GOSI10: minor changes package

[ukmo-cguiavarch]

Issue to reference all the smaller changes that we plan to implement in GOSI10.

1. Internal wave mixing: implementing the De Lavergne scheme instead of Simmons
2. Wind stress: implementing the current feedback option (Renault et al) instead of the relative wind stress
3. Chlorophyll: using a 2D map climatology instead of constant value ( see https://code.metoffice.gov.uk/trac/gmed/ticket/631 )
4. Remove partial slip from SO package as it is not required with the new bathymetry.
5. Add key_qco (only option at NEMO5) and qco like vvl interp (see #2)

1 and 2 need to be implemented before we upgrade to NEMO5 as it will allow to simplify the GOSI branch as Simmons et al and the relative wind stress are not available in the trunk at NEMO 4.2 and above.

[oceandie]

Should we include the inclusion of key_qco here? ... according to these notes:

_We should test the QCO vertical coordinate (keyqco) at v4.2.2 before porting to NEMO 5, as VVL will no longer be available

[ukmo-cguiavarch]

Internal waves mixing De Lavergne et al (2020):

Adam has interpolated the De Lavergne et al (2020) input files for eORCA025 (@4.2) .

The file is available on monsoon: /projects/jmmp/atblak/ancil/eORCA025/zdfiwm_forcing_eORCA025.nc

namelist settings are: &namzdf_iwm ln_mevar = .true., ! variable (T) or constant (F) mixing efficiency ln_tsdiff = .true., ! account for differential T/S mixing (T) or not (F)

cn_dir = './INPUT/' ! root directory for the iwm data location ! ! file name ! frequency (hours) ! variable ! time interp.! clim ! 'yearly'/ ! weights filename ! rotation ! land/sea mask ! ! ! ! (if <0 months) ! name ! (logical) ! (T/F) ! 'monthly' ! ! pairing ! filename ! sn_mpb = 'zdfiwm_forcing_eORCA025.nc' , -12. , 'power_bot' , .false. , .true. , 'yearly' , '' , '' , '' sn_mpc = 'zdfiwm_forcing_eORCA025.nc' , -12. , 'power_cri' , .false. , .true. , 'yearly' , '' , '' , '' sn_mpn = 'zdfiwm_forcing_eORCA025.nc' , -12. , 'power_nsq' , .false. , .true. , 'yearly' , '' , '' , '' sn_mps = 'zdfiwm_forcing_eORCA025.nc' , -12. , 'power_sho' , .false. , .true. , 'yearly' , '' , '' , '' sn_dsb = 'zdfiwm_forcing_eORCA025.nc' , -12. , 'scale_bot' , .false. , .true. , 'yearly' , '' , '' , '' sn_dsc = 'zdfiwm_forcing_eORCA025.nc' , -12. , 'scale_cri' , .false. , .true. , 'yearly' , '' , '' , '' /

[atb299]

The zdfiwm input file is now available at all 3 resolutions here: /projects/jmmp/atblak/ancil/eORCAxx

I also copied across the original file that I interpolated and the weights for the eORCA025 and eORCA12 grids.

[ukmo-cguiavarch]

GOSI10p2.0(u-dh157) includes the following changes compared to GOSI10p1.2:

1. Internal wave mixing: implementing the De Lavergne scheme instead of Simmons
2. Wind stress: implementing the current feedback option (Renault et al) for the relative wind stress instead of traditional relative wind stress calculation (not available from NEMO4.2)
3. Chlorophyll: using a 2D map climatology instead of constant value ( see https://code.metoffice.gov.uk/trac/gmed/ticket/631 )
4. Remove partial slip from SO package as it is not required with the new bathymetry.
5. Add key_qco

The changes in GOSI10p2.0 compared to GOSI10p1.2 are:

• VALSO: reduction of ACC transport associated with increased Weddell gyre transport

• VALNA: significant change in SSS (fresher) and MLD(shallower) in Labrador sea

• VALTRANS: reduction of transport in Denmark Strait and Faroe Bank channel, increase in Lombok strait

• marine_assess u-157 vs. udg878: large changes in salinity in Arctic (fresher in the surface layers , saltier in subsurface up to 300m)

• seaice_assess u-157 vs. udg878: no significant changes

To understand the changes 3 sensitivity experiments have been carried to test changes individually: a. revert to relative wind stress (marine_assess u-di436 vs. u-dh157) b. reintroduce partial slip in Southern Ocean (marine_assess u-di437 vs. u-dh157) c. reverting to Simmons et al instead of De Lavergne (marine_assess u-di438 vs. u-dh157)

From these experiment we can conclude that :

• the reduction in ACC transport is linked to the removal of the partial slip in the Southern Ocean (see VALSO below). At this point I suggest to not reintroduce the partial slip in the SO as more changes will be introduced in future prototypes likely to have an impact on ACC. We can revisit at a later time.

• the large changes in Salinity at high latitudes in the Northern Hemisphere (Lab Sea + Arctic) are linked to the change of scheme for internal wave mixing from Simmons et al to De Lavergne. Impact of Simmons et al on salinity at the surface, at 100m.

• The changes in transport (see VALTRANS below) are also linked to the internal wave mixing scheme.

• current feedback (Renault et al) has a limited impact on large scale properties (T/S) but I have not looked at the impact on EKE. Note that we don't have the information on the ocean currents seen by JRA so we are not fully using the the current feedback correction.

VALSO:

VALNA:

VALTRANS: