Plans for BLOM/iHAMOCC for NorESM3.0

[TomasTorsvik]

Tentative plans for default (and optional) settings for BLOM/iHAMOCC towards NorESM3.0

When shall MCT support phase out?
Due to changes in the timing of releases of NorESM2.3 and NorESM2.5, fixes in the hybrid coordinates would be good to enter a tag 1.8 of Blom that still supports MCT and could still be used together with NorESM2.3. See also: #439

General

• Maintain, further develop, and document tools for flexible creation of new setups including grids, initial conditions,
  and boundary conditions
• Make pre-defined sets of output size, e.g. blom_outvol = small/medium/large simplified output choices for BLOM #252
  Started for iHAMOCC Output switches for output volumes of iHAMOCC #478 Add a user namelist for reduced output settings #498

BLOM-specific

NorESM 2.3+ (BLOM tag v1.8)

• fix negative tracers in hybrid coordinates due to virtual freshwater fluxes

NorESM 3.0 and beyond

• only mks (default) (remove cgs dependencies)
• 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

NorESM 2.3+ (BLOM tag 1.8)

• 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)
• Write output for limiting nutrient
• Move towards reading N-dep files - only NOy and NHx reading (abondon ndep) Abandon usage of ndep in input files, always read NHx and NOy #492
• Potentially re-introduce N-cycle coupling through MCT Fix N-cycle coupling #506
• Sediment enhancement, optional; ideally would enter tag 1.8 Introducing optional sediment quality-based remineralization #502
• iHAMOCC restart remapping tool - initial version available through Initial version for iHAMOCC restart remapping #476
• Input files for iHAMOCC (N-depsoition, dust & riverine inputs) can be run with MCT (Provide new N-deposition files and used remapping sh-script #486, Add iHAMOCC support for dustflux on tnx0.5 #490, Add river input file for tn0.5v1 grid #505)

NorESM3.0 (envisaged BLOM tag 1.9 or 2.0) - due in INES II by June 2025

• Write output for rivers and any interpolated input fields introduced by Mariana (or for NorESM 3.0+, new CDEPS stream capability to read in forcing files needed by HAMOCC #405)
• New DOC code (first) as optional
• Boundary conditions: CDEPS versus MCT-compatible, iHAMOCC-based, see iHAMOCC support for tnx0.5v1 grid #376, Preparing N-deposition input files for CMIP6 scenarios and historical runs #397, Unify N-deposition input reading #398, time coordinates and file for dust deposition are incorrect for new stream functionality #404, new CDEPS stream capability to read in forcing files needed by HAMOCC #405, always obtain ndep from datm or cam using cmeps/cdeps #410, ndep forcing file is incorrect for most compsets using DATM #411
  Current status Only the technical CDEPS part for N-deposition is incorporated in master (while failing for scenarios ndep forcing file is incorrect for most compsets using DATM #411); N-deposition could serve as guideline for further implementation of CDEPS-based boundary conditions - see new CDEPS stream capability to read in forcing files needed by HAMOCC #405; thus far, iHAMOCC can be still run with NUOPC and iHAMOCC-based boundary conditions (i.e. they are read iHAMOCC internally).
  How we proceed: we aim at continuing the work as laid out in new CDEPS stream capability to read in forcing files needed by HAMOCC #405

NorESM3.0+

• Remove/modify compsets for the extended N cycle (in cime_config/config_component.xml), once MCT is depreciated
• Nitrogen cycling interactive coupling through NUOPC

General iHAMOCC ideas

• Potentially enable to include weathering rates