Last edition: 06/02/20 16:47:50 by agn

The PI is responsible to closely follow the progress of the action, and especially to contact NEMO project manager if the delay on preview (or review) are longer than the 2 weeks expected.

  1. Summary
  2. Preview
  3. Tests
  4. Review


Action PHYPRO-01_agn_OSMOSIS_science
PI(S) George Nurser
Digest Improvements to OSMOSIS OBL to improve behaviour in shelf-sea areas and under sea ice
Dependencies If any
Branch source:/NEMO/branches/{YEAR}/dev_r{REV}_{ACTION_NAME}
Previewer(s) Names
Reviewer(s) Names
Ticket #2352


Improve OSMOSIS ocean boundary layer (OBL) model in 3 areas:

  1. Ensure consistent behaviour of OSMOSIS-OBL under ice. Revert to classic shear turbulence based on ice-ocean turbulent friction velocity where ice areal coverage is high; scale with ice fraction between shear turbulence and Langmuir turbulence model. Where Stokes drift unavailable, move to parametrised form.
  1. Improve representation of OSMOSIS-OBL mixing in equatorial regions. Include mixing associated with shear of mean flow as in equatorial undercurrent.
  1. Mixing in shelf seas. The OSMOSIS-OBL is primarily a surface boundary layer model and so is not set up for bottom-driven tidal mixing. We intend to transition to GLS in shelf seas.

􏱔􏱦􏱋􏱌􏱧􏱎 􏱺􏱢􏱟􏱺􏱢􏱞􏱢 􏱪􏱏􏱱􏱎􏱔􏱎 􏱓􏱜􏱩􏱎􏱋 􏱪􏱎􏱬􏱷􏱣􏱏􏱎􏲀 􏱣􏱜 􏱐􏱱􏱎 􏱐􏱋􏱌􏱦􏱣􏱏􏱪 􏱴􏱪􏱱􏱎􏱬􏱋 􏱾􏱣􏱐􏱱 􏱎􏲄􏱓􏱬􏱐􏱌􏱋􏱣􏱬􏱤 􏱓􏱜􏱩􏱎􏱋􏱏􏱓􏱋􏱋􏱎􏱜􏱐􏱵 􏱬􏱜􏱩 􏱣􏱜 􏱪􏱱􏱬􏱤􏱤􏱌􏱾 􏱪􏱱􏱎􏱤􏱫 􏱪􏱎􏱬􏱪 􏱴􏱣􏱜􏱐􏱎􏱋􏱬􏱏􏱐􏱣􏱌􏱜 􏱾􏱣􏱐􏱱 􏱕􏱌􏱐􏱐􏱌􏱔 􏱕􏱌􏱓􏱜􏱩􏱬􏱋􏱝 􏱤􏱬􏱝􏱎􏱋􏱵􏲂 􏱰􏱎􏱧􏱎􏱤􏱌􏱦 􏱩􏱣􏱬􏱨􏱜􏱌􏱪􏱐􏱣􏱏􏱪 􏱎􏱜􏱎􏱋􏱨􏱝 􏱕􏱓􏱩􏱨􏱎􏱐 􏱐􏱌 􏱬􏱪􏱪􏱓􏱋􏱎 􏱎􏱜􏱎􏱋􏱨􏱎􏱐􏱣􏱏 􏱏􏱌􏱜􏱪􏱣􏱪􏱐􏱎􏱜􏱏􏱝􏲂􏱞􏱔􏱦􏱋􏱌􏱧􏱎 􏱺􏱢􏱟􏱺􏱢􏱞􏱢 􏱪􏱏􏱱􏱎􏱔􏱎 􏱓􏱜􏱩􏱎􏱋 􏱪􏱎􏱬􏱷􏱣􏱏􏱎􏲀 􏱣􏱜 􏱐􏱱􏱎 􏱐􏱋􏱌􏱦􏱣􏱏􏱪 􏱴􏱪􏱱􏱎􏱬􏱋 􏱾􏱣􏱐􏱱 􏱎􏲄􏱓􏱬􏱐􏱌􏱋􏱣􏱬􏱤 􏱓􏱜􏱩􏱎􏱋􏱏􏱓􏱋􏱋􏱎􏱜􏱐􏱵 􏱬􏱜􏱩 􏱣􏱜 􏱪􏱱􏱬􏱤􏱤􏱌􏱾 􏱪􏱱􏱎􏱤􏱫 􏱪􏱎􏱬􏱪 􏱴􏱣􏱜􏱐􏱎􏱋􏱬􏱏􏱐􏱣􏱌􏱜 􏱾􏱣􏱐􏱱 􏱕􏱌􏱐􏱐􏱌􏱔 􏱕􏱌􏱓􏱜􏱩􏱬􏱋􏱝 􏱤􏱬􏱝􏱎􏱋􏱵􏲂 􏱰􏱎􏱧􏱎􏱤􏱌􏱦 􏱩􏱣􏱬􏱨􏱜􏱌􏱪􏱐􏱣􏱏􏱪 􏱎􏱜􏱎􏱋􏱨􏱝 􏱕􏱓􏱩􏱨􏱎􏱐 􏱐􏱌 􏱬􏱪􏱪􏱓􏱋􏱎 􏱎􏱜􏱎􏱋􏱨􏱎􏱐􏱣􏱏 􏱏􏱌􏱜􏱪􏱣􏱪􏱐


The development branch for 2019-WP action VALID-02_GeorgeN-evalOSMOSIS has recently been synchronized with source:/NEMO/trunk@12925 (changesets [12928] and [12934])and will form the basis for the source-code "streamlining" activities of action 2020WP/ENHANCE-14_smueller_OSMOSIS_streamlining. A new branch with the new physics will be spun-off this streamlined branch 2020WP/ENHANCE-14_smueller_OSMOSIS_streamlining.

Changes for (1) and (2) will be mostly restricted to the routine zdfosm.F90. There will be a new subroutine added to handle the shear-induced mixing.

The transitioning to GLS will require setting up of the GLS routine zdfgls.F90 and code to link it with the master routine zdfosm in zdfosm.F90

Documentation updates

An extra paragraph or two will be added to the documentation in section 9.1.5 of the manual.


Since the preview step must be completed before the PI starts the coding, the previewer(s) answers are expected to be completed within the two weeks after the PI has sent the request to the previewer(s).
Then an iterative process should take place between PI and previewer(s) in order to find a consensus

Possible bottlenecks:

  • the methodology
  • the flowchart and list of routines to be changed
  • the new list of variables wrt coding rules
  • the summary of updates in literature

Once an agreement has been reached, preview is ended and the PI can start the development into his branch.



Aim: to test that OSMOSIS_OBL behaves correctly under ice for a range of ice fractions
Configuration: 2D model SI3 + OCE, with domain_cfg, idealised forcing (cooling/freezing phase + warming/melting phase , initial state with gradation in ice cover.

Output diagnosed mixed-layer depth after specified time of cooling/mixing. Check against control run values.

Defined but not developed.


Aim: to test that OSMOSIS_OBL gives a reasonable diurnal cycle of near-equatorial mixing
Configuration: 2D model with ideal-age tracer TOP + OCE along meridional section across the equator 5°S—5°N with initial state with westerly surface zonal flow and easterly zonal undercurrent, zero ideal-age tracer throughout.
Idealised diurnal cycle of surface forcing.

Output mixed-layer depth + vertical profile of age tracer after specified time of cooling/mixing. Check against control run values.

Defined but not developed.


Aim: to test that OSMOSIS_OBL gives a smooth transition between open ocean and shelf conditioins
Configuration uncertain. Might again use 2D model with gradient in tidal flow and/or bottom depth Output and check profile of diagnosed mixed-layer depth against control run values.

Loosely defined and not developed.


A successful review is needed to schedule the merge of this development into the future NEMO release during next Merge Party (usually in November).


  • Is the proposed methodology now implemented?
  • Are the code changes in agreement with the flowchart defined at preview step?
  • Are the code changes in agreement with list of routines and variables as proposed at preview step?
    If, not, are the discrepancies acceptable?
  • Is the in-line documentation accurate and sufficient?
  • Do the code changes comply with NEMO coding standards?
  • Is the development documented with sufficient details for others to understand the impact of the change?
  • Is the project literature (manual, guide, web, …) now updated or completed following the proposed summary in preview section?


Is the review fully successful? If not, please indicate what is still missing

Once review is successful, the development must be scheduled for merge during next Merge Party Meeting.

Last modified 2 months ago Last modified on 2020-06-02T16:47:50+02:00