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| 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. Contents of this Tipsheet:
FINE LINE BETWEEN STORMS AND SUNSHINETiny temperature differences can spell the difference between potentially severe storms and no rain at all. Similarly small discrepancies in moisture can have the same effect. These and other aspects of storm development have been analyzed by NSF funded scientist Andrew Crook of the National Center for Atmospheric Research in Boulder, Colorado. Using computer models of the atmosphere, Crook conducted "forward-sensitivity" experiments. These experiments bring a set of slightly varying scenarios forward in time to see how a given weather situation might evolve. Wind, temperature and moisture values are derived from surface, radar and radiosonde (weather balloon) observations. Crook found that a tiny temperature decrease was enough to shut off storm development entirely, while a minute increase led to a four-fold increase in rainfall. Crook's findings reinforce the difficulty in forecasting where and when thunderstorms might develop on days when conditions are borderline. However, this information should help forecasters better quantify the uncertainty in a forecast. [Cheryl Dybas]
ANTARCTIC ICE DRILLERS REACH RECORD DEPTH AT VOSTOKScientists drilling through the ice cap of East Antarctica at Vostok Station, in work supported by the NSF and others, reached a record depth of 3350 meters during this past Antarctic field season and extracted an ice core stretching over the past 400,000 years of climate history. Russian, U.S. and French glaciologists at the Russian base are drilling the core to preserve samples of the Earth's atmosphere. The core will present an archive of past climate reaching much farther back in time than any other ice core. Antarctica's ice cap is the deepest and oldest in the world. Some 30 researchers from the three nations will study Vostok's icy record, which stretches over four entire cycles of glacial advance and retreat. Drilling of this core began in 1990; the researchers hope to extend the current record back to one million years or so. Studies of Vostok's ice have already shown a close link between climate over the past 200,000 years and changing concentrations of greenhouse gasses in the atmosphere. Ultimately, the research will help uncover how the earth's "climate machine" operated in the past, and improve predictions of future climate. A subglacial lake called "Lake Vostok" lies under the station, possibly sealed off from the atmosphere for hundreds of thousands of years. Researchers are now discussing the possibility of sampling this lake. Results on the Vostok ice core were presented at the American Geophysical Union's Spring Meeting May 20-24 in Baltimore. [Lynn Simarski]
SCIENTISTS STUDY MAJOR CONIFER FORESTS IN U.S. AND RUSSIAFor the past two years, scientists from Russia and the U.S. NSF's Long-Term Ecological Research program have been collaborating on a project that compares two major conifer forest regions of the globe. Its objective is to study vegetation in the St. Petersburg, Russia area, and in the western Washington and Oregon region of the U.S. Scientists are comparing carbon cycles through the conifer environment of these two areas, leading to a better understanding of carbon dioxide, (a so-called "greenhouse gas.") Both areas are dominated by coniferous vegetation, and their forests are major economic resources. They differ, however, in climate, potential productivity, and land-use history. The comparisons have already led to several conclusions. For example, the amount of carbon in St. Petersburg-area forests has increased over the last 30 years, whereas that of the Pacific Northwest has decreased over the same time period. Carbon distribution in the two regions differ, with much more carbon stored in peat in the St. Petersburg region than in the Washington-Oregon area. The scientists are continuing their analysis, and will soon have further results to report. [Cheryl Dybas]
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