Grounding line retreat

[mankoff]

sankey/dat/aq_baseline.csv

Line 10 in 8476eb7

GZRET,Grounding line retreat,100,TODO

Need estimate of GZ retreat in Antarctica

[chadagreene]

I think accurate numbers of grounded-ice mass change resulting from GL retreat are gonna be hard. I don't know of any continuous, time-evolving GL product. Stitching together segments of landward limits of flexure seems pretty labor intensive, and there are lots of areas of missing InSAR data or different interpretations of landward limits of flexure depending on things like what part of the tidal cycle was sampled, etc.

The easiest approach I can think of is to use a hydrostatic assumption and calculate changes in the floating ice volume resulting from dh/dt. (Konrad et al. 2018 took a similar approach) Doing this would be relatively straightforward, but getting DEMs to line up with dh/dt might involve a bit of missing data around the edges of the ice sheet. And many of the dh/dt products apply an a-priori assumption about where the grounding line is for processing, so I'm not sure what that means for trying to apply gridded dh/dt for estimates of GL migration.

Is there any other approach you're thinking of?

[mankoff]

I didn't have a 'grounding line retreat' issue for Greenland because I was neglecting it, but since you raise the issue we should address it.

The easiest way might be to get a few sentences from Millan, or text from https://doi.org/10.1038/s41467-023-42198-2 . For example, they report

Retreat of the Petermann’s GL was reported to be 7 km between 1992 and 2021,

So if we have an estimate of thickness and width near the GZ, we can get a rough estimate of average annual mass flow due to retreat. Uncertainty may be large, and overall this is a small term in Greenland.