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Knowledge for All
  • Knowledge for All: timeline
  • In their own words: John Zillman
  • UCAR at 40
    Who We Are
    Introduction
    One Planet, One Atmosphere
    Between Sun and Earth
    Measuring and Modeling
    When Weather Matters Most
    Spreading the Word
    •Knowledge for All
    Looking toward the Future
    UCAR at a Glance
    List of acronyms


    Fiber-optic cable is one of the tools that revolutionized communication for NCAR's research community in the 1990s.

    Sometimes a single observation can change the course of weather research. Theodore Fujita saw a starburst-like pattern in a set of downed trees while flying above the twister-ravaged Midwest in 1974, soon after the nation's worst tornado outbreak. The University of Chicago professor was the world's leader in analyzing tornado damage patterns. He had unraveled the paths of twisters by analyzing the swirling patterns of debris left by buildings and vegetation. This starburst puzzled Fujita, though. It looked as if a bundle of air had crashed to the ground and flowed in all directions, rather than converging and rising inside a tornado.

    Before long, Fujita had coined a new term—microburst—to describe the phenomenon he'd discovered. A 1975 airline crash in New York City also appeared to Fujita to be microburst-related. Many colleagues were skeptical, but he found a receptive ear at NCAR. After extensive teamwork and planning led by John McCarthy, NCAR hosted two field programs in the early 1980s to analyze storms passing near Denver's airport. Using Doppler radar and other instruments, the research team proved that Fujita's hunch was correct: microbursts were frequent, and they posed a serious threat to aviation.

    Rita Roberts analyzes radar data in a 1992 experiment on thunderstorm prediction.

    That threat has since been countered by years of painstaking work at NCAR and collaborating institutions. A nationwide microburst-detection network has been installed at dozens of major airports. It combines data from ground-based instruments and radar using software that mimics a human's decision-making process. Microburst-related crashes and injuries have dropped dramatically since the warning system was put in place; no airports with the improved system have recorded a fatal accident related to wind shear. Similar systems are in place or are being developed for airports in Australia, Hong Kong, Korea, and Singapore.

    The research program that helped tame microbursts evolved into one of NCAR's largest activities. Now addressing a wide range of other weather hazards to aviation, the Research Applications Program is a prime example of what UCAR and NCAR make possible. A disparate group of parties—scientists from several universities, the Federal Aviation Administration (FAA), major airlines—joined forces to stimulate research that otherwise might not have occurred.

    This sort of teamwork happens in many other ways facilitated by UCAR. Far-sighted ideas have a chance to take root. National borders are transcended through collaboration. Technology is designed to fit real- world needs while advancing research goals. The fruits of this labor are helping lead to a better, and better-understood, world for everyone.

    Safer skies

    Air travel is exquisitely weather-sensitive. According to the FAA, some three-quarters of all flight delays are weather-related, costing the nation billions of dollars. Thanks to over a decade of support from the FAA, NCAR has made a dent in that total by helping airlines to route their flights around bad weather more efficiently. Much of this work has been accomplished by blending the latest sensing technology with specialized computer algorithms. This software reads between the lines of the data and finds the weather hazards that lurk within.

    Many thunderstorm-related threats to aviation have been tamed by warning systems developed through NCAR-based research.

    For example, the Auto-nowcaster, pioneered by James Wilson, Cynthia Mueller, and colleagues in the mid-1990s, uses radars, satellites, ground stations, and weather balloons to pinpoint where thunderstorms—the leading cause of flight delays—are occurring. It then "nowcasts" their growth and motion up to an hour ahead. The system helps air traffic controllers anticipate when storminess might impede takeoffs and landings. In a similar vein, NCAR has created snow-prediction schemes that project accumulation rates over a half hour. Such knowledge can save thousands of dollars on a single day by postponing runway closures or flight delays until they are actually needed.

    A new NCAR project aims to improve forecasts of cloud ceiling and visibility by combining observations with very short range computer models. This technique has already led to better forecasts of in-flight icing. Meanwhile, a team led by Roy Rasmussen found that visibility alone was a poor indicator of the need to deice planes. Small, dense snowflakes can pile ice onto wings more quickly than larger snowflakes, even if the latter have a greater effect on visibility. New deicing guidelines focus on the mass of the snow rather than visibility.

    Research by NCAR and collaborators in the 1980s uncovered the deadly one-two punch of microbursts: aircraft level off when they encounter headwinds, then find themselves pushed to the ground by intense downdrafts and tailwinds.

    Only recently has turbulence shown its invisible hand to the NCAR aviation group. In 1998 NCAR teamed with United Airlines to test a new approach that uses the impact of turbulence itself as a measurement tool. The aircraft's response is sensed and the turbulence inferred, once per minute, through a technique that accounts for the plane's vertical acceleration, weight, air speed, and other variables. In another promising approach, Larry Cornman has been collaborating with NASA and industry to develop a way to extract turbulence information from the data on wind and precipitation acquired from a plane's standard Doppler weather radar.

    NCAR's strong relationships with the aviation community have made these and other advances possible. To help fulfill long-term goals supported by the FAA and other national and international sponsors, NCAR scientists interact with engineers and developers from major airlines to determine how planes and pilots handle weather and what the industry needs. In turn, the airlines sometimes make their aircraft available for gathering data and testing new software, as in the turbulence detection program. NCAR developers also work with others across the aviation spectrum, including commuter airlines, business users, and private pilots.

    In the mid-1990s, NCAR's aviation expertise went abroad. The center forged partnerships with the Hong Kong Royal Observatory and the Hong Kong University of Science and Technology, and NCAR became the main subcontractor for weather safety at one of the decade's most ambitious public works projects, the Chek Lap Kok airport. NCAR helped to adapt software and sensing tools to detect and warn for turbulence in the unique setting of the new airport, where a kilometer-high mountain sits only a few kilometers from the runways.

    The main contractor for the Chek Lap Kok weather safety installation was Weather Information Technologies, Inc. (WITI), a for-profit subsidiary of the UCAR Foundation. The foundation was created in 1986 as UCAR's agent for bringing NCAR technology into the commercial realm. Profits from activities led by the foundation help support new NCAR research. Early in 2000, Lifeminders bought WITI's services that send personalized e-mails, including weather information, to more than 10 million subscribers.

    Crossing borders

    Even before NCAR was established, its founder-to-be, Walter Orr Roberts, recognized the need to place scientific cooperation above politics. As the director of the High Altitude Observatory, Roberts reached out to solar physicists behind the Iron Curtain. A decade after his death, Roberts's global perspective continues. UCAR's International Affiliates Program includes nearly 40 institutions on six continents. Through the program, these universities and laboratories connect with each other, help plan international research campaigns, and often send affiliate scientists to Boulder for on-site work.

    Geologic hot spots around the globe are monitored by a UCAR-based network of Global Positioning System receivers. The technology was adapted in the 1990s for weather observing. (Photo by Charles Meertens, UCAR)

    One UCAR technology that has truly spanned the globe is its GPS-based Earth sensing tools. A consortium of over 100 universities joined the UCAR family in 1991 after pioneering the use of compact sensors that interpret signals from Global Positioning System satellites to trace the motion of Earth's crust. Sensitive to within millimeters, these instruments have been placed atop Mount Everest and on some 4,000 other points in over 40 countries.

    Better earthquake monitoring and detection were the main benefits of the GPS program at first, but once under UCAR's umbrella, it set its sights on the sky. By measuring a slight bend in the GPS signal caused by the atmosphere—at first considered mere noise—it seemed possible to extract useful information and, with other data, measure temperature, water vapor, and pressure in the stratosphere and troposphere and electron density profiles in the ionosphere. In the 1995 GPS/Meteorology experiment (GPS/MET), a prototype receiver showed that a space-based instrument could successfully intercept GPS signals that pass into and out of the atmosphere at a tangent to Earth's surface. Someday, a constellation of such receivers might help provide global profiles of the atmosphere at a far greater density and frequency than now available, especially over the oceans.

    An equally ambitious plan is already taking shape across the United States. Launched in 1999, SuomiNet (named after Verner Suomi, the University of Wisconsin–Madison pioneer in satellite meteorology) is a collection of ground-based GPS receivers that operate in much the same way as the space-based prototype. With over 180 participating institutions on board, and many more expected, SuomiNet promises to provide thousands of new observations each day. Its founders, including UCAR's Randolph Ware and David Fulker, hope the network will also stimulate the interest of students at participating universities, who will work closely with the hardware and the real-time data.

    A network of possibilities

    A UCAR-based network of GPS receivers tracks the Earth's crustal plates in motion. Shown here (in exaggerated scale) are the relative motions of receiver sites around the world. GPS signals are now being used to infer atmospheric moisture and electron density.

    The ultimate collaborative tools at the start of the new century—the Internet and the World Wide Web—have allowed UCAR and NCAR to fulfill their primary missions in fresh ways. NCAR was one of the original nodes on NSFnet, the embryonic, NSF-funded academic research network of the 1980s and 1990s. Scientists who formerly had to travel to Boulder to use NCAR's computers could now log on remotely, speeding their work immensely.

    NCAR's networking capacity developed hand in hand with its computing resources and the needs of the research community. When the Internet moved from the public to the commercial realm in 1995, NCAR made the switch to the NSF-funded very high speed Backbone Network Service (vBNS) to ensure that university scientists had the access they needed. In 1999 NCAR joined the University Corporation for Advanced Internet Development, a group of over 170 universities sharing a corporate-loaned fiber-optic network and building the nation's next-generation research network, Abilene.

    The need for ultra-fast, high-volume connections between NCAR's two main laboratories in Boulder led UCAR to join a unique, home-grown consortium. A set of dedicated fiber-optic lines now links the two NCAR labs with the Boulder labs of the National Oceanic and Atmospheric Administration, the University of Colorado, and the city of Boulder. Funded by its participants, the Boulder Research and Administrative Network takes advantage of Boulder's dense concentration of research- oriented organizations to create links that should fulfill networking needs for years to come.


    UCAR at 40
    Who We Are
    Introduction
    One Planet, One Atmosphere
    Between Sun and Earth
    Measuring and Modeling
    When Weather Matters Most
    Spreading the Word
    •Knowledge for All
    Looking toward the Future
    UCAR at a Glance
    List of acronyms


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    Executive editor Lucy Warner, lwarner@ucar.edu
    Prepared for the Web by Jacque Marshall
    Last revised: Fri Jan 26 17:18:32 MST 2001