pmip3:design:21k:final
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pmip3:design:21k:final [2010/02/05 13:36] – jypeter | pmip3:design:21k:final [2010/03/26 15:14] – jypeter | ||
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====== 21ka Experimental Design====== | ====== 21ka Experimental Design====== | ||
- | ===== Boundary conditions | + | ===== Summary table ===== |
- | ==== Summary of 21ka boundary conditions ==== | + | The changes listed in this table are //with respect to the [[pmip3: |
^ ^ | ^ ^ | ||
| Orbital parameters | | Orbital parameters | ||
| Date of vernal equinox | | Date of vernal equinox | ||
- | | Trace gases | [ **CO< | + | | Trace gases | [ **CO< |
- | | Aerosols | + | | Aerosols |
| Solar constant | | Solar constant | ||
| Vegetation | | Vegetation | ||
- | | Ice sheet | + | | Ice sheets |
- | | | + | | |
- | | Ocean bathymetry | + | | Ocean bathymetry |
- | | River outflow | + | | River outflow |
- | | Ice sheet ice stream | + | | Ice sheet mass balance |
- | | Mean ocean salinity | + | | Mean ocean salinity |
+ | | Mean atmospheric surface pressure | ||
+ | |||
+ | ===== Boundary conditions ===== | ||
==== Insolation ==== | ==== Insolation ==== | ||
- | Note that insolation should follows PMIP requirements. Please check it carefuly using the following tables ([[http:// | + | Note that insolation should follows PMIP requirements. Please check it carefuly using the following tables ([[http:// |
- | Check carefully the date of the Vernal equinox, because it has implications | + | Check carefully the date of the Vernal equinox, because it has implications |
- | ==== Ice-sheet ==== | + | ==== Ice-sheets and related changes |
- | The ice sheet provided for PMIP3/CMIP5 LGM experiments is a blended product obtained by averaging three different ice sheets: | + | The ice sheet provided for PMIP3/CMIP5 LGM experiments is a blended product obtained by averaging three different ice sheets: |
- | * ICE6G provided by Dick Peltier | + | |
- | * MOCA provided by Lev Tarasov | + | Data files are available on the [[pmip3: |
- | * ANU provided by Kurt Lambeck | + | |
- | A short description and references for the different | + | Implementing |
- | [[pmip3: | + | |
- | This solution was proposed by PMIP bureau in light of a community checking. Given the uncertainties that still exist on the reconstruction of the ice-sheet, resulting from uncertainties in datation for the data used for global or regional constraints, | + | === Land-sea mask === |
- | The ice sheet should be implemented following PMIP2 protocol by considering | + | This mask should be prescribed using the data provided |
- | + | ||
- | \\ \\ Data files are available on the [[pmip3: | + | |
- | ==== Land-sea mask ==== | + | If this proves difficult for a modelling group, the **__minimum__** implementation is to: |
+ | * fill in the Hudson Bay and the Barents sea, which were covered by the main northern hemisphere ice-sheets. | ||
+ | * close the Bering Strait (by changing the land-sea mask or imposing zero flux on water and sea-ice across the Bering Strait). | ||
+ | * make sure that the ocean model configuration keeps the following straits open: | ||
+ | * Denmark Strait (between Greenland and Ireland). | ||
+ | * Gibraltar Strait. | ||
+ | * //Indonesia Strait// (//check exact name with Olivier Marti//?). | ||
- | The land-sea mask is provided by the ICE6G model, except for Antarctica where you should deduce it from the averaged ice-sheet. | + | === Land surface elevation === |
- | \\ Data files are available on the [[pmip3: | + | The change in surface elevation specified by the '' |
+ | Note: this specified change assumes that the surface elevation over present-day oceans is zero (m). | ||
- | The minimum change is to close the Bering Strait by changing the land-sea mask or imposing rero flux on water and sea-ice | + | === Ice-sheet extent === |
+ | |||
+ | The ice-sheet extent (aka //land-sea mask//) should be prescribed using the data provided in [[target.nc|file.nc]], | ||
+ | * The ice shelves can be defined from the '' | ||
+ | * Groups implementing the provided ice shelves should keep the Greenland-Iceland ridge open in the ocean configuration. | ||
+ | |||
+ | === Ocean bathymetry === | ||
+ | |||
+ | The mean sea-level change corresponding to the ice-sheet reconstruction to be used in the PMIP3 LGM experiment is approximatively NNN m. A more complete description of the change in bathymetry can be computed from the Peltier [[https:// | ||
+ | |||
+ | The ocean bathymetry will be adapted by each group, depending on the flexibility of their ocean model. | ||
+ | |||
+ | Modelling groups should pay special attention to: | ||
+ | * The bathymetry should be zero under the grounded ice-sheets. | ||
+ | * ... (see also the other ocean model configuration checks in this section). | ||
==== River outflow ==== | ==== River outflow ==== | ||
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You can use the river routing provided by Lev Tarasov to change the routing scheme in your code, so that the river pathways is consistent with the presence of the ice-sheet. | You can use the river routing provided by Lev Tarasov to change the routing scheme in your code, so that the river pathways is consistent with the presence of the ice-sheet. | ||
- | \\ Data files are available on the [[pmip3: | + | \\ Data files are available on the [[pmip3: |
==== Ice-sheet mass balance ==== | ==== Ice-sheet mass balance ==== | ||
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==== For Earth System Models with interactive carbon cycle ==== | ==== For Earth System Models with interactive carbon cycle ==== | ||
- | The simulations should be forced by the prescribed LGM CO2 concentrations. Please use the same protocol as in CMIP5 to store the diagnostic carbon fluxes and the variables needed for PCMIP (see | + | The simulations should be forced by the prescribed LGM CO< |
- | [[http:// | + | [[http:// |
==== Dust forcing ==== | ==== Dust forcing ==== | ||
- | Some ESM have interative | + | Some ESM have interactive |
===== Initial conditions ===== | ===== Initial conditions ===== | ||
- | The surface pressure field must be adjusted to the change in surface elevation over the continents. | ||
- | This can be done: | ||
- | * either by gradually changing the surface elevation in order to avoid generating gravity waves, | ||
- | * or by adjusting the initial pressure field to the LGM surface elevation. | ||
- | If you choose the second option, you must be careful to conserve atmospheric mass. | ||
- | The spin up procedure is up to group, following CMIP5 approach | + | * Mean ocean salinity: add +1 PSU everywhere once, at the beginning of the simulation. |
+ | |||
+ | * The surface pressure field must be adjusted | ||
+ | * either by gradually changing the surface elevation in order to avoid generating gravity waves, | ||
+ | * or by adjusting the initial pressure field to the LGM surface elevation.\\ | ||
- | Note several groups share the same ocean models for which an initial state can be provided | + | * The spin up procedure is up to each group, following CMIP5 approach or from a previous cold state. |
- | If you need an initial state from a other group, you can contact | + | * Note several groups share the same ocean models for which an initial state can be provided from PMIP2 experiments.\\ |
- | Groups with high resolution model for which it is too difficult to run long simulations should contact Olivier.marti@lsce.ipsl.fr to find the best alternative solution. | + | * Groups with high resolution model for which it is too difficult to run long simulations should contact |
\\ \\ \\ | \\ \\ \\ |
pmip3/design/21k/final.txt · Last modified: 2010/12/07 00:38 by jypeter