Opened 5 years ago

Closed 5 years ago

Last modified 3 years ago

#1482 closed Bug (fixed)

No explicit lateral tracer diffusion in NEMOTAM

Reported by: sam Owned by: nemo
Priority: high Milestone:
Component: TAM Version: release-3.4
Severity: Keywords: TAM
Cc:

Description

When Laplacian isopycnal tracer diffusion (the default option for ORCA2) is selected, the addition of non-zero horizontal background diffusion (parameter 'ln_ahtb_0') causes the test 'tra_ldf_iso_ad' of the corresponding tangent-linear and adjoint subroutines to fail. Without additional background diffusion the test of this option for lateral diffusion passes.

Analysis of the corresponding code revealed that the lateral diffusion coefficients are scaled by the value of variable 'rldf' (in OPA_SRC/LDF/ldftra_substitute.h90) which remains undefined in NEMOTAM (for the non-linear model the value of 'rldf' is set to 1.0). Setting 'rldf' to 1.0 at the start of each of the subroutines 'tra_ldf_tan', 'tra_ldf_adj', and 'tra_ldf_adj_tst' in module 'traldf_tam' would provide the expected values of the diffusion coefficients.

The assignment of 'rldf' with a value of 1.0 results in a failure of the test of the OPATAM subroutines for some of the options for lateral diffusion (the tests of the code in modules 'tra_lap_tam' and 'tra_iso_tam' fails, the test of the code in module 'tra_bilap_tam' completes successfully). If without definition of 'rld' the lateral diffusion coefficients are set to zero, the test of the tangent-linear and adjoint code for lateral diffusion becomes ineffective, which seems to explain why the subroutine tests for the tangent-linear and adjoint code previously did not reveal any problem with the 'tra_lap_tam' and 'tra_iso_tam' code.

Commit History (1)

ChangesetAuthorTimeChangeLog
5151pabouttier2015-03-18T11:47:26+01:00

Fixing defects in traldf_tam routines; See Ticket #1482 an #1483

Change History (5)

comment:1 Changed 5 years ago by bouttier

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

comment:2 Changed 4 years ago by nicolasmartin

  • Keywords TAM added

comment:3 Changed 4 years ago by nicolasmartin

  • Keywords nemo_v3_4* added

comment:4 Changed 3 years ago by nemo

  • Keywords release-3.4* added; nemo_v3_4* removed

comment:5 Changed 3 years ago by nemo

  • Keywords release-3.4* removed
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