PMIP3 Boundary Conditions

Pre-industrial control run

Vegetation

OA = fixed

OAV = interactive

Ice sheets

Modern

Topography, coastlines

Modern

Greenhouse gases

Pre-industrial concentrations (around 1750)

CO2 = 280 ppm

CH4 = 760 ppb

N20 = 270 ppb

CFC = 0

03 = Modern - 10 DU

Insolation

Solar constant = 1365 W m-2

Eccentricity = 0.016724

Obliquity = 23.446 °

Angular precession = 102.04 °

Initial ocean state

Modern

Initialize 3-D ocean temperature and salinity from the Levitus 1998 datasets

Model spinup

Each group has its own spinup methodology, which we ask they document.

The model should be run long enough for any trends to be small, and the control run should be at least as long as any anomaly integrations.

Mid-holocene

Vegetation

OA = Same as control run

OAV = interactive

Ice sheets

Same as control run

Topography, coastlines

Same as control run

Greenhouse gases

CO2 = 280 ppm

CH4 = 650 ppb

N20 = 270 ppb

CFC = 0

03 = Same as control run

Insolation

Solar constant = 1365 W m-2 (Same as control run)

Eccentricity = 0.018682

Obliquity = 24.105 °

Angular precession = 0.87 °

Initial ocean state

Initialize 3-D ocean temperature and salinity either from the Levitus 1998 datasets or from year 100 of the control run

Model spinup

Same as control run

Last glacial maximum

Vegetation

OA = Same as control run

OAV = interactive

Ice sheets

ICE-5G v1.1

Topography, coastlines

From ICE-5G v1.1 data set

Greenhouse gases

CO2 = 185 ppm

CH4 = 350 ppb

N20 = 200 ppb

CFC = 0

03 = Same as control run

River outflow

Modified according to a river pathway map

Ice sheet melt

Same as control run, or add excess LGM freshwater

Insolation

Solar constant = 1365 W m-2 (Same as control run)

Eccentricity = 0.018994

Obliquity = 22.949 °

Angular precession = 114.42 °

Initial ocean state

Mean ocean salinity = Same as control run

Option 1: same as for control run (warm ocean state)

but see model spinup below

Option 2: cold ocean state from existing LGM simulation

Model spinup

If initializing from modern conditions (Option 1):

Option 1a: we recommend doing a 100-year Haney forced run, restoring the SSTs to those of a slab model LGM anomaly SSTs.

Option 1b: or 100-year Haney forced run, restoring to CLIMAP LGM anomaly SSTs.

Option 1c: or ocean-only stage restoring SSTs to slab or CLIMAP LGM

Option 1d: or just run it (brute force approach)!

For both Options 1 and 2:

Run the OAGCM (initialized from either the end of Option 1, or from the cold state of an existing LGM simulation) for long enough for any trends to be small.

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