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#2586 (Erroneous tidal constituent K1 in the AMM12 reference configuration) – NEMO

Opened 4 years ago

Closed 4 years ago

#2586 closed Defect (fixed)

Erroneous tidal constituent K1 in the AMM12 reference configuration

Reported by: smueller Owned by: smueller
Priority: low Milestone:
Component: MULTIPLE Version: trunk
Severity: minor Keywords: tides, BDY
Cc:

Description

Context

The K1 constituent in the tidal harmonic analysis of the sea-surface height field of the AMM12 reference model run changes substantially when toggling between the revised (default) and the legacy (nn_tide_var=0) tidal-constituent parameter set.

Analysis

In contrast to the legacy option, the revised parameter set includes negative equilibrium-tide amplitudes (see source:/NEMO/trunk/src/OCE/TDE/tide.h90@12377). In the case of the K1 constituent, such a negative amplitude is used; in comparison to the legacy parameter set, this is compensated by a phase shift of 180 degrees. While this sign change and phase shift cancel out in the computation of the astronomical tidal forcing at the ocean surface, only the phase shift affects the tidal forcing at open boundaries, which leads to the observed difference in the model results when switching between the default and legacy parameter-set option. Presumably, the same issue also affects the forcing of tidal constituents J1, L2, lam2, R2, and M3 at open boundaries, as well as the tidal-loading fields associated with constituents K1, J1, L2, lam2, R2, and M3 read in from external files when ln_read_load=.true..

Recommendation

Various adjustments could be made to rectify the AMM12 reference configuration, including the adjustment of the forcing dataset or a modification of the negative equilibrium-tide amplitudes to positive values with a compensatory phase shift.

Commit History (1)

ChangesetAuthorTimeChangeLog
14502smueller2021-02-18T19:48:54+01:00

Restoration of compatibility with existing tidal open-boundary forcing data sets through the adjustment of the sign convention used for equilibrium-tide amplitudes in the revised tidal-constituent parameter set (ticket #2586)

Change History (3)

comment:1 Changed 4 years ago by smueller

  • Owner changed from systeam to smueller
  • Status changed from new to assigned

comment:2 Changed 4 years ago by smueller

In 14502:

Error: Failed to load processor CommitTicketReference
No macro or processor named 'CommitTicketReference' found

comment:3 Changed 4 years ago by smueller

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

source:/NEMO/trunk@14502 has passed the standard SETTE tests; as expected, the AMM12 and WED025 SETTE runs differ from the corresponding runs performed using source:/NEMO/trunk@14476.

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