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Open House

On 22 April, UCAR and NCAR jointly celebrated their 35th anniversary with an open house at all three Colroado locations: the Mesa Laboratory and Foothills Laboratory in Boulder, and the Research Aviation Facility at Jefferson County Airport near Broomfield. The date was chosen to coincide with the 25th anniversary of Earth Day and the beginning of National Science and Technology Week. Over 2,500 visitors toured facilities or viewed exhibits and demonstrations.

Sara Klingenstein gets a charge out of a Van de Graaf generator that was part of a hands-on demonstration for youngsters.


Steven Palmer (right) explains how the computer-controlled equipment in the machine shop works.


Young visitors watch the simulated tornado that is one of the permanent exhibits designed at the Exploratorium science museum in San Francisco.


NCAR scientist Lee Klinger (far right) explains the work being conducted in the Frost Phytotron, a computerized greenhouse.


(Photos by Carlye Calvin and Curt Zukosky.)


Science Bits

Massachusetts Institute of Technology, NCAR

Hypercanes and mass extinctions

Could a series of colossal hurricanes have caused one or more of the massive extinctions of species evident in the geologic record? A numerical hurricane model created by MIT's Kerry Emanuel and NCAR's Richard Rotunno is illuminating that question. In a paper forthcoming in the Journal of Geophysical Research, Rotunno, Emanuel, and three others make the case that hypercanes-- theoretical hurricanes that develop over super-warm waters and grow far beyond their usually observed strengths--may have been a crucial agent in these extinctions.

During the Late Permian period, about 245 million years ago, some 96% of all species disappeared. A later event extinguished 75% of all species. Giant meteors or volcanic eruptions have been cited as possible causes. The authors contend that neither type of event could inject enough long-lasting material into the stratosphere to affect global climate on the scale needed for mass extinction. However, meteors or undersea eruptions might have been able to heat swaths of ocean a few tens of kilometers wide to temperatures as high as 50 degrees C.

Rotunno took a hurricane model he created with Emanuel in the 1980s and tested it under these conditions. The simulated superheated patches of ocean quickly generated tropical cyclones with pressures as low as 200 millibars and wind speeds as high as 300 meters per second (approaching the speed of sound). After about two days, the storms settled into a steady state with winds still around 150 meters per second. The paper adds that such storms might globally saturate the 100-200 millibar level in about 20 days, producing vast sheets of stratospheric clouds that would alter radiation patterns and perhaps trigger ozone depletion.

Although Rotunno notes that the model was not designed to run with such extreme conditions, "we believe the results are physically reasonable, and in the paper we suggest avenues for future improvements."

El Niño, 1990-95: R.I.P. (for now)

The Methuselah of this century's El Niño events was laid to rest this spring, albeit with some signs that it may be dormant rather than dead. The El Niño began late in 1990 as warm temperatures in the western Pacific Ocean began spreading eastward. The onset was well- advertised by several computer models, bringing hope that prediction of the El Niño-Southern Oscillation (ENSO) was finally within reach.

It turns out that current models are much better at pegging the arrival of El Niño than its departure. Several forecasts that El Niño would end between 1992 and 1994 were for naught. The warm waters continued a pattern of advancing into the eastern Pacific and partially retreating into the central and western Pacific. (One of these cycles came during the Central Equatorial Pacific Experiment in early 1993, giving researchers a closer look at the ENSO process.)

The Southern Oscillation Index, which is the difference in sea-level pressures between Tahiti and Darwin, Australia, is normally negative during El Niño. It rose to zero for only a single four-month period between early 1991 and early 1995 and never ascended into positive numbers.

By April of this year, following a moderately strong resurgence, El Niño quickly weakened, with a small zone of eastern equatorial Pacific waters actually becoming cooler than normal. NOAA's Climate Analysis Center issued its last monthly advisory on this El Niño in April, noting the pattern change, but Darwin pressures remain high. Some scientists at NCAR and elsewhere think the nature of ENSO itself may be changing due to long-term rises in sea-surface temperatures (SST) over the entire equatorial Pacific.

"There is the possibility that the mean SST regime in the Pacific has warmed up due to some kind of longer-term fluctuation," says NCAR climatologist Gerald Meehl. "In that case, you could have oscillations occurring that are superimposed on that warmer mean. If you compare these recent oscillations to the older mean, it's all going to look relatively warm, like a perpetual El Niño." Current practices compare temperatures to the 1951-80 average, which precedes the oceanic warming of the 1980s and 1990s. "If the average state of the climate system is undergoing longer-term fluctuations, then what you define as an El Niño or La Niña depends on what you take as the mean itself." Stay tuned for the progress of this existential enigma.


James Baker visits UCAR

D. James Baker (foreground center), under secretary for oceans and atmosphere for the U.S. Department of Commerce and administrator of NOAA, visited UCAR in late March. Here, he gets a briefing on NCAR's Aviation Weather Development Laboratory by Sandra Henry and James Wilson. NCAR director Robert Serafin is at far left. (Photo by Curt Zukosky.)


New directions for the Roberts Institute

The Walter Orr Roberts Institute, formed in July 1993 to honor and carry on the ideals of UCAR's founder, is undergoing a transformation aimed at better serving the UCAR community and constituents. The formal infrastructure of the institute is ending, but the activities it encompassed and the vision it embodied--science in the service of society--will be pursued in other ways and other forms. The programs and activities under way in the institute are being shifted to other parts of UCAR (NCAR, UCAR Office of Programs, or the UCAR Corporate Office). The private funds donated to the institute will be preserved in a special fund named the Walt Roberts Trust. This fund will be used to help initiate or support projects that meet the spirit of the institute and will continue to honor the memory of Roberts. An early emphasis will be on outreach and education activities. The fund will be administered by the UCAR president's office under the advice of a small selection committee of internal and external people interested in the work and mission of the Trust.

Robert White returns to UCAR

Robert White. (Photo courtesy National Academy of Engineering.)

Former UCAR president Robert White has been named a senior UCAR fellow, current president Richard Anthes has announced. White, retiring president of the National Academy of Engineering (a position he has held since 1983), assumed his new post 1 July. This pro bono position will enable White to continue his lifelong history of contribution to U.S. science. He has served as chief of the U.S. Weather Bureau (now the National Weather Service), first administrator of the National Oceanic and Atmospheric Administration, president of the Joint Oceanographic Institutions, administrator of the National Research Council, executive officer of the National Academy of Sciences (NAS), and U.S. representative to the World Meteorological Organization and the International Whaling Commission. He has chaired the NAS Climate Research Board and served on an extensive list of advisory committees and councils.

In his new post, White will assist UCAR in program formulation and act as a senior adviser to the UCAR president. Working out of the American Meteorological Society-UCAR office in Washington, D.C., he will help with sustainable development initiatives and international activities and offer senior-level advice on policy, legislative, and other related issues.


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Edited by Carol Rasmussen, carolr@ucar.edu
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Last revised: Tue Apr 4 09:27:57 MDT 2000