Opened 2 weeks ago

Last modified 2 weeks ago

#2144 new help

Sea ice edge error in UM with custom ancillaries

Reported by: dsergeev Owned by: um_support
Priority: normal Component: UM Model
Keywords: ancils, ostia, sst, sea ice Cc:
Platform: Monsoon2 UM Version: 10.2

Description

I'm trying to run the nested UM with "custom" SST and sea ice cover ancillary files created using xancil from the OSTIA dataset.

To let the model use my ancillary files, I added these lines to app/um/rose-app.conf:

[namelist:items(5997b35c)]
ancilfilename='$UM_ANCIL_MASK_DIR/qrclim.sst'
domain=1
!!interval=1
!!period=1
source=2
stash_req=24
update_anc=.false.
!!user_prog_ancil_stash_req=
!!user_prog_rconst=0.0

[namelist:items(9500b563)]
ancilfilename='$UM_ANCIL_MASK_DIR/qrclim.seaice'
domain=1
!!interval=1
!!period=1
source=2
stash_req=31
update_anc=.false.
!!user_prog_ancil_stash_req=
!!user_prog_rconst=0.0

The model runs successfully. However, something goes wrong at the edge of sea ice cover, producing erroneous results, e.g. in sensible heat flux (see the figure attached).

What could be causing the problem?

Cheers,
Denis

Attachments (1)

sea_ice_edge_issue.png (1.5 MB) - added by dsergeev 2 weeks ago.
sea ice edge issue

Download all attachments as: .zip

Change History (3)

Changed 2 weeks ago by dsergeev

sea ice edge issue

comment:1 Changed 2 weeks ago by willie

Hi Denis,

This could be due to the sea ice and sst ancillaries being based on an inaccurate land/sea mask. You need to make sure that the ancillaries are all based on the same land/sea mask.

Regards
Willie

comment:2 Changed 2 weeks ago by dsergeev

Hi Willie,

Thanks for your reply.

I indeed had an issue with land mask in OSTIA not matching the UM mask, causing the model to crash, but I think I fixed it by "remasking" sea-ice and SST ancillaries with the UM mask.

Besides, there is no land that can be mismatched over the open water (in other words, sea area covered with ice is still sea, not land). Or am I missing something here?

Denis

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