
|