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8.2ka Experimental Design

Page in progress: this is not the final version! Use the discussion panel at the end of the page for comments

Boundary conditions

Summary of 8.2ka boundary conditions

Boundary conditions below are for 8.5 ka (i.e. before lake drainage)

PMIP3/CMIP5	Minimum solution
Orbital parameters	[ ecc = 0.19199 ] - [ obl = 24.222° ] - [ peri-180° = 319.495° ]
Date of vernal equinox	March 21 at noon
Trace gases	[ CO2 = 260 ppm ] - [ CH4 = 660 ppb ] - [ N2O = 260 ppb ] - [ CFC = xxx ] - [ O3 = same as PI ]
Aerosols	Same as PI
Solar constant	1365 W/m2	As in PI
Vegetation	prescribed or interactive as in CMIP5 PI
Ice sheets	Remnant Laurentide ice-sheet (provided*)	Same as PI
Topography and coastlines	Modification of Hudson Bay coastlines (provided*)	Same as PI

*For the ice-sheet reconstruction, see discussion on LGM wiki page

Please use the discussion panel to comment this table!

Freshwater forcing

Two different types of freshwater forcing: the background melt-flux from the Laurentide Icesheet, and the Lake Agassiz drainage. The former supposedly prevented Labrador Sea deep convection (see Hillaire-Marcel et al. 2006 GRL)

Proposed Background Early Holocene melt-water forcing (mandatory)

Flux	0.05 Sv over 500 years
Location	Either part or all of the Labrador Sea (up to the individual modeling groups, as long as it is not added outside the Labrador Sea)

Proposed Lake Agassiz drainage (mandatory):

Fux	2.5 Sv over 1 year
Location	Either part or all of the Labrador Sea (up to the individual modeling groups, as long as it is not added outside the Labrador Sea)
Ensemble	this experiment should be completed at least three times, beginning at different years in the control simulation
Duration	experiment should be integrated until the AMOC recovers, except in the case of unrealistically long (i.e., multicentury) recoveries

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)

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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