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pmip3:design:21k:icesheet:index [2009/09/09 08:19]
pasb
pmip3:design:21k:icesheet:index [2009/09/09 12:16]
jypeter
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 ==== Lev-MOCA ​ ==== ==== Lev-MOCA ​ ====
-=== Northern ​Hemispheric components ​(GLAC-1) ===+=== Northern ​Hemisphere ​(GLAC-1) ===
  
 The Greenland reconstruction is the GrB model described in Tarasov and Peltier( GJI 2002 and JGR 2003). ​ It's a hand tuning of a 3D thermo-mechanically coupled glaciological shallow ice-sheet model and visco-elastic bedrock response model (using the same VM2 rheology used for ICE-5G) to fit the Relative Sea-Level (RSL) observations,​ the GRIP borehole temperature and age profiles, and approximate basal temperatures at CampCentury and Dye3 along with secondary constraints described in the references. ​ The Greenland reconstruction is the GrB model described in Tarasov and Peltier( GJI 2002 and JGR 2003). ​ It's a hand tuning of a 3D thermo-mechanically coupled glaciological shallow ice-sheet model and visco-elastic bedrock response model (using the same VM2 rheology used for ICE-5G) to fit the Relative Sea-Level (RSL) observations,​ the GRIP borehole temperature and age profiles, and approximate basal temperatures at CampCentury and Dye3 along with secondary constraints described in the references. ​
  
-The North American and Eurasian reconstructions are objective Bayesian calibrations of the MUN/UofT glacial systems model (above 3D model plus asynchronously coupled down-slope surface drainage/​lake depth solver, and various other components such as a thermodynamic lake ice, sub-glacial till-deformation,​ ice-shelf represention,​...,​ some of which are described in Tarasov and Peltier, QSR 2004, and Nature 2005, and a more complete description is currently being written up). The calibration involves approximately 30 ensemble parameters to capture ​uncertainties in deglacial ​uncertainties in deglacial climate and ice dynamics. Model runs cover a full glacial cycle. The climate forcing for the calibration is based on interpolation between a glacial state (based on a combination of PMIPI for North America and PMIP II for Eurasia) ​LGM model output temperature and precipitation climatologies along with further regional precipitation controls) and a present-day climatology. The interpolation between glacial and present-day states is weighted to the regional temperature chronology from the tuned Greenland reconstruction. ​ Calibration targets include a large set of RSL observations,​ geologically-inferred deglacial ice-margin chronologies,​ and geodetic constraints. For the case of North America, the calibrated ensemble is further scored with respect to strand-lines (paleo lake level indicators) and Marine Limit (maximum level of marine inundation) observations.+The North American and Eurasian reconstructions are objective Bayesian calibrations of the MUN/UofT glacial systems model (above 3D model plus asynchronously coupled down-slope surface drainage/​lake depth solver, and various other components such as a thermodynamic lake ice, sub-glacial till-deformation,​ ice-shelf represention,​...,​ some of which are described in Tarasov and Peltier, QSR 2004, and Nature 2005, and a more complete description is currently being written up). The calibration involves approximately 30 ensemble parameters to capture uncertainties in deglacial climate and ice dynamics. Model runs cover a full glacial cycle. The climate forcing for the calibration is based on interpolation between a LGM (based on a combination of PMIPI for North America and PMIP II for Eurasia) model output temperature and precipitation climatologies ​(along with further regional precipitation controls) and a present-day climatology. The interpolation between glacial and present-day states is weighted to the regional temperature chronology from the tuned Greenland reconstruction. ​ Calibration targets include a large set of RSL observations,​ geologically-inferred deglacial ice-margin chronologies,​ and geodetic constraints. For the case of North America, the calibrated ensemble is further scored with respect to strand-lines (paleo lake level indicators) and Marine Limit (maximum level of marine inundation) observations.
  
 The data sets for North America and Eurasia will include surface elevation, ice mask, lake depth, surface drainage routing pointer fields and ice flux components of the surface drainage. The data sets for North America and Eurasia will include surface elevation, ice mask, lake depth, surface drainage routing pointer fields and ice flux components of the surface drainage.
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 === Southern hemisphere === === Southern hemisphere ===
  
-Glaciological constraints have shown that the ice5G reconstruction was too high in East Antarctica. Several tests are now made using a revised version of ICE-5G (VM2=ICE-6G) to correct this aspect while keeping the global on see level and other geomorphological constraints. Dick Peltier’s group is working now on smoothing the refine ​model and taking the extension of the loading of the shelf out to a distance from the present coast consistent with a specific bathymetry contour. The final version should be ready by September. ​+Glaciological constraints have shown that the ICE-5G ​reconstruction was too high in East Antarctica. Several tests are now made using a revised version of ICE-5G (VM2=ICE-6G) to correct this aspect while keeping the global on sea level and other geomorphological constraints. Dick Peltier’s group is working now on smoothing the refined ​model and taking the extension of the loading of the shelf out to a distance from the present coast consistent with a specific bathymetry contour. The final version should be ready by September. ​
  
  
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 They are provided for evaluation and test, and do not correspond to the "​official"​ boundary condition to be used for LGM simulations in CMIP5. They are provided for evaluation and test, and do not correspond to the "​official"​ boundary condition to be used for LGM simulations in CMIP5.
  
-Here are also two submitted papers where you can find information about the new ice-sheet that are provided by Dick+ 
 +=== References === 
 + 
 +Note: get in touch with [[pmip2web@lsce.ipsl.fr|Jean-Yves Peterschmitt]] in you need a copy of the following papers. 
 + 
 +  * Peltier, W.R., 2009, //Closure of the budget of global sea level rise over the GRACE Era: The importance and magnitudes of the required corrections for global glacial isostatic adjustment//​. Quat. Sci. Rev. 28, 1658-1674. 
 + 
 +  * Donald F. Argus and W. R. Peltier, 2009. //​Constraining models of postglacial rebound using space geodesy: A detailed assessment of model ICE-5G (VM2) and its relatives//,​ Geophysical Journal International,​ submitted. 
 + 
 +  * W.R. Peltier and R. Drummond, 2008. //​Rheological stratification of the lithosphere:​ A direct inference basd upon the geodetically observed pattern of the glacial isostatic adjustment of the North American continent//​. geophys. res. Lett., vol. 35, L16314, doi:​10.1029/​2008GL034586. 
 + 
 + 
 +=== Data ===
  
 Notes: Notes:
  
 +  * Get in touch with [[pmip2web@lsce.ipsl.fr|Jean-Yves Peterschmitt]] if you want to download the netcdf files used to generate the figures below
   * Click on a figure to get the full size version   * Click on a figure to get the full size version
-  * You can compare the figures with the [[http://​pmip2.lsce.ipsl.fr/​design/​ice5g /​ice5g_v1_1.shtml|ICE-5G v1.1 (PMIP2)]] ​and [[http://​pmip2.lsce.ipsl.fr/​design/​ice5g/​index.shtml|ICE-5G v1.2]] ​versions avalaible on the PMIP2 web site+  * You can compare the figures with the ICE-5G versions available on the PMIP2 web site 
 +    *[[http://​pmip2.lsce.ipsl.fr/​design/​ice5g/​ice5g_v1_1.shtml|ICE-5G v1.1 (PMIP2)]] 
 +    * [[http://​pmip2.lsce.ipsl.fr/​design/​ice5g/​index.shtml|ICE-5G v1.2]] ​
  
 {{:​pmip3:​design:​21k:​icesheet:​ice6g_v1.0_00.0k_1deg.png?​200| 0 K}} {{:​pmip3:​design:​21k:​icesheet:​ice6g_v1.0_00.0k_1deg.png?​200| 0 K}}
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-In September we should be able to compare the results of the revised version of ICE-45G with those of the Lev-Dick collaboration and take a decision based on comparisons with data and on the advice of several specialists+In September we should be able to compare the results of the revised version of ICE-6G with those of the Lev-Dick collaboration and take a decision based on comparisons with data and on the advice of the community 
  ​~~DISCUSSION~~ ​  ​~~DISCUSSION~~ ​
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pmip3/design/21k/icesheet/index.txt · Last modified: 2009/12/23 13:25 by jypeter