This is an old revision of the document!
Design for the Last Deglaciation experiment
Associated publications
Version 1: Ivanovic et al. (2015 and in revision) GMD
Version 1 Specifications
Last Glacial Maximum Spinup (21 ka)
This spinup simulation is compatible with the PMIP4-CMIP6 LGM experiment, which can also be used as the initialisation state for the fully transient run from 21 ka onwards, provided the ICE-6G_C or GLAC-1D ice sheet reconstructions and associated boundary conditions (orography, coastlines and bathymetry) were used.
PMIP4 specifications | |
---|---|
PMIP4 name | LDv1-LGMspin |
Astronomical parameters | eccentricity = 0.018994 obliquity = 22.949° perihelion-180° = 114.42° Date of vernal equinox : Noon, 21st March |
Solar constant | 1361.0 ± 0.51365 W m-2 |
Trace gases | CO2 = 190 ppm CH4 = 375 ppb N2O = 200 ppb CFC = 0 O3 = Preindustrial (e.g. 10 DU) |
Ice sheets, orography and coastlines | 21 ka data from either - ICE-6G_C reconstruction [Access to data] - GLAC-1D reconstruction [Access to data] |
Bathymetry | Keep consistent with the coastlines, using either: - Data associated with the ice sheet - Preindustrial bathymetry |
Global ocean salinity | + 1 psu, relative to preindustrial |
All others | As per the PMIP4-CMIP6 LGM experiment |
Transient orbit and trace gases Sspinup (26-21 ka)
This option for spinning-up the last deglaciation simulation uses transient orbital parameters and trace gases from 26-21 ka.
PMIP4 specifications | |
---|---|
PMIP4 name | LDv1-transpin |
Astronomical parameters | All orbital parameters should be transient as per Berger (1978) 26-21 ka |
Trace gases | All adjusted to the AICC2012 chronology (Veres et al., 2013) 26-21 ka: CO2 = Transient, as per Bereiter et al. (2015) CH4 = Transient, as per Loulergue et al. (2008) N2O = Transient, as per Schilt et al. (2010) |
All others | As per the LGM (21 ka) spinup type; LDv1-LGMspin |
Transient deglaciation (21-0 ka)
These are the specifications for the full transient run 21-0 ka. (Note, the period of focus for the experiment is 21-9 ka, but all boundary conditions are provided until 0 ka so that groups can extend the run to present if they wish).
PMIP4 specifications | |
---|---|
PMIP4 name | LDv1 |
Initial conditions (pre 21 ka) | Recommended (optional) to use either: - LDv1-LGMspin - LDv1-transpin See above for details. The method must be documented, including information on the state of spinup |
Astronomical parameters | Transient, as per Berger (1978) |
Solar constant | 1361.0 ± 0.51365 W m-2 |
Trace gases | Adjusted to the AICC2012 chronology (Veres et al., 2013) 21-0 ka: CO2 = Transient, as per Bereiter et al. (2015) CH4 = Transient, as per Loulergue et al. (2008) N2O = Transient, as per Schilt et al. (2010) CFC = 0 O3 = Preindustrial (e.g. 10 DU) |
Ice sheet | Transient, with a choice of either : - ICE-6G_C reconstruction [Access to data] - GLAC-1D reconstruction [Access to data] How often to update the ice sheet is optional |
Orography and coastlines | Transient. To be consistent with the choice of ice sheet. Orography is updated on the same timestep as the ice sheet. It is optional how often the land-sea mask is updated, but ensure consistency with the ice sheet reconstruction is maintained |
Bathymetry | Keep consistent with the coastlines, and otherwise use either: - Data associated with the ice sheet; it is optional how often the bathymetry is updated - Preindustrial bathymetry |
River routing | Ensure that rivers reach the coastline It is recommended (optional) to use one of the following: - Preindustrial configuration for the model - Transient routing provided with the ice sheet reconstruction (if available) - Manual/model calculation of river network to match topography |
Freshwater fluxes | At participant discretion. Three options are: melt-uniform, melt-routed and no-melt: - Melt-uniform : use a globally uniform ice meltwater flux, e.g. as associated with one of the ice sheet reconstructions [Access to data] - Melt-routed : use a routed ice meltwater flux, e.g. as associated with one of the ice sheet reconstructions [Access to data] - No-melt : have no ice sheet meltwater in the simulation It is recommended (optional) to run at least one Core simulation with a scenario consistent with the chosen ice sheet reconstruction to conserve salinity. |
Vegetation & land cover Aerosols (dust) | Prescribed preindustrial cover or dynamic vegetation model Prescribed preindustrial distribution or prognostic aerosols |