proposed extra fields for WGMS glacier classifications in GLIMS database

[Bruce Raup]

Hi All,

Thanks for the responses on the additional database fields.  We could add
the following fields to the Glacier_Dynamic table (exact names to be
determined):

primary_classification2
frontal_characteristics2
tongue_activity2
  (same valids as corresponding primary fields)

debris_cover
  nil, low, moderate, heavy, thin
debris_distribution
  medial moraines, patchy, terminus cover


I like Jeff's proposed valids for the "debris" fields.  I thought at first
that a simple numerical value indicating percent of debris cover might be
better, but upon reflection, it seems that a few simple categories will be
easier to search on, and are appropriately qualitative.  If someone wants
quantitative debris data, they could, in theory, go to the debris
"segments", if they're there, and calculate the percent cover.

--Bruce


On 2003-02-27 08:49 -0700,  Jeffrey S Kargel wrote:

> >1.  Is it sufficient to add extra fields for just the three listed above?
>
> I see that there is no place, other than in a comment, to indicate
> something about debris cover.  Possibly in "longitudinal characteristics"
> there could be an entry for "debris cover abundance," with possible valids
> being nil (estimated <1% ice-free pixels below snowline, low (estimated
> ice-free cover 1-10% of pixels below snowline), moderate (10-50% ice-free
> pixels below snow line), heavy (50-100% ice-free pixels below snowline),
> and thin (debris cover may be widespread but few pixels are ice-free below
> the snowline-- there is dominantly subpixel mixing of debris and ice).
> There could also be an indication of the qualitative "distribution of
> debris," with up to 2 valids, including: medial moraines, patchy (as from
> landslides for example, i.e., lacking medial moraine type structure),
> terminus cover.
>
> >2.  Is it sufficient to add only one extra field to each (so that a given
> >glacier could have two "primary_classification"s at one point in time)?
>
> For simplicity, I think 2 is enough.  There will be instances where people
> really want more than 2, but I think those will be few.
>
> I am replying to the whole list, since my suggestion under #1 may require
> some broad discussion. I also think that before the final stamp of approval
> is placed on the revised database structure and valids definition (but
> after the DB WG has had their say in this new round of revision), perhaps
> it should be opened to comment from the entire GLIMS group.  Judging from
> the small response to some related emailings and solicitations of data,
> there may need to be another hand-holding e-tutorial on how to access the
> database structure and definitions, and how to input data, plus a pretty
> stern resolicitation of data for the database.  People have simply got to
> get into the database.  There may need to be a individualized
> communications with some RCs, and I would be happy to do my part in that if
> needed.
>
> --Jeff K


On 2003-03-03 13:31 -0700,  Luke Copland wrote:

> Hi Bruce,
>
> I agree with your proposal to allow more than one value for the
> following fields:
>
> > primary_classification
> > frontal_characteristics
> > tongue_activity
>
> ...as we discussed at Chamonix, it's often impossible to place a glacier
> into only one classification. Saying this, we should only need to have
> two valids for each field to cover most eventualities.
>
> One other field that you might think about allowing two classifications
> for is the 'Tongue_act' - this is so that surge glaciers can be properly
> described. This is to allow for the fact that (e.g.) we might know that
> a glacier is surge-type (i.e., category 7), but when it's not in its
> active phase the terminus might be retreating or advancing (i.e., any of
> categories 1 to 5).
>
> It would be of major help when putting together the database to have a
> detailed description (and example imagery) of the permitted valids for
> each of the classifications. Fabian Munz showed an example of this in
> Chamonix, so I was wondering if you've had any chance to follow up on
> it. I've put together my own description of valids (see attached) based
> largely on the following book (although this doesn't cover any of the
> proposed new categories for debris cover, etc.):
>
> Armstrong, T., Roberts, B. and Swithinbank, C. 1973. Illustrated
> Glossary of Snow and Ice. Cambridge, Scott Polar Research Institute
> Special Publication No. 4.
>
> And finally, I like Jeff's suggestion of adding a descriptor for debris
> cover. The valids he suggests seems reasonable, and it would be useful
> to be able to include this information in the database.
>
> Cheers,
> Luke.
>
> P.S. Feel free to copy this email to the general GLIMS distribution list
> as you see fit.
>
>

-- 
Bruce Raup                                               Phone:  303-492-8814
National Snow and Ice Data Center, U. of Colorado, 449 UCB, Boulder, CO 80309