Camera of many colors
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Camera of many colors
NASA looks Bonnie in the eye again
this morning with a space-age camera
Aug.
26, 1998: (this is the tenth 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.)
As Bonnie wades ashore, its days become numbered. It is now disconnected from its major power source - the warm, moist air over the ocean - and will weaken over the next few days as it becomes part of the continental weather pattern.
Right: The NASA ER-2 is looking Bonnie in the eye again this morning. At right is a composite of the ER-2's ground track, and a GOES-8 satellite image. (links to 519x513-pixel, 174KB JPG).
Measuring how much energy it can tap from the atmosphere, and where it distributes the energy, is a primary task for the Multispectral Atmospheric Mapping Sensor (MAMS), one of several instruments that look out from the belly of the NASA ER-2 aircraft as it sails 20 km (65,000 ft) above Bonnie.
 | It's a camera of many colors, providing scientists with images in the colors that our eyes know, and in the near- and thermal-infrared that only technology can let us see. "What we're going to get are some very good images, high-resolution data, which will depict cloud features and tops," said Dr. Anthony Guillory, a scientist with NASA's Marshall Space Flight Center working at the Global Hydrology and Climate Center in Huntsville, Ala. Guillory is the MAMS principal investigator for CAMEX-3. |
"Live, via satellite"While that expression lost its novelty for most home TV viewers some years ago, it's turning the CAMEX-3 science team into virtual hitchhikers. While NASA's ER-2 (below; links to 777x216-pixel JPG) prowls above Hurricane Bonnie, the science teams have a ringside seat instead of having to wait several hours for data tapes to come back with the plane. They are watching by way of the same Tracking and Data Relay Satellite System used by the Space Shuttle, Hubble Space Telescope, and other genuine "high fliers."
Starlink delivers images in "real time" - the pictures below were pulled off the Starlink web server a few seconds after they were recorded this morning. The system also uses the Global Positioning System to track the ER-2's position to generate maps like the one above (combined with a GOES-8 satellite image). Starlink also lets the scientist fine-tune his instruments even though they are hundreds or thousands of kilometers away. |
"We'll be able to look at the water vapor in the lowest levels of the atmosphere and at high altitudes."
Ironically, while a hurricane is powered by warm moisture, it's cold moisture - ice, or even snow, as spotted on Sunday - that betray the energy of the storm.
"High, cold clouds mean more convection
and more intensity," Guillory explained. Moisture does not
naturally percolate to the upper levels of the troposphere, the
thick lower atmosphere where we live. It is pushed there by strong
vertical winds. As the air rises, pressures drop and moisture
becomes droplets and then ice crystals.
"We will be looking at the water vapor
in the lowest levels of the atmosphere and at high altitudes,"
Guillory said.
Right: Courtesy of Starlink are four frames of MAMS data taken before 8 a.m. EDT today. Individual images tell almost none of the story. Scientists will learn more about hurricanes by compiling image strips (like the one at left from an earlier campaign; links to 89x882-pixel JPG) from the ER-2 flight, and combining data from other instruments aboard aircraft and satellites. (links to 736x736-pixel, 206KB JPG.)
As it looks through the belly of the ER-2, MAMS scans from side-to-side, viewing a 37 km (23-mi) wide swath below it. Every hour the instrument cranks out another strip of data 748 km long with a resolution of 100 meters (328 ft) at the center (it's slightly coarser towards the edges of the view).
Image strips are produced in eight visible/near infrared channels and in four thermal infrared bands. They show surface features, clouds, and atmospheric constituents (primarily water vapor), plus precipitable water and skin temperature (land or sea surface). Features that MAMS measures include: total precipitable water, land and sea surface temperature, upper-level humidity, cloud detection, cloud mean top temperature, cloud mean height (pressure).
"These will go a great distance in determining the intensity and evolution of a storm," Guillory said.
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Weather forecast
Bonnie is about to become history, but Danielle is powering up and probably will become the next target for the CAMEX-3 team.
Bonnie
has finally started moving, and is expected to hit land Wilmington,
N.C. early this afternoon, although it is erratic enough to change
its mind. According to CAMEX meteorologists Tuesday afternoon,
central pressure in the storm has remained fairly constant over
the last 24 hours, but this could change in short order as Bonnie
starts sucking up moist Gulf stream water.
Left: This animated GIF combines several GOES-8 infrared images of Bonnie to depict its movement over the last few hours. (links to larger, 616KB animated GIF)
The apparent weakening for the last couple days may be due to the surface upwelling in the storm center vicinity; this is borne out by sonde termination temperatures in the 27-28 deg. C (81-82 deg F) region seen last night, the extinction of the eye wall in the west-south region, and the widening of the maximum wind bands.
Danielle, meanwhile is expected to intensify with a track following that of Bonnie for the next couple of days. She is well formed and symmetric with winds about 74 km/h (46 mph; 40 knots).
Over the next day to two days, Bonnie's days are numbered. By tomorrow this time she will be into North Carolina and recurving back out to sea, possibly right over DC. Danielle, meanwhile is expected to intensify with a track following that of Bonnie for the next couple of days.
Over the next two to three days, Danielle should be in the vicinity of Puerto Rico, and might be flyable at the end of the period. Showers here increasing for the next few days. And for 3 to 5 days, watch Danielle; she could be another CAMEX storm.
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. 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)
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