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6ka Experimental Design

Boundary conditions

Summary of 6ka boundary conditions

PMIP3/CMIP5
Orbital parameters	[ ecc = 0.018682 ] - [ obl = 24.105° ] - [ peri-180° = 0.87° ]
Date of vernal equinox	March 21 at noon
Trace gases	[ CO2 = 280 ppm ] - [ CH4 = 650 ppb ] - [ N2O = 270 ppb ] - [ CFC = 0 ] - [ O3 = same as PI ]
Aerosols	Same as PI
Solar constant	Same as PI
Vegetation	prescribed or interactive as in CMIP5 PI
Ice sheets	Same as PI *
Topography and coastlines	Same as PI *

* Sensitivity experiments will be proposed as part of a working group to test the uncertainties due to the remnant ice-sheet. If you are interested to participate to this working group contact Pascale Braconnot

Vegetation

The vegetation should be treated as in the CMIP5 PI experiment. The reason is that in CMIP5 we test the version of the model used for future climate projections. Since OA and ESM models will be considered, depending on the model used the vegetation will be

prescribed to PI (which means both vegetation types and LAI are prescribed )

Prescribed to PI with interactive LAI (models with interactive carbone cycle, but no vegetation dynamics)

Computed by the model (models with dynamic vegetation)

There are still questions concerning the possibility to have a 6ka reconstructed vegetation from a combination of model output and data analyses that could be used for sensitivity experiments. Please tell if you are interested by such a map and what would be the best variables (pft?) that should be provided (see comment from B. Otto-Bliesner in the discussion pannel).

For Earth System Models with interactive carbone cycle

The simulations are forced by CO2 concentrations. Please use the same protocol as in CMIP5 to store the carbone fluxes and the variables needed for PCMIP (see list here)

Insolation

Note that insolation should follows PMIP requirements. Please check it carefully using the following tables (6ka BP insolation tables)

Initial conditions

PMIP3	Alternative solution
Initial conditions	Branch off PI after adjustement	Same as in PI
Model spin up	Same as in PI

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