Table of Contents
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Last Interglacial Experimental Design
Goal
Run early Eemian, mid-Eemian and glacial inception snap shots. This will allow us to model the high latitude response to obliquity maximum (130ka) and minimum (115ka), and near precession optimum for ITCZ shift, ENSO and tropical monsoons (125ka)
Core experiments
130ka, 125ka and 115ka time slices with ocean-atmosphere models. If only one Last Interglacial experiment is carried out, 130ka is the top priority.
Extra experiments
- 128ka
- repeat core and 128ka experiments with equivalent ocean-atmosphere-vegetation models
- repeat 130ka experiment with a higher value of CO2, to account for possible dating uncertainties and to assess the impact of the relatively low CO2 in the core experiment. (contact Bette Otto-Bliesner if interested)
- Ice-sheet reconstruction sensitivity
- Reduced Greenland ice-sheet, possibly using the model reconstruction of Otto-Bliesner et al (2006) (contact Bette Otto-Bliesner if interested).
- Reduced West Antarctic ice-sheet (contact Bette Otto-Bliesner if interested).
- transient interglacial simulations: 130-125ka (or 130-115ka). Either low resolution model or GCM with accelerated boundary conditions, using transient orbit and trace gases (contact Dan Lunt if interested).
- transient holocene simulations: 8-2ka (or 8-0ka). Either low resolution model or GCM with accelerated boundary conditions, using transient orbit and trace gases (contact Dan Lunt if interested).
- transient and snapshot simulations with variable solar forcing (contact Hans Renssen and/or Steven Phipps if interested)
Boundary conditions
130ka (CORE - TOP PRIORITY)
| PMIP3 | Alternative solution | |
|---|---|---|
| Orbital parameters | [ ecc = 0.038209 ] - [ obl = 24.242° ] - [ peri-180° = 228.32° ] | |
| Date of vernal equinox | March 21 at noon | |
| Trace gases | [ CO2 = 257 ppm ] - [ CH4 = 512 ppb ] - [ N2O = 239 ppb ] - [ CFC = 0 ] - [ O3 = Same as PI ] | |
| Aerosols | Same as PI | |
| Solar constant | 1365 W/m2 | As in PI |
| Vegetation | Pre-industrial fixed | |
| Ice sheets | Same as PI | |
| Topography and coastlines | Same as PI |
128ka (EXTRA)
| PMIP3 | Alternative solution | |
|---|---|---|
| Orbital parameters | [ ecc = 0.039017 ] - [ obl = 24.131° ] - [ peri-180° = 259.65° ] | |
| Date of vernal equinox | March 21 at noon | |
| Trace gases | [ CO2 = 275 ppm ] - [ CH4 = 709 ppb ] - [ N2O = 266 ppb ] - [ CFC = 0 ] - [ O3 = Same as PI ] | |
| Aerosols | Same as PI | |
| Solar constant | 1365 W/m2 | As in PI |
| Vegetation | Pre-industrial fixed | |
| Ice sheets | Same as PI | |
| Topography and coastlines | Same as PI |
125ka (CORE)
| PMIP3 | Alternative solution | |
|---|---|---|
| Orbital parameters | [ ecc = 0.040013 ] - [ obl = 23.798° ] - [ peri-180° = 307.14° ] | |
| Date of vernal equinox | March 21 at noon | |
| Trace gases | [ CO2 = 276 ppm ] - [ CH4 = 640 ppb ] - [ N2O = 263 ppb ] - [ CFC = 0 ] - [ O3 = Same as PI ] | |
| Aerosols | Same as PI | |
| Solar constant | 1365 W/m2 | As in PI |
| Vegetation | Pre-industrial fixed | |
| Ice sheets | Same as PI | |
| Topography and coastlines | Same as PI |
115ka (CORE)
| PMIP3 | Alternative solution | |
|---|---|---|
| Orbital parameters | [ ecc = 0.041421 ] - [ obl = 22.405° ] - [ peri-180° = 110.88° ] | |
| Date of vernal equinox | March 21 at noon | |
| Trace gases | [ CO2 = 273 ppm ] - [ CH4 = 472 ppb ] - [ N2O = 251 ppb ] - [ CFC = 0 ] - [ O3 = Same as PI ] | |
| Aerosols | Same as PI | |
| Solar constant | 1365 W/m2 | As in PI |
| Vegetation | Pre-industrial fixed | |
| Ice sheets | Same as PI | |
| Topography and coastlines | Same as PI |
Transient 130ka-125ka (EXTRA)
| PMIP3 | Alternative solution | |
|---|---|---|
| Orbital parameters | varying, model interpolates values given on a 1k resolution. See values here: http://www.paleo.bris.ac.uk/~ggdjl/pmip/orbit_pmip.out Values are given for 132-115ka. | |
| Date of vernal equinox | March 21 at noon | |
| Trace gases | varying, model interpolates values given on a 0.1k resolution. See values here: http://www.paleo.bris.ac.uk/~ggdjl/pmip/pmip_hol_lig_gases.txt Values are given for 132-115ka. | |
| Aerosols | Same as PI | |
| Solar constant | 1365 W/m2 | As in PI |
| Vegetation | Pre-industrial fixed | |
| Ice sheets | Same as PI | |
| Topography and coastlines | Same as PI |
Transient 8ka-2ka (EXTRA)
| PMIP3 | Alternative solution | |
|---|---|---|
| Orbital parameters | varying, model interpolates values given on a 1k resolution. See values here: http://www.paleo.bris.ac.uk/~ggdjl/pmip/orbit_pmip.out Values are given for 10-0ka. | |
| Date of vernal equinox | March 21 at noon | |
| Trace gases | varying, model interpolates values given on a 0.1k resolution. See values here: http://www.paleo.bris.ac.uk/~ggdjl/pmip/pmip_hol_lig_gases.txt Values are given for 10-0ka. | |
| Aerosols | Same as PI | |
| Solar constant | 1365 W/m2 | As in PI |
| Vegetation | Pre-industrial fixed | |
| Ice sheets | Same as PI | |
| Topography and coastlines | Same as PI |
Notes
- Trace gas information was obtained from ice core data, all on the EDC3 chronology. For more information (including figures) and details (including IDL code) of the interpolation, please see the webpage below (including a readme file)
http://www.paleo.bris.ac.uk/~ggdjl/pmip
- Orbital values from Berger (1978). Calculated using B78 fortran code downloadable from http://www.astr.ucl.ac.be/index.php?page=AstronomicalInsolationForcing
- Some models may calculate their own orbital parameters internally, which is fine.
- For accelerated simulations, the trace gases and orbits are identical to the non-accelerated simulations, but have a smaller timestep.
Initial conditions
For snapshots:
| PMIP3 | Alternative solution | |
|---|---|---|
| Initial conditions | Branch off PI after adjustment | Same as in PI |
| Model spin up | Same as in PI |
For transients:
| PMIP3 | Alternative solution | |
|---|---|---|
| Initial conditions | Branch off PI after adjustment | Same as in PI |
| Model spin up | 2kyr or less before transient starts | Same as in PI |
For initial conditions, and especially spinup, the key thing is to document what you do!
For the transient simulations, orbits and trace gas values are given for up to 2ky before the start date of the simulation.
Participating groups
The following groups intend to perform experiments for the Eemian interglacial sub-project
BRIDGE, Bristol, UK
People involved: Joy Singarayer, Paul Valdes, Dan Lunt
We plan to use HadCM3 and HadGEM2 (the version being used for IPCC simulations) to perform the core interglacial OA experiments. HadCM3 will be used for the optional further snap-shot simulations, and FAMOUS for transient Eemian simulations
Kiel University, Kiel, Germany
People involved: Brigit Schneider, Wonsun Park, Liya Jin, Uta Krebs-Kanzow
We plan to use KCM to carry out snapshots at 115k, 122k, 126k and 130k, and the transients (with 10* accelerated forcings, and constant greenhouse gases).
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