Plans for BLOM/iHAMOCC for NorESM2.5

[TomasTorsvik]

Tentative plans for default (and optional) settings for BLOM/iHAMOCC towards NorESM2.5

• We will keep the MCT support until the technical release of NorESM2.5

• cgs units support will phase out - likely keep unit support for the restart files reading to enable restart from former restart files

BLOM-specific

• only mks (default) (remove cgs dependencies)
• Add 2 degree grid resolution
• Test all model configurations with NUOPC coupler
• Apply existing higher order vertical reconstruction for the remapping of diagnostic fields on to reference depths (hybrid coord. only, reconstruction does not exist for isopycnic coord.)

iHAMOCC-specific

• Reconsider output for Hamocc kwrbioz off - enable remin and primary prod throughout full water column #367 & to make it default (+ remove the old split) - see Removing process separation between euphotic and deep ocean regions in iHAMOCC? #399
• Cold start of preformed (silicate) tracer - handle all preformed tracers equally - refer to Initialization of preformed tracers #356 for the provision of climatologies of preformed tracers. Clean-up of restart option for preformed silicate (currently checks, if prefsilicate is present, which could be removed)
• Remove/modify compsets for the extended N cycle (in cime_config/config_component.xml)
• Potentially enable to include weathering rates
• Nitrogen cycling interactive coupling through NUOPC?
• New DOC code (first) as optional
• Write output for rivers and any interpolated input fields introduced by Mariana
• Write output for limiting nutrient

Planning for release-1.7

Tasks under this heading can go into a new release-1.7, and will be carried forward into NorESM2.5.

BLOM-specific

• BLOM code refactorization
• hybrid coordinates (default) (isopycnal optional)
• Add 1/2 degree grid resolution

iHAMOCC-specific

• (potentially) making output files more cdo-compatible Add lon,lat info in iHAMOCC output to more comply to cdo commands  #355
• Potentially remove separation of processes into euphotic and non-euphotic zone processes - refer to Enable primary production beyond current kwrbioz and enable POC remin above #365 and Hamocc kwrbioz off - enable remin and primary prod throughout full water column #367
• Make preformed tracers optional - to enable switching them off for HR runs - done via Making preformed tracers optional to enable HR runs without them #394
• Remove the option to run cyanobacteria (bluefix) in the MLD (default remains to run them in the euphotic zone) - see Remove MLD switch for cyanobacteria - making euphotic zone N2 uptake remaining default  #395 and Remain with cyanobacteria only in euphotic zone. #396
• bugfix sediment extended N-cycle Bugfix DNRA and introduce max_limiter #413
• dust flux to sediment output Dust fluxes output and add descriptions in the xml-namelist file #420
• Unify N-deposition reading - done with always obtain ndep from datm or cam using cmeps/cdeps #410 (for nuopc) - see Preparing N-deposition input files for CMIP6 scenarios and historical runs #397 and Unify N-deposition input reading #398 for some further discussion. For post- BLOM tag v1.6.x simulations, nuopc is expected to handle the input, while for tag v1.6.x simulations with the extended nitrogen cycle switched on, a limited set of input files are generated by @jmaerz (request in case of interest)
• Make i) T-dep. and ii) O2-dep. of remineralization available to default model code via thus far optional switch- see Step-wise introduction of T-dep. and O2-dep of remineralization? #400 and Introduce switch dor T- and O2-dependent remineralization #424 , where the first step with a switch is taken for the water column - sediment thus far missing (only realized for the extended N cycle)

[TomasTorsvik]

This should maybe go into the milestone description at some point. Just edit the first entry if you have more things to add.

[mvertens]

@TomasTorsvik @matsbn @JorgSchwinger @jmaerz - some of these tasks will no longer be needed once we use the new stream functionality in BLOM. In particular you will not need separate datasets for 2 degree and 1/2 degree. I hope to start implementing this next week. We had decided to move ahead with the 1/2 degree using the older approach since simulations were going to being very soon and we did not want the new implementation holding up the science. However, I hope to have this in place so that we don't need to generate new datasets for 2 degrees and then hopefully move all the resolutions to just interpolation from the original source. At least that is what I think that @matsbn was leaning towards.