[Yahoo＠tw_NEWS] 美国宇航局概述地球淡水分布新变化 http://tw.news.yahoo.com/article/url/d/a/061212/54/7xu8.html 新闻来源：美通社(PR_Newswire)华盛顿电 由 Gravity Recovery and Climate Experiment（重力研究和气候试验，简称 GRACE ）计划实施的最新淡水储量太空观测提供了一幅地球最宝贵的自然资源全球分布和变 化方式的新画面。 研究者们利用 GRACE 近5年的数据记录来估计覆盖大部分地球陆地区域的50多个河流 流域的季节性水储量变化。这一变化反映了储存於河流、湖泊、水库；涝原上的冰雪 ；以及土壤和蓄水层中的水量变化。 位於欧文的加利福尼亚大学 (University of California) Earth System Science（ 地球系统科学研究所）教授 Jay Famiglietti 表示：“ GRACE 提供了一种前所未有 的大陆淡水储量观点。利用更长的时间，我们能将长期趋势与自然的季节性变化区分 开来，并对水的可用性响应自然气候变化和气候改变的方式进行跟踪。” 一些非洲流域，如刚果河、赞比西河和尼罗河，在过去５年里出现了重大的干涸现像 。而在美国，密西西比河与科罗拉多河流域的水储量却在这段时间里出现了增长。这 一信息对於管理非洲和东南亚的脆弱地区来说是至关重要的，因为不断增长的人口和 生活水平的提高对水资源产生了需求，而这一资源经常是供不应求的。这一数据可用 来制订更具信息性的地区水资源管理决策。 这两颗 GRACE 卫星对地球重力场的月度微小变化进行了监测。 这种变化主要是由地 球上的陆地、 海洋、 冰川和大气蓄水层中的水运动引起的。水文学者正在对 GRACE 数据进行分析，以确定降水量变化、地下水损耗以及雪和冰川融化速度的可能趋势， 并了解它们的根本原因。 美国宇航局 (NASA) 位於马里兰州格林贝尔特的戈达德航天飞行中心(Goddard Space Flight Center) 的水文学者 Matt Rodell 表示，GRACE 数据与地面观测的数据非常 一致。 因此，水文学者现在可以将 GRACE 数据应用於那些将影响地区性水管理的途 径中。他说：“GRACE 数据增进了我们对水循环的了解，并改进了在计算机模型中对 土壤水分、雪和地下水的模拟。这是更好地预测全球气候、水流、洪水、乾旱和水资 源过程中迈出的重要一步。” 美国宇航局位於加州帕萨迪纳的喷气推进实验室 (Jet Propulsion Laboratory ) 的 GRACE 计划科学家 Michael Watkins 则表示， Grace 是美国宇航局广泛的水循环研 究计划中唯一一个测量所有水储量变化的计划。他说：“GRACE 探测的是从地表到地 球最深蓄水层的水储量变化，所有的水都在它的研究范围之内。” GRACE 探测水的能力对於新兴的地下水遥感领域来说尤其重要。Famiglietti 指出： “地下水遥感一直是水文学家的未解之迷，因为它藏於地表之下，大多传感器都探测 不到。除美国和其他几个发达国家之外，其他国家未能很好地对水进行监测。据推测 ，由於过度开采，很多地球蓄水层正趋於衰竭。但是缺乏数据又租碍了量化蓄水层变 化以及采取必要措施阻止其耗尽的努力。凭借更多的数据，如对地表水和土壤水分的 测量，我们可以利用 GRACE 来解决这个问题。” 消息来源 美国宇航局 ---------------------------------------------------------------------------- [JPL] NASA Outlines Recent Changes in Earth's Freshwater Distribution http://www.nasa.gov/centers/jpl/news/grace-20061212.html [NEWS_Release] (标题同上) http://www.nasa.gov/home/hqnews/2006/dec/HQ_06370_GRACE_prt.htm 新闻来源：1.NASA > JPL > NEWS (有附图) 2.NASA (无附图) Recent space observations of freshwater storage by the Gravity Recovery and Climate Experiment (Grace) are providing a new picture of how Earth's most precious natural resource is distributed globally and how it is changing. Researchers are using the mission's almost five-year data record to esti- mate seasonal water storage variations in more than 50 river basins that cover most of Earth's land area. The variations reflect changes in water stored in rivers, lakes and reservoirs; in floodplains as snow and ice; and underground in soils and aquifers. " Grace is providing a first-ever look at the distribution of freshwater storage on the continents, " said Dr. Jay Famiglietti, professor of Earth System Science, University of California, Irvine. " With longer time series, we can distinguish long-term trends from natural seasonal vari- ations and track how water availability responds to natural climate vari- ations and climate change." Several African basins, such as the Congo, Zambezi and Nile, show signif- icant drying over the past five years. In the United States, the Missi- ssippi and Colorado River basins show water storage increases during that time.Such information is vital for managing water resources in vulnerable parts of Africa and Southeast Asia, since increasing populations and standards of living place demands on water resources that are often unsu- stainable. The data can be used to make more informed regional water- management decisions. The twin Grace satellites monitor tiny month-to-month changes in Earth's gravity field that are primarily caused by the movement of water in Earth's land, ocean, ice and atmosphere reservoirs. Hydrologists are ana- lyzing Grace data to identify possible trends in precipitation changes, groundwater depletion and snow and glacier melt rates, and to understand their underlying causes. Dr. Matt Rodell, a hydrologist at NASA's Goddard Space Flight Center, Greenbelt, Md., said the data correspond well with ground observations. As a result, hydrologists can now apply Grace data in ways that will impact regional water management. "Grace data improve our understanding of the water cycle and simulations of soil moisture, snow and groundwater in computer models, " he said. " This is a key step toward better weather, stream flow, flood, drought and water resource forecasts worldwide." Dr. Michael Watkins, Grace project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., said Grace is the only element in NASA's broad water cycle research program that measures changes in all types of water storage. " Grace detects water storage changes from Earth's surface to its deepest aquifers. Water can't hide from it," he said. The mission's abilities to detect water are particularly vital for the emerging field of groundwater remote sensing. " Remote sensing of ground- water has been a Holy Grail for hydrologists because it is stored beneath the surface and is not detected by most sensors, " said Famiglietti. "Out- side of the United States and a few other developed nations, it is not well monitored. It's been speculated that many of Earth's key aquifers are being depleted due to over-exploitation, but a lack of data has hampered efforts to quantify how aquifer levels are changing and take the steps necessary to avoid depleting them. With additional data, such as measure- ments of surface water and soil moisture, we can use Grace to solve this problem." Grace is also allowing scientists to estimate another key component of the water cycle for the first time: water discharged by freshwater streams from Earth's continents. Stream flow measurements are often not shared for economic, political or national defense reasons. Grace measurements of the total water discharged by continental streams are important for monitoring the availability of freshwater and understanding how surface water runoff from continents contributes to rises in global sea level. Scientists from NASA and the University of California, Irvine, are pre- senting their research today during the American Geophysical Union meeting in San Francisco. Grace is a partnership between NASA and the German Aerospace Center (DLR). The University of Texas Center for Space Research, Austin, has overall mission responsibility. JPL developed the two Grace satellites. DLR pro- vided the launch, and the GeoForschungsZentrum Potsdam, Germany, operates the Grace mission. [图片] www.nasa.gov/centers/jpl/images/content/164077main_grace-20061212-200.jpg Grace measurement of Mississippi River basin water storage, June 2004. Da- ta at this scale are useful for water cycle and climate studies. [Image credit: NASA/JPL] www.nasa.gov/centers/jpl/images/content/164083main_grace-20061212-combined -200.jpg When merged with computer models, Grace water storage data can be used for water resources and agricultural applications. [Image credit: NASA/JPL] www.nasa.gov/centers/jpl/images/content/164318main_watercycle-browse.jpg This image and animation demonstrate the major components of the global water cycle, and show how these components contribute to regulating the cycling of water in our environment. [Credit: NASA/GSFC] www.nasa.gov/centers/jpl/images/content/164320main_watercycle-missions-bro wse.jpg A diagram showing NASA missions involved in water cycle research. [延伸阅读] For more information about Grace, see www.csr.utexas.edu/grace/ . For more on NASA water and energy cycle research, visit watercycle.gsfc.na sa.gov/index.php. Other media contacts : Margaret Baguio, University of Texas Center for Space Research, Austin, 512-471-6922; Jennifer Fitzenberger, University of California, Irvine, 949-824-3969. ---------------------------------------------------------------------------- --

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