UCAR > Communications > UCAR Quarterly > Spring 2001 Search

Spring 2001

Science Bits

NSF grant extends support for interconnecting national research networks

NSF has awarded $2.5 million to the National Laboratory for Applied Network Research (NLANR) to continue technical, engineering, and traffic analysis support to the high-performance networking and applications communities. The grant extends by one year NLANR's original three-year cooperative agreement to support universities and institutions in connecting to the nation's research networks.

NLANR is a collaboration of NCAR, the National Center for Supercomputing Applications (NCSA) at the University of Illinois at Urbana-Champaign, the Pittsburgh Supercomputing Center (PSC), and the San Diego Supercomputer Center (SDSC). The partnership helps more than 170 NSF- funded High-Performance Connections sites connect to and use high- performance research network backbones like NSF's vBNS (very high performance Broadband Network Services).

NLANR develops software to help scientific users and network administrators, while designing analytical tools to help networks run smoothly. The NLANR staff works with researchers and staff at small- to mid-sized campuses and with commercial service providers, resulting in a broad impact on the networking and application communities. The award will be divided among three NLANR program teams:

  • The Distributed Applications Support Team at the NCSA. This team helps researchers maximize performance of their distributed applications. The staff delivers training sessions around the country and demonstrates NLANR-developed tools.

  • The Engineering Services Team, a collaboration between the PSC and NCAR. This team provides engineering support for the integration and use of advanced network services between commercial providers and campus infrastructures. The team offers the NLANR on-site program that provides courseware and hands-on training tailored for network engineers and scientists in various disciplines.

  • The Measurement and Network Analysis Team, based at SDSC. This team has created a network-analysis infrastructure by deploying devices to measure performance and flow at more than 100 locations across the networks. Products include statistical tools for analyzing and visualizing traffic patterns.

    National Center for Supercomputing Applications, Pittsburgh Supercomputing Center, San Diego Supercomputer Center, NCAR, University of Illinois

    Planetary waves have a role in plankton production

    Three University of Rhode Island scientists have discovered that planetary waves traveling thousands of miles have a significant impact on the abundance of phytoplankton in the upper ocean, and may play a role in predicting global warming.

    In a paper published in Nature, Mete Uz, James Yoder, and Vladimir Osychny reported on their two-year analysis of satellite- derived data on chlorophyll and sea-surface height. The data show that oceanic planetary waves—which travel in a westward direction—are associated with 5–20% of the variability in chlorophyll concentration. The scientists theorize that disturbances in the ocean caused by these waves are bringing nutrients to surface waters on a global scale and affecting the production of phytoplankton.

    Uz and his collaborators used ocean color data from NASA's SeaWiFS (Sea- viewing Wide Field-of-View Sensor) program and concentrated on the role of large planetary, or Rossby, waves in enhanced biological productivity. These waves can be hundreds of miles wide, but they are only a few centimeters in height, making them observable only through satellite imagery. A Rossby wave moves so slowly that it could take months or years to cross the ocean. As the wave passes, it causes water motion that pumps more nutrients from the depths to the surface waters of the ocean.

    "For physical oceanography, this study presents one more tool with which to observe Rossby waves, especially their vertical dynamics," said Uz. "For biology, it illustrates for the first time a wave propagating through an ecosystem. This means that at the large spatial and temporal scales at which these waves operate, one cannot think of biology as a functional block separate from physics. If you want to guess what the productivity will be at a given location and time in the future, you cannot use a purely biological model. The coupling between physics and biology is important."

    The study also adds indirectly to the scientific knowledge about the oceanic carbon cycle. Uz noted that variability in the oceans' biological productivity has a significant impact on projections of global climate change. Because we do not know enough about what controls productivity in the oceans, he said, "we are not in a position to make a reasonable guess about how the ocean will respond under different scenarios of global change. However, our research puts in place one more piece of the jigsaw puzzle of [the] oceanic carbon cycle."

    University of Rhode Island

    Scientists watch dark side of the Moon to monitor Earth's climate

    Scientists have revived and modernized a nearly forgotten technique for monitoring Earth's climate by carefully observing "earthshine," the ghostly glow of the dark side of the Moon. Earthshine measurements are a useful complement to satellite observations for determining Earth's reflectance of sunlight, an important climate parameter. Long-term observations of earthshine thus monitor variations in cloud cover and atmospheric particles known as aerosols that play a role in climate change.

    Earthshine is readily visible to the naked eye, most easily during a crescent moon. Leonardo da Vinci first explained the phenomenon, in which the Moon acts as a giant mirror, showing the sunlight reflected from Earth. The brightness of the earthshine thus measures the reflectance of Earth.

    In the 1 May issue of Geophysical Research Letters, a team of scientists from the New Jersey Institute of Technology (NJIT) and the California Institute of Technology report that Earth's albedo is currently 0.297, with a margin of error of 0.005.

    "Earth's climate is driven by the net sunlight that it absorbs," says Philip Goode, leader of the NJIT team and director of the Big Bear Solar Observatory. "We have found surprisingly large—up to 20%—seasonal variations in Earth's reflectance. Further, we have found a hint of a 2.5% decrease in Earth's albedo over the past five years." If Earth reflected even 1% less light, the effect would be significant enough to be a concern with regard to global warming.

    In the early 20th century, the French astronomer Andre-Louis Danjon undertook the first quantitative observations of earthshine. But the method lay dormant until Caltech professor Steven Koonin described its modern potential in a 1991 paper. The newly published data are the first that are precise and systematic enough to infer the relative health of Earth's climate.

    The new albedo measurements are based on about 200 nights of observations of the dark side of the Moon at regular intervals over a recent two-year period, and another 70 nights during 1994–95. Using a six-inch refractor telescope and precise charge-coupled devices at Big Bear, the researchers measure the intensity of the earthshine. By simultaneously observing the bright "moonshine" from the crescent, they compensate for the effects of atmospheric scattering.

    The study relies on averages over long periods, because the albedo changes substantially from night to night with changing weather, and even more dramatically from season to season with changing snow and ice cover. The locations of land masses also affect the albedo as Earth rotates on its axis.

    It is significant that earthshine data suggest that the albedo has decreased slightly during the past five years, as the Sun's magnetic activity has climbed from solar minimum to maximum during that time. This supports the hypothesis that the Sun's magnetic field plays an indirect role in Earth's climate.

    The study was funded by both NASA, beginning in 1998, and the Western Center for Global Environmental Change during 1994–95.

    California Institute of Technology, New Jersey Institute of Technology

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