comments on initial research directions

[jkingslake]

Research Directions.md lays out the overarching ideas/questions driving this project quite well. Here are paragraph-level comments.

Paragraph 1: I would avoid making it sound like GIA is the only driver of grounding line (GL) readvance. Many other factors could cause it. Like changes in the supply of heat from the ocean, changes in snow accumulation, etc.

I dont think the reason readvance is important is that it reduces the contact area between the ocean and the ice. The front of the ice shelf could easily advance at the same rate or faster than the GL, so the total ice shelf area doesn't necessarily decrease. I think the main reason that readvance is important is that it increases the ice sheet's area and volume above flotation - the latter decreases eustatic sea level. But you can look at ice shelf extent during these simulations and think about how it affects the ice sheet. On the one hand, yes larger ice shelves increase the interaction with ocean, but also larger ice shelves increase the buttressing force exerted on the ice sheet, particularly if the ice shelf is confined in an embayment. Because of this dependence on the location of the ice shelf it could be interesting to look at how this changes at different stages of the glacial cycles simulated in the simulations.

Paragraph 2: yes, these are some of the effects that we discussed very briefly in the methods section of the 2018 paper. And I think your project can dig into these idea deeper using the PISM simulations . For example, by plotting out GIA rates, GL positions, ice sheet volumes, at the different stages of the simulations and in different sectors of the ice sheet. Also not just time series, but maps of the changes (and I know you have a made a good start on this here).

Paragraph 3: The effect you are talking about here was discussed even less that the viscosity signal. This is definitely something that you can explore further with the simulations. E.g., plot out profiles of ice surface and bed height along flow lines for different times in the simulations and for different simulations. These will all be nice exercises in slicing, interpolating, and plotting in xarray.

Paragraph 4: It is worth talking to the Lamont GIA group when you meet them about whether this is likely to be a large signal. Also think about how sea level directly affects GL position (i.e., not via GIA, but directly, by determining where the ice becomes afloat), and whether this contributes to, counteracts, dominates, or is negligible compared to, this GIA-effect you mention in this paragraph.

Paragraph 5: Let's talk about this other effects that you elude to sometime.

Hope this helps!

[ct3012]

Thank you very much for your detailed and valuable comments. I made some edits on my research directions. b694cb5649563c3f748021a34999cec2956b37a6 93530264be15eb5400fcb0b026d42a112b8fee27 a5a6ac117215d5e7c42c318c9047cf5b4a3fc8eb Could you please check these when you have time? Thank you very much for your help.

[jkingslake]

Good work! I think the introduction is improved, but can probably do with a bit more back and forth.

The main ideas look good about what to do with the model output. Don't forget to look at maps of the spatial distribution of variables too. (that might have been in there and I just missed it).

Good work!

[ct3012]

Dear Professor Kingslake, Thank you very much for checking my work. I will work a little bit more on the introduction for my next draft of the thesis proposal. I will also keep in mind about the spatial distribution of the variables as I do further analyses. I appreciate all your advice!