search

OGGM / oggm

Open Global Glacier Model
http://oggm.org
BSD 3-Clause "New" or "Revised" License
218 stars 105 forks source link

Ideas to convert flowlines back to 2D areas / geometries #1192

Open fmaussion opened 3 years ago

fmaussion commented 3 years ago

This question comes back often: at the moment, there is no way to convert the flowlines back to some 2D region on a map, because 1D glaciers are a simplification of the true geometry.

Here are two ideas about how we could implement something in OGGM. Both ideas would be relatively easy to implement, it just needs someone to do it ;-)

1. Via the width geometry

This would work only with geometrical centerlines. One could use the information about the location of the centerlines and their width at any point in time to reconstruct a shape of the glacier:

a1

This won't be perfect of course, but would work for both advancing and retreating glaciers

2. via the glacier bins

This would work only for retreating glaciers, but it would work for both the geometrical and elevation bands flowlines. Since we know the location of each 2D grid point that contributed to a 1D bin, we could make the step "backwards" and mark the location on the map that have melted:

a2

or even we could "redistribute glacier mass" somehow for more realistic volume change.

Other ideas or contributions welcome!

fmaussion commented 2 years ago

Now that I think of it, I wonder how an adaptation of this task here: https://github.com/OGGM/oggm/blob/9cc743ad581577f1b87a45fb2aec4d76ae73ec5d/oggm/core/inversion.py#L747 to accept model geometry files each year and "re distributing thickess" on an already known bed would work. It seems maybe the most straightforward way to have time-evolution of 2d maps... Something to think about

fmaussion commented 2 years ago

This would be closer to option 2