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<tt>Dear GLIMS colleagues,</tt>
<p><tt>Now that GLIMS ASTER data are finally beginning to get acquired
and</tt>
<br><tt>make their way to the USA, we want to offer a status report and
some</tt>
<br><tt>guidance on finding, ordering, and using ASTER data.</tt>
<br>
<p><tt>STATUS</tt>
<br><tt>As of January 21, over 50,090 data granules were available
in the</tt>
<br><tt>ASTER database at EDG (EOS Data Gateway). Several granules
may</tt>
<br><tt>represent reprocessed versions of the same acquisition date and
times,</tt>
<br><tt>so there is some repetition in the EDG database. Approximately
2500</tt>
<br><tt>daytime ASTER granules over glaciers are listed. Of the glacier</tt>
<br><tt>granules, only 76 are the cleaned up and geometrically corrected
L1B</tt>
<br><tt>data. Of those, 43 were acquired with the proper gain settings
for snow</tt>
<br><tt>and ice. Most of the glacier data were acquired in stereo
mode (both</tt>
<br><tt>band 3N and 3B).</tt>
<br>
<p><tt>FINDING DATA</tt>
<br><tt>Thanks to extra efforts by EDC (EROS Data Center), the U.S.</tt>
<br><tt>Geological Survey in Flagstaff has begun to download weekly updates
of</tt>
<br><tt>listing of all ASTER data received by the EDG. We then
parse and</tt>
<br><tt>spatially search the database within ArcView and IDL to produce
a list</tt>
<br><tt>and maps of ASTER data over glaciers. We have place the search
results</tt>
<br><tt>on our GLIMS distribution protected website</tt>
<p><tt>(<a href="http://wwwflag.wr.usgs.gov/GLIMS/usgsdist/main.html">http://wwwflag.wr.usgs.gov/GLIMS/usgsdist/main.html</a>)</tt>
<p><tt>The userid and passwd are: glimsguest ber1ng789</tt>
<br>
<p><tt>The queries are provided to our GLIMS colleagues as a</tt>
<br><tt>comma-delimited list of data granules sorted by regional center
number</tt>
<br><tt>(RC#). Information about the regional centers is listed in
the procrc.tab</tt>
<br><tt>on the above website or on the public GLIMS website:</tt>
<p><tt><a href="http://wwwflag.wr.usgs.gov/GLIMS/collaborators.html">http://wwwflag.wr.usgs.gov/GLIMS/collaborators.html</a></tt>
<p><tt>At this stage, the cloud assessment provided by the ASTER processing</tt>
<br><tt>is still very unreliable over snow and ice. We are working
with EDC to</tt>
<br><tt>improve the cloud and quality assessment using MODIS data.
For</tt>
<br><tt>now,the lists we provide will be data dumps sorted by area that
are</tt>
<br><tt>filtered by appropriate gains and sun angles. You will
see many entries</tt>
<br><tt>with either 0% clouds or 100% clouds while the browse images will</tt>
<br><tt>show just the opposite situation. It will be up to each Regional
Center</tt>
<br><tt>and/or steward to search the EDG and assess the browse images before</tt>
<br><tt>ordering.</tt>
<p><tt>We've posted a table on the website (procrc.tab) that contains scene</tt>
<br><tt>statistics for all glacier areas and each Regional Center. The
first is a</tt>
<br><tt>block for all ASTER scenes for which we have been able to get</tt>
<br><tt>information from EDC and that fall in glacier areas(see below).
This is</tt>
<br><tt>followed by a block for each RC.</tt>
<p><tt> File=../GLIMS/searches/glacierbyregion_oct1-jan21_2001.csv</tt>
<br><tt># scenes: total, 1A, 1B, other= 2499 2424
75 0 GLIMS=1104</tt>
<br><tt> OFF HIGH
NORM LOW Low1 Low2 ON</tt>
<br><tt> Sub 0 1
2 3 4
5 6</tt>
<br><tt> VNIR 9 1041 1409
40 0 0
0</tt>
<br><tt> 3aft 9 20
2430 40 0
0 0</tt>
<br><tt> SWIR 9 1143 1335
0 0 12
0</tt>
<br><tt> TIR 0 0
0 0 0
0 2499</tt>
<br><tt>----------------------------------------------------------</tt>
<p><tt>For each Region (separated by dashed line), the first four lines
list</tt>
<br><tt>the region number, the geographic region and RC information. The
5'th</tt>
<br><tt>line contains the name of the inventory file used. The 6'th line
lists</tt>
<br><tt>the total number of ASTER scenes in the region, the number that
are</tt>
<br><tt>Level-1A, the number that are Level-1B, the number of other processing</tt>
<br><tt>levels (typically zero) and the number with the ASTER gains set
for</tt>
<br><tt>GLIMS (VNIR='NORM', SWIR ='HIGH'. This is followed by a little</tt>
<br><tt>table of the statistics of Gain settings.</tt>
<p><tt>We have made individual files for each RC that list the ASTER images</tt>
<br><tt>in their areas. Files contain one line for each image, with
the data from</tt>
<br><tt>EDC in comma delimited form. The files have with names RCnn.tab</tt>
<br><tt>where nn is the RC number. There are some images listed for
every</tt>
<br><tt>Region.</tt>
<br>
<p><tt>ORDERING ASTER DATA</tt>
<br><tt>ASTER data is now publically available online, for free, at the
EOS Data</tt>
<br><tt>Gateway:</tt>
<p><tt><a href="http://edcimswww.cr.usgs.gov/pub/imswelcome/">http://edcimswww.cr.usgs.gov/pub/imswelcome/</a></tt>
<p><tt>You may log in as guest (though its better to register since it
then</tt>
<br><tt>remembers your settings) and choose ASTER L1A and/or L1B as your</tt>
<br><tt>datasets. Then search on the start times provided in our GLIMS
search</tt>
<br><tt>results or on the lat/long coordinates. When you find
images that match</tt>
<br><tt>your criteria and have acceptable browse images, add them to your</tt>
<br><tt>shopping cart and complete the order. You may receive the
data either</tt>
<br><tt>via FTP or on 8mm tapes from EDC.</tt>
<br>
<p><tt>USING ASTER DATA</tt>
<br><tt>The data you receive from EDC will be in HDF-EOS format, a fairly</tt>
<br><tt>complex NASA format that's described in several places on the web.</tt>
<br><tt>There are a variety of free and commercial applications to view
the</tt>
<br><tt>HDF-EOS data. You might get started with a free viewer
called</tt>
<br><tt>"WebWinds" that may be downloaded from JPL (refer to</tt>
<br><tt><a href="http://webwinds.jpl.nasa.gov/">http://webwinds.jpl.nasa.gov/</a>).
WebWinds will also let you save the</tt>
<br><tt>data in a simpler format. The newest versions of ENVI, which
is a</tt>
<br><tt>commercial package that uses IDL (see <a href="http://www.rsinc.com/">http://www.rsinc.com/</a>),
can also</tt>
<br><tt>read HDF-EOS (this is not an endorsement by the USGS).
Our group</tt>
<br><tt>(mostly Jim Torson) is developing a useful image viewer with
some basic</tt>
<br><tt>analysis tools that uses IDL on UNIX systems. The viewer,
CV, is</tt>
<br><tt>currently part of a larger set of image processing software called
ISIS.</tt>
<br><tt>A new HDF-EOS compatible version of CV that does not require ISIS</tt>
<br><tt>is not yet available in the public release of ISIS. We will
notify you</tt>
<br><tt>when it's available. More information is available at</tt>
<br><tt><a href="http://wwwflag.wr.usgs.gov/ISIS">http://wwwflag.wr.usgs.gov/ISIS</a></tt>
<p><tt>ASTER data is available in two basic forms: L1B and L1A. For
most</tt>
<br><tt>applications, L1B is ASTER data in its most useful form.
L1B data</tt>
<br><tt>have been cleaned up and geometrically corrected in Japan.
The most</tt>
<br><tt>recent examples that we have examined so far appear to have only
minor</tt>
<br><tt>defects. Overall, L1B is much easier to use than L1A since
no</tt>
<br><tt>pre-processing is required.</tt>
<p><tt>L1A data represents a nearly raw version of the ASTER instrument
data.</tt>
<br><tt>As a result, L1A data usually have image striping and band to band</tt>
<br><tt>misregistration. VNIR bands 1 and 2 are usually reasonably
good while</tt>
<br><tt>bands 3N and 3B have even/odd stripes. SWIR bands 4-9 are
not</tt>
<br><tt>registered in L1A data. TIR bands 10-14 are generally useable,
though</tt>
<br><tt>somewhat striped in L1A.</tt>
<p><tt>If you find some useful images that are only available in L1A data,we</tt>
<br><tt>may be able to clean up and register a few scenes for you in Flagstaff
by</tt>
<br><tt>special request. We have developed IDL applications that
will destripe</tt>
<br><tt>and register the data. This quick registration is a shift
of an entire band</tt>
<br><tt>image by an integral number of lines and samples; it does not involve</tt>
<br><tt>resampling, so the original resolution is not changed. This registration
will</tt>
<br><tt>leave parts of the images, probably the corners, out of registation
by up</tt>
<br><tt>to a few pixels.We do not have an efficient way to perform a geometric</tt>
<br><tt>correction yet.</tt>
<p><tt>If you have any questions, we would be glad to assist you through
your</tt>
<br><tt>appropriate Regional Centers.</tt>
<p><tt>Thank you and happy hunting.</tt>
<p><tt>Sincerely,</tt>
<br><tt> The US Geological Survey - Flagstaff GLIMS TEAM</tt>
<p><tt>+++++++++++++++++++++++++++++++++++++++++++++++++++++</tt>
<br><tt>Rick Wessels
rwessels@flagmail.wr.usgs.gov</tt>
<br><tt>U.S. Geological Survey Phone
(520)-556-7022</tt>
<br><tt>2255 N. Gemini Drive
FAX
-7014</tt>
<br><tt>Flagstaff, AZ 86001
Main Office -7000</tt>
<br><tt>+++++++++++++++++++++++++++++++++++++++++++++++++++++</tt>
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