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May 12, 2003
Unique NASA Satellite Watches Rainfall from Space
Your local weather forecaster uses Doppler radar systems, covering U.S.
regions, to estimate rainfall and flooding, but NASA research satellites
can see rainfall worldwide.
Data from NASA's Tropical Rainfall Measuring Mission (TRMM) satellite,
along with information from other satellites, allows researchers to see
how much rain is falling over most of the world every three hours. This
capability enables scientists to daily map areas of potential flooding.
These maps, available to the public on the Internet, will help water
resource managers and scientists around the world by providing near-real
time data of rainfall and flood potential. TRMM is considered a unique "rain
gauge in the sky," because its instruments can look into clouds to determine
rainfall, while other satellites can only see flooded areas after floods
have occurred.
Because of its extraordinary capability, TRMM is used to calibrate and
fine-tune measurements of rainfall taken by other satellites, leading
to current updated records on a global scale. Once baselines are established,
researchers use the higher quality TRMM data wherever possible and fill
in the gaps with data from other satellites to get a more complete picture
of rainfall around the world.
"This ability to detect potential floods is extremely useful for disaster
monitoring," said Robert Adler, TRMM Project scientist at the Goddard
Space Flight Center, Greenbelt, Md. "The rainfall maps are also useful
in assessing the state of crops in remote regions, especially in the
tropics," he said.
Maps that show areas of potential floods use precipitation radar data
and high-resolution measurements of water content of clouds made by microwave
radiometers. The maps span the Earth from 50 degrees north latitude to
50 degrees south latitude (an area just north of the U.S.-Canadian border
and south to the tip of Argentina).
There are three variations of the rainfall accumulation maps, including
24-hour maps showing areas where more than 35 mm (1.37 inches) of rain
has accumulated; maps with three-day accumulations of more than 100 mm
(3.93 inches); and maps depicting areas with weeklong accumulations of
more than 200 mm (7.87 inches).
Another map product, updated every three hours, shows a global snapshot
of rainfall. A seven-day "movie loop" of the images allows users to track
storms as they travel over land and oceans around the globe. Researchers
use these near- global rainfall maps to monitor formation and dissipation
of El Nino/Southern Oscillation conditions, soil moisture, and ocean
salinity. These maps also are useful to water resource managers and farmers
around the world.
The Adler led team of NASA scientists produced these TRMM rainfall and
flood potential maps. The maps merge data from the TRMM Microwave Imager
Precipitation Radar with information from other microwave satellites
and geosynchronous weather satellite infrared data. Exploiting the strengths
of multiple data sources increases the accuracy of the maps.
TRMM is a joint U.S.-Japanese mission and part of NASA's Earth Science
Enterprise, a long-term research program designed to study the Earth's
land, oceans, air, ice and life as a total system. The TRMM satellite
was launched on November 27, 1997.
NASA's Earth Science Enterprise is dedicated to understanding the Earth
as an integrated system and applying Earth System Science to improve
prediction of climate, weather and natural hazards, using the unique
vantage point of space.
For information and TRMM images on the Internet, visit:
http://www.gsfc.nasa.gov/topstory/2003/0425floods.html
For information about TRMM rain and flood maps on the Internet, visit:
http://trmm.gsfc.nasa.gov/
For information about NASA and Earth Science projects on the Internet, visit:
http://www.nasa.gov
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Contacts:
Krishna Ramanujan
Goddard Space Flight Center, Greenbelt, Md.
301-286-3026
kramanuj@pop900.gsfc.nasa.gov
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Spring Flooding in the Southeast
Data from TRMM and other satellites estimated more than
16 inches of rain fell in the red areas of the top map (TN, AL, GA) from
May 4-9, 2003 from spring storms. Credit: Hal Pierce/Jeff Halverson,
NASA Goddard Space Flight Center
High
Resolution Image
Southeast Flood Rainfall Statistics
Left graph shows rain fell as much as 35 mm (1.4 inches)
per hour over the 5 day period. Right graph shows that after 85 hours,
rain totaled 472.7 mm (18.6 inches) within a 200 km (77 mile) radius
surrounding Nashville, TN. Credit: Hal Pierce/Jeff Halverson, NASA Goddard
Space Flight Center
High
Resolution Image
Global Flood Potential Map, May 2, 2003
Red regions on this map show areas that have received
a 24-hour rainfall accumulation greater than 1.5 inches.� These flood
potential maps are generated for 1-day, 3-day and 7-day time periods
and are available on the TRMM website. Credit: Hal Pierce, NASA Goddard
Space Flight Center
High
Resolution Image
Flooding in Brazil, January 21, 2003
This dramatic image captures a week's worth of torrential
rainfall over a small region near Belo Horizonte, Brazil, where the death
toll from mudslides has been climbing. Mudslides developed in the mountainous
terrain of the Brazilian Highlands where runoff from up to sixteen inches
of rain swept through hillside villages. This is more rain than Denver,
Colorado or Los Angeles, California receive in an entire year. The image
was created using a technique that combines data from NASA's Tropical
Rainfall Measurement Mission (TRMM) with other rainfall-measuring satellites
(from NASA's Earth Observatory Website). Red regions have received
over 14 inches of rainfall. Credit: Hal Pierce, NASA Goddard Space Flight
Center
Flooding in Western Australia, January 23rd to 25th, 2003
Heavy seasonal rains recently fell over a small region
of Western Australia from January 23rd to the 25th. While rainfall normally
occurs this time of year as part of the southern summer monsoon trough,
several large, organized cloud clusters bearing heavy rains moved eastward
off the Indian Ocean during a 48-72 hour period, sweeping over the same
region. The portion of the country receiving the heavy rains is also
mountainous (the Hamersley Range), which may have contributed to the
flooding by focussing heavy downpours over small regions, and concentrating
the runoff into narrow stream valleys. The image shows the isolated nature
of the rain accumulation over a nine day period starting on January 20,
2003. Local area accumulations approaching twenty inches are indicated
on the rainmap, which was created using data from NASA's Tropical Rainfall
Measurement Mission (TRMM) satellite combined with data from other rain
measuring satellites. The heavy rains followed a year-long drought in
this region, which was also ravaged by severe wildfires, and washed out
roads connecting small towns (from
NASA's
Earth Observatory Website).
Red regions have received over 20 inches of rainfall. Credit: Hal Pierce,
NASA Goddard Space Flight Center
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