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Science Briefing

One of the biggest physical-science meetings ever held in Boulder will sweep into town over the Fourth of July weekend. The International Union of Geodesy and Geophysics (IUGG) is holding its XXI General Assembly on the University of Colorado campus from 2 to 14 July. Up to 5,000 attendees from as many as 78 nations are expected. The hosts are CU and the IUGG committee of the U.S. National Academy of Sciences.

Founded in 1919, the IUGG is dedicated to scientific study of the earth and application of the ensuing knowledge to society. Its realm includes hydrology, oceanography, solar-terrestrial relations, and atmospheric sciences as well as geology. The meeting at CU will include eight parallel tracks corresponding to the eight autonomous associations that make up the IUGG. One of those is the International Association for Meteorology and Atmospheric Sciences, which will hold symposia on atmospheric electricity, climatic variability over the past millenium, aspects of the Mt. Pinatubo eruption, and two dozen other topics.

Among the many NCAR scientists involved in the meeting:
* Paul Song (HAO) is lead convenor of a symposium on connections among the earth's magnetosheath, magnetopause, boundary layers, and cusp.

* Art Richmond (HAO) is coconvenor of a symposium on the equatorial atmosphere and ionosphere interactions.

* Rolando Garcia (ACD) is lead convenor of a set of four symposia on the middle atmosphere. Byron Boville (also of ACD) is coconvenor for the session dealing with dynamics.

Advance registration for the meeting has already closed. On-site registration will take place at Balch Fieldhouse on 1 July (1:00-5:00 p.m.); 2 July (1:00-6:30 p.m.); and 3 July onward (7:45 a.m.-2:30 p.m.). Standard fees are $410 for the full two weeks or $215 for a single week.



Could a series of colossal hurricanes have caused one or more massive extinctions of dinosaurs and other species? A numerical hurricane model cocreated by Rich Rotunno (MMM) is illuminating that question. In a paper forthcoming in the Journal of Geophysical Research, Rich joins lead author Kerry Emanuel (Massachusetts Institute of Technology) and three others to 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.

Photo of Rich Rotunno

Rich Rotunno. (Photo by Curt Zukosky.)

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 50deg.C.

Rich took a hurricane model he created with Emanuel in the 1980s and tested it under these conditions. The 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 m/s. The paper notes that such storms might globally saturate the 100-200 millibar layer in about 20 days, producing vast sheets of stratospheric clouds that would alter radiation patterns and perhaps trigger ozone depletion.

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



As of 1 June, the UCAR Office of Programs has a new director: Bill Pennell, who comes to us from the Department of Energy's Pacific Northwest Laboratory (PNL) in Richland, Washington. He replaces Bill Bonner, who headed UOP since its formation in 1992. UCAR president Rick Anthes, in announcing the appointment, said, "Bill brings to the position of director of UOP a strong scientific research background, excellent experience in project management, interactions with the university and NCAR scientific community, and strong interactions with federal agencies."

Photo of Bill Pennell

Bill Pennell. (Photo by Bob Bumpas.)

At PNL, Bill was program manager of the Global Studies Program, which works toward an integrated understanding of the interactions between human activities and the environment. He also served as special assistant to Martha Krebs, director of DOE's Office of Energy Research, in her role as chairwoman of the Air Quality Subcommittee of the Committee on Environment and Natural Resources.

Bill's areas of expertise include boundary layer meteorology, atmospheric turbulence, atmospheric flow and dispersion over complex terrain, meteorological and air quality field experiments, design of aircraft instrumentation for meteorological measurements, and renewable energy resource assessment. His experience includes a six-year stint at NCAR, first as a postdoctoral fellow in the Advanced Studies Program, then as a researcher in the Atmospheric Analysis and Prediction Department (now the Climate and Global Dynamics Division). As part of the Global Atmospheric Research Program, he studied the atmospheric boundary layer's turbulence structure and interaction with cumulus clouds and the transfer of heat and mass across the air-sea interface. He was also involved in planning and implementation of two of GARP's major international field programs. Bill has degrees in mechanical engineering from the University of Florida (bachelor's) and University of Minnesota (master's and doctoral).

Bill Bonner, who retired from the UOP post 5 May, is not retiring from research; he plans collaborative work with colleagues in MMM, as well as some writing and lecturing. Bill plans to continue to serve as chair of Clark Atlanta University's External Advisory Panel.


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Edited by Bob Henson, bhenson@ucar.edu
Last revised: Wed Mar 29 16:34:08 MST 2000