Opened 6 years ago

Closed 6 years ago

Last modified 6 years ago

#1375 closed Defect (fixed)

degradation of North Atlantic solution in ORCA025 at 3.6

Reported by: davestorkey Owned by: nemo
Priority: normal Milestone:
Component: OCE Version: release-3.6
Severity: Keywords:
Cc:

Description

The solution in the North Atlantic seems to be significantly degraded at 3.6 compared to previous versions. From other tests I think this is due to the changes to the EEN momentum advection scheme in dynvor.F90. Attached pictures are 5-year means from a 10-year spinup forced with CORE2 atmospheric forcing. The SSH shows that at 3.6 the Gulfstream overshoots more at the separation point and then is too zonal at the "northward turning". This results in the return of the familiar cold bias in that region as seen in the SST plots.

Commit History (1)

ChangesetAuthorTimeChangeLog
5029davestorkey2015-01-14T17:32:37+01:00

Reinstate old formulation of EEN vorticity scheme as an option in NEMO 3.6. See ticket #1375

Attachments (4)

xhimo_aoeda_SSH_1981_1985.png (356.6 KB) - added by davestorkey 6 years ago.
5-year mean SSH from 10-year CORE2-forced ORCA025 run. Left: NEMO 3.4, right: NEMO 3.6 alpha
xjcmc_aodea_theta_SST_1981_1985.jpg (497.1 KB) - added by davestorkey 6 years ago.
5-year mean SST from 10-year CORE2-forced ORCA025. Bottom left: SST anomaly for NEMO 3.5, bottom right: SST anomaly for NEMO 3.6, top right: difference 3.6 minus 3.5
NEMO_3.5_1990_1999_SSHmSSHmean.gif (57.7 KB) - added by cbricaud 6 years ago.
NEMO_3.6_1990_1999_SSHmSSHmean.gif (58.4 KB) - added by cbricaud 6 years ago.

Download all attachments as: .zip

Change History (8)

Changed 6 years ago by davestorkey

5-year mean SSH from 10-year CORE2-forced ORCA025 run. Left: NEMO 3.4, right: NEMO 3.6 alpha

Changed 6 years ago by davestorkey

5-year mean SST from 10-year CORE2-forced ORCA025. Bottom left: SST anomaly for NEMO 3.5, bottom right: SST anomaly for NEMO 3.6, top right: difference 3.6 minus 3.5

Changed 6 years ago by cbricaud

Changed 6 years ago by cbricaud

comment:1 Changed 6 years ago by cbricaud

I have the same issue in my ORCA025 run.
see NEMO_3.6_1990_1999_SSHmSSHmean.gif and NEMO_3.5_1990_1999_SSHmSSHmean.gif.
Clément

comment:2 Changed 6 years ago by davestorkey

  • Resolution set to fixed
  • Status changed from new to closed

Gurvan views the change in the formulation of the EEN scheme as a numerical choice rather than a correction and recommended that we add the old version of the scheme as an option in NEMO 3.6 if we want to use it. I have now done this at revision 5029 of the trunk. The default option at 3.6 is still the new formulation.

The formulation of the vector invariant form of the momentum advection scheme in NEMO is the subject of ongoing investigation by Nicolas Ducousso, Mike Bell, Gurvan and others.

comment:3 Changed 6 years ago by jchanut

Changes must be duplicated in the time splitting routine.

comment:4 Changed 6 years ago by davestorkey

Thanks Jerome I forgot. I've put the changes to dynspg_ts.F90 in at 5032.

Note: See TracTickets for help on using tickets.