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October 9, 1998
For more information on these science news and feature story tips, please
contact the public information officer at the end of each item at (703)
292-8070. Editor: Cheryl Dybas
Contents of this News Tip:
A volunteer team of scientists from the National Center for Atmospheric
Research (NCAR), in Boulder, Colorado, and glider pilots from the Soaring
Society of Boulder, spent this past spring exploring an elusive atmospheric
phenomenon from a high-performance, hybrid aircraft called a motorglider.
Supported by the National Science Foundation (NSF) and the University
Corporation for Atmospheric Research (UCAR), the scientists are now analyzing
what was learned about thermal waves -- the gravity waves that sometimes
form above rising columns of warm air called thermals. Thermals are perhaps
best known to hawk-watchers, as these air currents are used by hawks,
eagles, and other birds of prey, as well as by man-made gliders or sailplanes,
to gain altitude in motorless flight.
Thermal waves, which have eluded thorough scientific measurement until
now, may hold one key to better weather forecasts. For glider pilots,
the ability to extend flights over greater distances is an extra benefit
of the research.
Like something out of a James Bond movie, the motorglider takes off
and climbs using its turbocharged engine, draws in its propeller, and
becomes a high-performance glider. While gliding, the pilot can restart
the engine, pop the propeller out, and resume powered flight. These features
allow researchers to gather data from individual thermals and to travel
between and above promising cloud structures in search of the waves. With
the craft's 77-foot-wide wingspan and 1,000-mile range, the team was able
to explore thermal waves far from the glider's home base in Colorado.
Researchers ventured to South Dakota and Nebraska, where they tracked
thermals without interference from the mountain waves that form above
the Rocky Mountains. [Cheryl Dybas]
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Scientists working under the aegis of the international Ocean Drilling
Program and funded in large part by the NSF will investigate whether a
large area of reef growth, similar to the modern Great Barrier Reef, could
have developed off southern Australia 15 million years ago. The researchers
will be aboard the world's largest scientific drillship, the JOIDES Resolution.
They depart Wellington, New Zealand, on October 13th for the Great Australian
Bight.
Reef-building corals are sensitive to temperature variations, typically
growing only in warm waters. The appearance and subsequent demise of an
extensive coral reef system in an area bathed by cool waters today may
be the result of global climate fluctuations during times past.
The expedition will drill in water depths between 200 meters (some 650 feet) and 4.5
kilometers (nearly three miles) and will recover cores from up to 1.2
kilometers (three-quarters of a mile) beneath the seafloor. Scientists
from 11 countries will work together to determine whether a "Little Barrier
Reef" did in fact exist, and to understand how the Southern Ocean evolved
in response to changes in climate, ocean circulation, and sea-level. Clues
found in deep-sea sediment cores will shed light on how past sea-water
temperature variations influenced the type of reef-building organisms
growing off South Australia. Oceanographers may soon know what happens
on the seafloor when it's too cold for such reef-building corals to grow.
[Cheryl Dybas]
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It is an obvious enough statement: An acre of grass is packed more densely
with individual plants than an acre of forest. But the question remains,
why? Traditionally, plant ecologists thought that the size of a given
plant determined the relationship between how big it gets and how many
plants can live together in the same area. This measure of how close plants
can grow together is known as the "thinning law." NSF-funded researchers
Brian Enquist and James Brown of the University of New Mexico have found
that the thinning law can be better understood by studying the size of
individual plants and the amount of energy they use. If available energy
levels are the same, it turns out that the law works for all species,
whether plant or animal. The mathematical description of this plant thinning
law is identical, whether the species is an animal or a plant, says Brown.
"Common theories can explain many unifying aspects of biology. This
points to an interesting regularity in nature -- that the total amount
of energy used on a given space on earth does not vary with body size," explains
Enquist. Put more simply, there's only so much to go around, whether you're
an animal or a plant. [Greg Lester]
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