1. Ronald J Stouffer October 2015
GFDL CMIP6 Plans
Ronald J Stouffer
October 2015

2. New GFDL Model* “CM4”, “ESM4”
1degL48 atm full chemistry or 1/2degL32 fast chemistry
1/4deg MOM6 ocean+BGC (COBALT)
“LM3+” land
“SIS2” sea ice
* Details (resolution and etc.) depend on availability of resources

3. Atmospheric component “AM4”
New convection scheme (double plume – shallow and deep - Bretherton)
Lock or TKE PBL – testing -TBD
Newer version of FV core – FV3
Cloud physics –
Microphysics – single moment (eg CM3, Donner et al. 2011)
Macrophysics - Tiedtke
Fast chemistry
Few prognostic variables (dust, sea salt, BC, OC, sulfate aerosols)
Full chemistry
~100 prognostic variables, ~60 advected

4. Ocean “MOM6”
Complete rewrite of code, open shared development via GitHUB
C-grid – better choke points, no X-land mixing
ALE in vertical – no vert time step limitations
Z-coor developed/tuned, HYCOM-like vertical coor being tested
Improved numerics
Little numerical diapycnal mixing (grid dependent)
Most (all?) diapycnal mixing explicit

5. Land “LM3+” Similar to land model in our CMIP5 models
Subgrid hillslope tiles and groundwater updated
New LM4 model delivered in next year or so
New vegetation dynamics (PPA) and urban tiles
C & N cycles in plants, soils, rivers
New soil BGC with microbes

6. Sea Ice “SIS2” Complete rewrite of SIS1 – conservation improved
C-grid – better representation of channels
Vertical physics shared with CICE
Fixes several numerical instabilities
Bergs – adding tabular to CMIP5 point bergs
Coming …..
Sea ice will be re-embedded in ocean => hope to fix remaining numerics issues.
Land ice – ocean interfacing

7. GFDL CMIP6 Issues/Concerns
Will all CMIP6 models/MIPs follow the OMIP protocol for archived variables?
Regular updated historical forcings as near to real time as possible.
Some MIP data requests seem impractical - way too large – C4MIP as example, but there are others
Seem to be many “hidden” runs in design
Hidden == not explicitly in priorities but needed to make priority runs (C4MIP (e.g. emission), FAMIP, …)