[Yahoo＠tw_NEWS] 美國宇航局概述地球淡水分布新變化
http://tw.news.yahoo.com/article/url/d/a/061212/54/7xu8.html
新聞來源：美通社(PR_Newswire)華盛頓電
由 Gravity Recovery and Climate Experiment（重力研究和氣候試驗，簡稱 GRACE
）計劃實施的最新淡水儲量太空觀測提供了一幅地球最寶貴的自然資源全球分布和變
化方式的新畫面。
研究者們利用 GRACE 近5年的數據記錄來估計覆蓋大部分地球陸地區域的50多個河流
流域的季節性水儲量變化。這一變化反映了儲存於河流、湖泊、水庫；澇原上的冰雪
；以及土壤和蓄水層中的水量變化。
位於歐文的加利福尼亞大學 (University of California) Earth System Science（
地球繫統科學研究所）教授 Jay Famiglietti 表示：“ GRACE 提供了一種前所未有
的大陸淡水儲量觀點。利用更長的時間，我們能將長期趨勢與自然的季節性變化區分
開來，並對水的可用性響應自然氣候變化和氣候改變的方式進行跟蹤。”
一些非洲流域，如剛果河、贊比西河和尼羅河，在過去５年裡出現了重大的干涸現像
。而在美國，密西西比河與科羅拉多河流域的水儲量卻在這段時間裡出現了增長。這
一信息對於管理非洲和東南亞的脆弱地區來說是至關重要的，因為不斷增長的人口和
生活水平的提高對水資源產生了需求，而這一資源經常是供不應求的。這一數據可用
來制訂更具信息性的地區水資源管理決策。
這兩顆 GRACE 衛星對地球重力場的月度微小變化進行了監測。 這種變化主要是由地
球上的陸地、 海洋、 冰川和大氣蓄水層中的水運動引起的。水文學者正在對 GRACE
數據進行分析，以確定降水量變化、地下水損耗以及雪和冰川融化速度的可能趨勢，
並了解它們的根本原因。
美國宇航局 (NASA) 位於馬裡蘭州格林貝爾特的戈達德航天飛行中心(Goddard Space
Flight Center) 的水文學者 Matt Rodell 表示，GRACE 數據與地面觀測的數據非常
一致。 因此，水文學者現在可以將 GRACE 數據應用於那些將影響地區性水管理的途
徑中。他說：“GRACE 數據增進了我們對水循環的了解，並改進了在計算機模型中對
土壤水分、雪和地下水的模擬。這是更好地預測全球氣候、水流、洪水、乾旱和水資
源過程中邁出的重要一步。”
美國宇航局位於加州帕薩迪納的噴氣推進實驗室 (Jet Propulsion Laboratory ) 的
GRACE 計劃科學家 Michael Watkins 則表示， Grace 是美國宇航局廣泛的水循環研
究計劃中唯一一個測量所有水儲量變化的計劃。他說：“GRACE 探測的是從地表到地
球最深蓄水層的水儲量變化，所有的水都在它的研究範圍之內。”
GRACE 探測水的能力對於新興的地下水遙感領域來說尤其重要。Famiglietti 指出：
“地下水遙感一直是水文學家的未解之迷，因為它藏於地表之下，大多傳感器都探測
不到。除美國和其他幾個發達國家之外，其他國家未能很好地對水進行監測。據推測
，由於過度開采，很多地球蓄水層正趨於衰竭。但是缺乏數據又租礙了量化蓄水層變
化以及采取必要措施阻止其耗盡的努力。憑借更多的數據，如對地表水和土壤水分的
測量，我們可以利用 GRACE 來解決這個問題。”
消息來源 美國宇航局
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[JPL] NASA Outlines Recent Changes in Earth's Freshwater Distribution
http://www.nasa.gov/centers/jpl/news/grace-20061212.html
[NEWS_Release] (標題同上)
http://www.nasa.gov/home/hqnews/2006/dec/HQ_06370_GRACE_prt.htm
新聞來源：1.NASA > JPL > NEWS (有附圖)
2.NASA (無附圖)
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.
[圖片]
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.
[延伸閱讀]
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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