GLIMS ASTER image acquisition planning

Sun May 24 09:40:39 MDT 2009

Jeff--

I am just back from East Greenland, so I am jumping into this discussion
a bit late. Also, I will be heading back to Greenland in a few weeks, so
regrettably I will not be at the team meeting in Kyoto. Slawek raises a
very important point and it needs a thorough discussion.

Examining the number of scene acquisitions per year over Greenland (and/or
Antarctica) is a very crude way of determining the success of ASTER and/or
GLIMS imaging in these incredibly important parts of the glacierized world.
Bill just sent me a quick analysis of scene numbers/usability for the last
few years over selected parts of Greenland. Sure, some years have a lot of
image acquisitions (e.g., 400 scenes for the NE quadrant of Greenland in
2006) but the vast majority of these images are unusable for any kind of
quantitative analysis, such DEM generation, velocity mapping, melt pond
depth extraction, or margin mapping (e.g., for the same quadrant in 2006,
only ~15 images out of the 400 were somewhat usable).

A lot of the most important glaciers in Greenland (e.g., Kangerdlugssuaq,
Helheim) have *no* useable images in recent years (2007, 2008), which means
we have been unable to use ASTER to track the behavior of some of the key
glaciers contributing to sea level rise (we have had much better success
with ALOS data).

The same is true for a lot of Antarctica outlet glaciers -- our recent work
has relied on ALOS acquisitions to maintain data continuity.

My own attempts at Greenland STARs have been a total bust. Maybe my requests
were overrided by the GLIMS STAR?

I am not sure I have any good solutions. Going back to the beginnings of
the GLIMS program, the idea of collecting at least one usable image of each
glacier on Earth for the ~2000-timeframe has largely been accomplished. A
lot of these images are ASTER scenes, but the availability of high-resolution
optical imagery has exploded since the days when the GLIMS idea was hatched,
so a lot of the scenes are non-ASTER images. My guess is that the existing
image archive is sufficient for a lot of GLIMS tasks (e.g., mapping changes
in snow/ice extent) -- the small size of many mid-latitude ice masses
necessitates the need for a long time record in order to detect change; in
these cases, annual coverage is not required. The polar regions are different.
The changes are bigger and happening faster, and the consequences have global
implications. A lot of the really cool and high-profile science done by ASTER
has been in Greenland and Antarctica (I'm trying not to be biased here!), but
we have really been struggling to keep that science going with the current
acquisition plan.

Maybe we need to critically review the GLIMS objectives, see if the current
image archive (be it ASTER or any other easily-available high-resolution
imagery) is sufficient to meet that objective (and see where it does not meet
that objective), then re-assess what key science questions we want to be
trying to answer. The GLIMS idea is more than a decade old -- science has
evolved, and maybe other glaciological questions provide a better use of the
finite ASTER resource. Maybe not, but I think we need to take a close look
to be sure.

Okay, a long message, but I just wanted to echo Slawek's concerns.

-gordon

Quoting Jeffrey Kargel <jeffreyskargel at hotmail.com>:
>
> Slawek,
> I offer this letter as an open message to the GLIMS community   
> (responding to your message below) in a bid to enlist the GLIMS   
> community's further help in evaluating the successes and failures of  
>  the GLIMS STAR in the Southern Hemisphere in 2009, with recognition  
>  that what elapsed there (successes and failures) is apt to be a   
> model of what will happen this year in the Northern Hemisphere over   
> the next few months.  This is needed, while also recognizing that we  
>  need good Greenland coverage, as you are shooting for.  Perhaps  
> what  we need is a one-year Greenland DAR that supplements the  
> coverage  expected from the GLIMS STAR by targeting possibly  
> one-fifth of the  Greenland coastline for multiple repeat imaging  
> (that's in addition  to the current plan to get one image on average  
> of each part of the  coastline over the course of the summer).  I  
> would need to know what  one-fifth to cover with greater frequency,  
> and then we could see how  this idea fares with ASTER MIssion  
> Operations.
> So far as what has actually been achieved for GLIMS STARs of   
> non-Greenland/non-Antarctic glaciers, I can say we're still   
> suffering.  I don't know what it is, but there just seems to be a   
> very minimum priority given to GLIMS, or there's some technical   
> reason (the "exclusion zones" or whatever) that makes certain areas   
> very difficult to image.  There are lots of images of glaciers from   
> 2008-2009, but the majority are global map or other images that have  
>  saturated snow.  (Those work well for debris covered areas, so we   
> don't discount the fact that we have those.)  The Southern   
> Hemisphere GLIMS STAR has completed its summer season a couple   
> months ago, and the received images are fairly hit and miss   
> according to a random assessment of a few areas done in Tucson and   
> by some other GLIMS people; some really great images were received   
> in Jan-Feb-Mar 2009, but many areas have had no coverage this year   
> (or were attempted but were clouded out).  So I am fairly   
> apprehensive about this summer's northern hemisphere GLIMS STARs.
> Greenland was one big area where GLIMS was going really well, and of  
>  course that was a great thing.  I just wish something like the   
> Greenland coverage we had year after year (several received   
> low-cloud scenes of most parts of the coast each year) would happen   
> just once in the lifetime of GLIMS for nonpolar glaciers; or even   
> just one good image per season (with GLIMS gains) of most glaciers   
> would be a great improvement.  It just has not been achieved so far   
> in 9 years of ASTER.  I realize that we have acquired lots of GLIMS   
> scenes over the life of ASTER, so I am not issuing an all-out   
> complaint, but certainly there remain serious inadequacies.  I have   
> not done the analysis to see whether on average the Southern   
> Hemisphere did significantly better in 2009 than in other years   
> under the old STAR.  I just know that there are quite a few   
> significant glaciers that were not imaged, and some that were imaged  
>  had saturated snow (gains indicative of the global map program).
> Let me know whether you think the "one-fifth plan" will work   
> acceptably (plus an expected average of one summer image of the   
> other areas under the newly implemented STAR).  We will need to do   
> something similar for Antarctica next austral summer.
> --Jeff
>
>
>> Date: Wed, 20 May 2009 13:26:45 -0700
>> Subject: Re: US Mtg agenda
>> From: tulaczyk at pmc.ucsc.edu
>> To: Michael.J.Abrams at jpl.nasa.gov
>> CC: kargel at hwr.arizona.edu
>>
>> Jeff,
>>
>> Let's talk about this.  If at all possible, I would love to see more
>> coverage of Greenland/Antarctica without subtracting from your focus
>> on the smaller glacier systems.
>>
>> Cheers
>>
>> Slawek
>>
>> On 5/20/09, Michael Abrams <Michael.J.Abrams at jpl.nasa.gov> wrote:
>>> Slawek,
>>>
>>> Could you also discuss this with Jeff Kargel before the meeting (He is
>>> not attending). The GLIMS STAR was changed to reduce Greenaland
>>> coverage. Not sure about antarctica.
>>>
>>> Michael Abrams
>>> ASTER Science Team Leader
>>> Group Supervisor, Land Surface Processes
>>> NASA/Jet Propulsion Laboratory
>>> Mail Stop 183-501
>>> 4800 Oak Grove Dr.
>>> Pasadena, CA 91109
>>> 818-354-0937  FAX: 818-354-5148
>>> michael.j.abrams at jpl.nasa.gov
>>>
>>>
>>>
>>>
>>> Slawek Tulaczyk wrote:
>>>> Dear Mike,
>>>>
>>>> Could we reserve time for a discussion on increased data acquisition
>>>> over margins of Antarctica and Greenland?
>>>>
>>>> Cheers
>>>>
>>>> Slawek
>>>>
>>>> On Wed, May 20, 2009 at 10:29 AM, Michael Abrams
>>>> <Michael.J.Abrams at jpl.nasa.gov> wrote:
>>>>
>>>>> attached is US Team meeting agenda for monday morning. let me know of any
>>>>> changes/additions/etc.
>>>>>
>>>>> mike
>>>>>
>>>>> --
>>>>> Michael Abrams
>>>>> ASTER Science Team Leader
>>>>> Group Supervisor, Land Surface Processes
>>>>> NASA/Jet Propulsion Laboratory
>>>>> Mail Stop 183-501
>>>>> 4800 Oak Grove Dr.
>>>>> Pasadena, CA 91109
>>>>> 818-354-0937  FAX: 818-354-5148
>>>>> michael.j.abrams at jpl.nasa.gov
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>
>>
>> --
>> Professor Slawek Tulaczyk, Ph.D.
>> Department of Earth and Planetary Sciences
>> University of California, Santa Cruz, CA 95064, USA
>> phone: 831-459-5207, fax: 831-459-3074, tulaczyk at pmc.ucsc.edu
>
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-- 
  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)