Technical Working Group Meeting, October 2016


Date: 11th October 2016

  • Marshall Ward (NCI, Chair)
  • Aidan Heerdegen (ARCCSS)
  • Nick Hannah (ARCCSS/Breakaway Labs)
  • Justin Freeman and Mirko Velic (BoM)
  • Russ Fiedler and Matt Chamberlain (CSIRO Hobart)
  • Peter Dobrohotoff (CSIRO Aspendale)

Code submissions

  • Mirko submitted major refactoring update to the nudging code for MOM. Three different options depending on namelist. One just sponge, one does nudging, another does adaptive nudging. Added instantaneous update from datafile. Wanted to reproduce the MOM4 behaviour. Tested, and now works. Was broken previously.
  • Can merge, but we need some testing on other coverage. Currently have a dozen test cases. Not sure any touch this, but will run them anyway. Justin suggests they provide a test case which covers some of these sections.
  • Nic asked that if possible functional and formatting changes be separate commits, as it makes approving pull requests much easier
  • Maybe not merge yet, but get testing working to cover this. Justin will look at adapting an existing MOM test case for this purpose.

Exchange grids and smoothing

  • Justin was talking to Paul Sandery about exchange grids. An issue with tiling as a result of remapping. Was asking about how Russ implemented smoothing.
  • If you took interim fields end up with horrible pattern with convergence of winds with 1st or 2nd order remapping due to discontinuity. Russ wrote some code that does 2D smoothing within the surface boundary condition. Bypasses the exchange grid and used the flux exchange to native grids options(?). GFDL apply an interpolation when they read in via data override. So can use the data override to interpolate to the finer grid and can control this.
  • This is only a problem with conservative remapping with exchange grids.
  • Nic didn’t think this was a problem with standard MOM-SIS runs, but Russ said it should still be visible in the fluxes with coarse (1deg) forcing fields.
  • With ACCESS high res ocean the fields and fluxes are extremely blocky, so Nic smooths on the ice grid, before it comes into the ocean grid, on a tile by tile basis.
  • If you want local conservation, cannot get around this. In ACCESS can use linear interpolation and then post-process to get global conservation. Doesn’t work with local conservation.
  • Marshall suggested we have some test cases that don’t run the model but test coupling and fields
  • These effects most often seen when there is a big difference in resolution between model fields and input fields. Look at wind stress fields. Maybe some of the barotropic fields, height and definitely convergence in barotropic restart file.
  • Paul’s runs do not use conservative remapping. Don’t see the horrible features with some of the other schemes.
  • Nic: do we need a central document discussing this?

OceanMaps 4

  • Justin is trying to prototype OceanMaps 4. Picking up on Paul Sandery’s work. He has been using MOM5-SIS and using bulk fluxes to link the models. Would like to standardise, or make these things available. Not sure how it connects to linkage project.
  • Nic felt it was good to know what Paul does. So far no code changes?.


  • Aidan got a query from Dave Hutchinson, asking if latest version of FMS was included in the code on MOM5 repo. Marshall has updated FMS in the master branch to Ulm, but not to Verona, the latest version.
  • Move FMS to a submodule of MOM5 rather than manually included inline
  • Goal is for Rui Yang (NCI) to work on parallel netCDF in MOM5

Model release naming and definition

  • Still an issue
  • Nic has put an access-om model on OceansAus. Has version controlled input files and code. Can be downloaded, compiled and run.


  • ACCESS-OM models are using CICE4.?, but Peter is using 5.1.
  • There are many bug fixes and performance improvements in the version of CICE Nic has been working on that would be beneficial to Peter.
  • Peter is working on a refactoring of CICE5.1
  • We should align our work to the same version of CICE.
  • First step is for Peter’s version of CICE5.1 to be hosted on OceansAus and development work to be based from that so we can work together. Some discussion about the best way to do this.


  • Just and Mirko work up test cases to cover the nudging code and give them to Nic.
  • Nic to add new test cases to Jenkins test suite.
  • Aidan to add and to uptime monitoring service (Uptime Robot).
  • Add Peter’s CICE5.1 config to OceansAus github repo
  • Nic create a discussion document (on COSIMA?) to document current approaches and strategies for future
  • Marshall to move FMS to submodule of MOM5 github repo. Liase with Nic on implementation?
  • Others test Nic’s access-om model config on OceansAus