GLIMS Update: Global ASTER imaging reprioritization

[Gordon Hamilton]

Hey Jeff--

well, you sure know how to start a discussion! As one of the high latitude
GLIMSers, let me add my two pesos -- we can talk more at the workshop
this week (remind me, when is it? Tuesday or Wednesday evening?) and again
at the team meeting next week, but suffice it to say now, I don't think
it is realistic to scale back or eliminate high latitude scene acquisitions.
There is simply too much good science to be lost if such a plan is carried
out. A simple look at scene statistics does not tell the whole story --
in Greenland, for example, where we have been doing a lot of work recently,
there does seem to be a large number of cloud-free scenes. But for our
applications (quantitative change detection, such as velocity mapping and
repeat DEM comparisons), only a small proportion of these scenes turn out
to be useful (because of things like imaging geometry, presence of thin
cirrus clouds, etc.). In other words, we are stuggling to do some of our
core tasks because of a lack of *usable* imagery, too.

I have another suggestion that we might pursue with NASA managers and
ASTER ops people next week: we continue to use ASTER for high latitude
scene acquisitions (as long as the Japanese remain willing to do off-nadir
pointing), but push for NASA to do a commercial data buy of Ikonos, 
Quickbird, Digital Globe, etc. imagery for smaller mid/low latitude
glaciers. The commercial products would continue to be available under
the current pricing system (no-cost of $55/scene). Some arguments in
support of this idea:
- ASTER is one of the few sensors capable of imaging the far northern
and southern parts of the planet
- swath widths of ASTER are decent for the large glaciers we study in
these regions (i.e., a 65 x 65 km scene covers most, but sometimes not
all, of a polar glacier)
- smaller swaths of commercial data (10 x 10 km if I remember correctly)
might be well suited to the usually smaller ice masses in the low/mid
latitudes
- improved spatial resolution of commercial data would also be
advantageous for studying smaller glaciers.
Granted, it might be necessary to stitch together several commercial
scenes to cover an alpine ROI, but at least the data will be good.

Anyway, just another suggestion for us to discuss. It's not perfect
and there are probably a lot of downsides that I haven't thought
about, but it might be a way of keeping us all happy and doing good
science.

See you soon,

-gordon




-- 
Gordon Hamilton, Assoc. Professor Climate Change Institute University 
of Maine, Orono, ME 04469 gordon.hamilton at maine.edu 207-581-3446 
(ph/voicemail) 207-581-1203 (fax)