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ASTER Website Update - April 2013
A report on the 42nd ASTER Science Team Meeting was published in the
March/April issue of The Earth Observer.
ASTER Website Update - February 2013
Updated the Full ASTER Bibliography (pdf 2.9 MB) on the Presentations and Documents page.
ASTER User
Notification - November 2012
In order to serve the Land Processes Distributed Active Archive Center (LP DAAC) user community more effectively,
the LP DAAC will transition from FTP to HTTP for ASTER and MODIS downloads on December 12, 2012. The HTTP updates
are designed to increase performance and improve security during data retrieval. Both FTP and HTTP capabilities
will be available through January 16, 2013. After January 16, only the HTTP option will be available. Users of
LP DAAC data should plan to update any automated scripts for LP DAAC data retrieval before the January 16, 2013 deadline.
ASTER Website Update - July 2012
Added the Full ASTER Bibliography (pdf 2.5 MB) to the Presentations and Documents page.
ASTER User
Notification - May 2012
The LP DAAC updated their ASTER Level 1 processing software with geometric correction database Version 3.02.
This correction, generated by the Earth Remote Sensing Division of Japan Space Systems, improves the
geolocation error in ASTER TIR nighttime observations. ASTER data processed through GDS IMS and the LP DAAC
uses the improved geometric correction DB Ver. 3.02. Further details are available in the
LP DAAC Software Update notice.
ASTER User
Notification - April 2012
The Terra website has a new look. Learn about the EOS
flagship satellite Terra and how its five onboard instruments provide insight into the total Earth system.
ASTER User
Notification - April 2012
As of March 30, 2012, the Earth Remote Sensing and Data Analysis Center (ERSDAC) merged with the
Institute for Unmanned Space Experiment Free Flyer (USEF) and the Japan Resources Observation System
and Space Utilization Organization (JAROS) to form a new organization called Japan Space Systems
(J-spacesystems). ERSDAC is now referred to as the
Earth Remote Sensing Division.
Activities and services previously carried out by ERSDAC, including the distribution of ASTER data,
will continued to be provided by the new organization.
ASTER User
Notification - March 2012
WIST has been retired and replaced by Reverb.
Should you have further questions about Reverb, please visit the Reverb Tutorial.
ASTER User
Notification - February 2012
Version 3 of the North American ASTER Land Surface Emissivity Database (NAALSED), developed at the Jet Propulsion Laboratory (JPL), is now available for download through
Reverb, LP DAAC Data Pool, and USGS
EarthExplorer (EE). NAALSED provides seamless emissivity data for use in climate research.
NAALSED is a collection of 3,327 1 degree by 1 degree tiles compiled from all clear ASTER "leaf on" season (July, August, September) data collected over North America
from 2000 to 2010. Each tile contains several layers of science data sets, including surface emissivity, temperature, and a top of atmosphere
Normalized Difference Vegetation Index (NDVI). Each tile also contains supplemental layers, such as a regional version of the ASTER GDEM resampled to 100 meters,
geographic coordinates, a land-water map, and the number of observations used as input. More information on NAALSED may be obtained from the
Joint Emissivity Database Initiative (JEDI) website and the
LP DAAC NAALSED Data Product Page.
ASTER User
Notification - October 2011
The Ministry of Economy, Trade, and Industry (METI) of Japan and the United States National Aeronautics and Space Administration (NASA) announced the release of the Version 2 ASTER Global Digital Elevation Model (GDEM) on October 17, 2011.
The Version 2 release features improved spatial resolution, increased horizontal and vertical accuracy, and superior water body coverage and detection. Version 2 ASTER GDEM data is available to users free of charge from
NASA Reverb, Land Processes Distributed Active Archive Center (LP DAAC) Global Data Explorer,
or Japan Space System's ASTER GDEM Page.
ASTER User
Notification - May 2011
All 11 years of ASTER Level-1B data over the U.S. and territories have been made available by the LP DAAC. Users may browse, search, and download their product(s) of interest from several sites.
The USGS EarthExplorer (EE) client at http://earthexplorer.usgs.gov is the newest.
The first step is to register for a free account. Then click on the "Data Sets" tab, expand "NASA LP DAAC Collections," and select ASTER. Next use the search criteria to choose location and time periods.
The data are also available from NASA Reverb, the USGS Global Visualization Viewer (GloVis),
and the LP DAAC Data Pool.
ASTER User
Notification - February 2011
As of February 2011, the LP DAAC Data Pool has eliminated the two-year rolling archive and expanded holdings to include data covering the U.S. and territories for the lifetime of the Terra
mission.
Data Pool holdings are available to the user at no cost.
ASTER Website Update - February 2011
Added the Full ASTER Bibliography (pdf 887 KB) to the Presentations and Documents page.
ASTER User
Notification - August 2009
As of August 2009, ASTER billable orders from non NASA affiliated users are no longer being accepted from the
Land Processes Distributed Active Archive Center (LP DAAC). Metadata search and browse imagery
continue to be available through Glovis
or Reverb.
Japan Space System's Ground Data System (GDS) IMS is available to provide billable ASTER products to non-NASA
affiliated users. Please contact LP DAAC
User Services for additional information.
ASTER User Notification - June 29, 2009
Japan's Ministry of Economy, Trade and industry (METI) and NASA announced the release of the ASTER Global Digital Elevation Model (GDEM) on June 29, 2009. The GDEM was created by stereo-correlating the 1.3 million scene ASTER VNIR archive, covering the Earth's land surface between 83N and 83S latitudes.
The GDEM is produced with 30 meter postings, and is formatted in 1 x 1 degree tiles as GeoTIFF files. Each GDEM file is accompanied by a Quality Assessment file, either giving the number of ASTER scenes used to calculate a pixel's value, or indicating the source of external DEM data used to fill the ASTER voids.
The GDEM is available for download from NASA Reverb and Japan Space System's ASTER GDEM Page.
Please refer to the Reverb GDEM ordering tutorial for guidance in placing an order through Reverb.
This ASTER product is available at no charge for any user pursuant to an agreement between METI and NASA. For more information about the GDEM, see the Validation Report: ASTER GDEM Validation Summary Report.
ASTER User
Advisory -
Change in Status Alert - January 12, 2009
ASTER SWIR detectors are no longer functioning due to anomalously high SWIR detector temperatures. ASTER SWIR data acquired since April 2008 are not useable, and show saturation of values and severe striping. All attempts to bring the SWIR bands back to life have failed, and no further action is envisioned. VNIR and TIR data continue to show excellent quality, meeting all mission requirements and specifications.
ASTER User
Advisory - Change in Status Alert - September 1, 2008
ASTER SWIR bands continue to be adversely impacted by an anomalously high
SWIR detector temperature. Although the ASTER team continues to focus on
this situation, no improvement is anticipated in the next few weeks. Users
are advised that ASTER SWIR data acquired from late April 2008 to the
present exhibit anomalous saturation of values and anomalous striping.
Cloud cover assessment and TIR location accuracy have also been affected.
Earlier archived data conform to mission specifications.
Additional advisories will continue to be provided.
ASTER User
Advisory - Change in Status Alert - May 7, 2008
Users are advised that ASTER SWIR data acquired in late April
and early May 2008 exhibit anomalous saturation of values and anomalous
striping. Cloud cover assessment and TIR location accuracy have also been
affected by the present situation.
Since January 2008, SWIR performance has been stable and data
quality has been nominal. On April 23, 2008, the SWIR detector temperature rose
precipitously, and SWIR Bands 5-9 saturated.
In an attempt to lower the SWIR detector temperature and improve
data quality, the ASTER Team plans to commence another SWIR recycling procedure
on May 7, 2008. If successful, stable SWIR performance and nominal data quality
will be restored.
The data quality impacts referenced in the April 9, 2008 alert
still apply for the periods specified.
Additional advisories will continue to be provided.
ASTER User
Advisory - February 5, 2008
This advisory is written to users of ASTER SWIR data to alert them to the
fact that some anomalous saturation of values has been observed in ASTER Bands 5
through 9 since May 2007. This problem is attributed to an increase in ASTER SWIR detector temperature believed to be caused by increased thermal resistance
in the SWIR cryocooler. VNIR and TIR bands are unaffected by this problem.
The slow increase in SWIR detector temperature did not become a problem until
early in 2007, and it did not really affect data quality until the detector
temperature exceeded 83 K. Figure 1 shows the trend in SWIR detector temperature
for the past year. Note that the detector temperature first exceeded 83 K on about May 1, 2007.
Following that date, four attempts have been made to lower the detector
temperature by recycling the cryocooler, including increasing the stroke length
of the cryocooler piston. The first attempt in May succeeded in reducing the
temperature to 82 K, but the temperature soon began to increase again, exceeding
83 K in late July. Second and third attempts to reduce the SWIR detector
temperature essentially failed in October. However, a fourth attempt in
mid-January, 2008 succeeded in reducing the SWIR detector temperature to 83 K.
Since that date the SWIR detector temperature has remained stable at 83 K.
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Figure 1. ASTER SWIR detector narrow temperature trend. Maximum (red),
average (black), and minimum (green) lines are plotted. |
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As long as the detector temperature remains at 83 K, little or no degradation of
ASTER SWIR data is expected. However, users are advised that for ASTER SWIR data
collected between late May 2007 and late January 2008, the SWIR detector
temperature exceeded 83 K, except for about six weeks in June and July. SWIR
data acquired during these periods may exhibit anomalous saturation of values,
particularly at high sun angles and for materials that are highly reflective in
the SWIR bands.
Figure 2 shows an example of SWIR saturation in an extremely bright desert
scene acquired over northern Africa in August 2007, when the detector
temperature was at about 83.5 K. Saturation is especially prevalent in Bands 5,
6, and 7. Saturated pixels with DN = 255 are displayed in black. All other
colors are unsaturated pixels.
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Figure 2. SWIR saturation example. August 24, 2007 Africa observation. Pixels
with DN = 255 are colored black. |
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