[MITgcm-support] Spurious behaviour beneath ice shelves with advection scheme 33

[Claire Yung]

Hi MITgcm users,

Apologies if this issue has already been noted. In idealised MITgcm ice shelf cavity model tests we’ve found some strange looking temperature-salinity space profiles that suggest anomalously fresh water (not following the expected ice shelf water mass transformation), mostly occurring in the grid cells immediately below ice. This problem occurred with the 3rd order DST flux limited advection scheme 33:
staggerTimeStep=.TRUE.,
 tempAdvScheme=33,
 saltAdvScheme=33,
The issue was resolved by using the 2nd order flux limiter advection scheme 77 instead (thanks Paul Holland for the suggestion and Tore Hattermann for uncovering the problem). Just wanted to flag this issue for other/future MITgcm ice shelf users! Though, if anyone has looked into why this happens I’d be keen to hear.

Thanks
Claire

~~~
Claire Yung [she/her]
PhD student
Research School of Earth Sciences
The Australian National University
Canberra ACT 2600
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