-------- Original Message --------
Subject:        SILS Bulletin 09-06 ASTER GDEM Data
Date:   Tue, 7 Jul 2009 15:11:24 -0600
From:   Sheryle J Jackson <[log in to unmask]>
To:     undisclosed-recipients:;




SILS Information Bulletin

Number:  09-06 ASTER GDEM Data
Date:       July 07, 2009

The most complete terrain map of the Earth’s surface has been published
and is now available at *no charge* to users worldwide.

On June 29^th the Ministry of Economy, Trade, and Industry (METI) of
Japan and the United States National Aeronautics and Space
Administration (NASA) jointly released Version 1 of the Advanced
Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global
Digital Elevation Model (GDEM).  The ASTER GDEM is available to users
worldwide via electronic
download from the Earth Remote Sensing Data Analysis Center (ERSDAC) of
Japan and from NASA’s Land Processes Distributed Active Archive Center
(LP DAAC).

The data is comprised of 1.3 million images and the resulting Global
Digital Elevation Map covers 99% of the Earth’s surface. Previously the
most complete topographic map was NASA’s Shuttle Radar Topography
Mission which covers 80% of the Earth’s surface. “This is the most
complete, consistent global digital elevation data yet made available to
the world,” said Woody Turner, NASA program scientist on the ASTER mission

The ASTER instrument was built by METI and launched onboard NASA’s Terra
spacecraft in December 1999. It has an along-track stereoscopic
capability using its near infrared spectral band and its nadir-viewing
and backward-viewing telescopes to acquire stereo image data with a
base-to-height ratio of 0.6. One nadir-looking ASTER VNIR scene consists
of 4,100 samples by 4,200 lines, corresponding to about 60 km-by-60 km
ground area..

Initial studies to validate and characterize the ASTER GDEM confirm that
pre-production accuracy estimates are generally achieved for most of the
global land surface, although results do vary and true accuracies do not
meet pre-production estimates for some areas. In addition, Version 1 of
the ASTER GDEM does contain certain residual anomalies and artifacts
that affect the accuracy of the product and may be impediments to
effective utilization for certain applications. Consequently, METI and
NASA acknowledge that Version 1 of the ASTER GDEM should be viewed as
“experimental” or “research grade.” Nevertheless, they are confident
that the ASTER GDEM represents an important contribution to the global
earth observation community.

The ASTER GDEM data is distributed by USGS.  For more information
contact the LP DAAC staff at EROS 605-594-6116 or 866-573-3222*
**[log in to unmask]* <mailto:[log in to unmask]>*. *To obtain the
data* *users will need to register on the DAAC site (WIST)
 */_https://wist.echo.nasa.gov/~wist/api/imswelcome_/_/_*
<https://wist.echo.nasa.gov/%7Ewist/api/imswelcome/>*  * Product i*s
*titled* ASTER Global DEM.  *For more information on other products
distributed by USGS contact the Science and Information Library Services
at:1-888-ASK-USGS

Sheryle Girk-Jackson 303 202 4176, FAX 303 202 4633, email:
[log in to unmask] <mailto:[log in to unmask]>










Sheryle J. Girk-Jackson
Technical Information Specialist/Business Acquisitions
USGS/ESIC