Ongoing work to reduce spurious numerical mixing. Mainly focused on testing the z~ scheme in the context of tidal models in the near future.
Work on z-tilde. Alex is working on creating a z~ version of GO8p8 on Monsoon and once he is convinced that is working, will commit that to a repository. The code is working and has been tested in several combinations of forcing etc, but I haven’t saved it to a repository yet. I need to find out how to do that!
Diagnose mixing in ORCA12 and compare with ORCA025 mixing. Alex will use his ACSIS runs on Archer2 to look at this, once it is running stably at 1/12°. I completed a satisfactory run of GO8p7 with z* on Archer2 last year, but I haven’t done mixing analysis yet (see next item).
Write NEMO code to calculate transports in density space at runtime. AM, MB Possible alternative strategy involving generating 5-day output at runtime and doing diagnostics using this, but I haven’t run on Archer2 since the recent shutdown.
Diagnose mixing in coupled models? Alex has done this for GO8p3 version of GC5. Have done this for C20 control GC5. Mixing is much lower than in CORE2-forced run, and similar to that with ERA5-forced simulation.
Once the first step is done, he will start work on adding z~ to a GC5 suite. Need to consider minor code changes for coupled configuration I have preliminary version of this, but need to eliminate rapid instability at high latitudes. Originally I thought this was linked to initial conditions in Arctic (which remains a significant issue), but it seems connected to the divergence calculation of the interface smoothing fluxes in sshwzv.F90.
Analysis of mixing in tidal runs: see SE-NEMO work plan. Paper on tidally forced GO8p0 is under review at Ocean Modelling. Need to discuss strategy for implementing tides in GOSI9 and GC5, building on results from SE-NEMO: I have a GC5 run with the same tidal setup as in my GO8p0 configuration (only 5 constituents, and no modification of bottom friction), but this isn’t optimum. My main goal is to be able to run GC5 with z~ and tides.
Try to diagnose mixing of AABW in Southern Ocean? I have started work on diagnosing density transformation rates from cabbeling and thermobaricity in the Southern Ocean, which in the past have complicated mixing analysis, in an ERA5-forced GOSI9.
Z-tilde blows up in ORCA12, John Thuburn (U. Exeter) is investigating.
Switch from Cox to Triad scheme DB. I still have doubts about whether this is working properly in my GOSI9 runs – I am in discussions with Diego.
Ongoing work to reduce spurious numerical mixing. Mainly focused on testing the z~ scheme in the context of tidal models in the near future.