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--- pmip3:design:pi:final:icesheet [2009/12/02 18:51] – pasb
+++ pmip3:design:pi:final:icesheet [2009/12/04 14:19] – pasb
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 Several documents and figures, as well as discussion and comments from the community can be found on the PMIP ice-sheet discussion page [[pmip3:design:21k:icesheet:index|Ice Sheet discussion]]
+===== Ice-sheet reconstruction to be used for PMIP3/CMIP5 simulations =====
 ===== Documentation of the different ice-sheet reconstructions =====
+For those interested in sensitivy experiments below is more details of the different ice-sheets anf the acess to the corresponding files.
 ==== ICE-6G ====
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   * Get in touch with [[pmip2web@lsce.ipsl.fr|Jean-Yves Peterschmitt]] if you want to download the netcdf files
-<note tip>You should download the {{:pmip3:design:21k:icesheet:ice-ng_compare_polar.pdf}} file if you want to look at detailed graphics comparing the different versions of ICE-nG (56 Mb, 77 pages)</note>
+A comparison between the different versions of ICE-nG is provided on the pdf document {{:pmip3:design:21k:icesheet:ice-ng_compare_polar.pdf}}(56 Mb, 77 pages)
 ==== Northern Hemisphere (GLAC-1) ====
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 === Data ===
-<note warning>Note that the North Am model is calibrated with a stub Greenland by Ellesmere. When a final model is chosen, the North American and Greenland models can be easily melded.\\ \\ Also, please note, that none of the above have yet been published, so these files are provided for discussion and consideration. Any fields and data not selected as a PMIP boundary condition are not to be used for research without prior consent.</note>
   * Get in touch with [[lev@mun.ca|Lev Tarasov]] or [[pmip2web@lsce.ipsl.fr|Jean-Yves Peterschmitt]] if you want to download the following NetCDF files:
-    * NetCDF of 21 to 10ka surface elevation, thickness, basal velocities for the nn9021 North Am model and nn8234 Eurasian model: **NAnn9021.nc**, **EAnn8234.nc**
+    * NetCDF of 21 to 10ka surface elevation, thickness, basal velocities for the nn454 North Am model and nn8234 Eurasian model: **NAnn454.nc**, **EAnn8234.nc**
     * NetCDF of 21 to 10ka for nn445  ensemble means and 1.5 sigma range: **NAnn445.nc**
   * Other data available upon request from [[lev@mun.ca|Lev Tarasov]]
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 Broadly, the first iterations are based on the analyses of far-field data where the sea-level signal is predominantly a measure of the changes in total ice volume (the ice-volume equivalent sea level or esl) with the principal isostatic component often being the water-load term and a function of the rate at which water is added into or removed from the oceans.  Simple models are initially used for the ice sheets.  The separation of mantle rheology from the esl function is achieved by using the spatial variability of the far-field sea-level signals (Nakada and Lambeck, 1990 #127 see http://rses.anu.edu.au/people/lambeck_k/index.php?p=pubs for references).  The resulting ice function is then redistributed between the ice sheets by using simple scaling relations in the first place and the process is iterated to ensure some convergence (Lambeck, Yokoyama and Purcell, 2002 # 228).
+In parallel inversions are attempted for the individual ice sheets using data from within and close to the ice margins.  These observations are most sensitive to the ice models and mantle rheology.  For the northern hemisphere these analyses are carried out separately for Scandinavia (Lambeck, Smither, and Johnston, 1998 #187, Lambeck et al., in press), Barents-Kara (Lambeck, 1995, 1996 #166, 170), Greenland (Fleming and Lambeck, 2004 #238), British Isles (Lambeck, 1993; 1995 #164, 156) and North America (as yet unpublished).  In all cases new compilations of the field data have been made.  These separate solutions allow for lateral variability in mantle viscosity.  Some interactions between the ice sheets occur and the solutions are therefore iterated.
+The Antarctic field data is insufficient for a similar analysis for the southern hemisphere and we use the difference between the global esl and the northern hemisphere esl to estimate the volume changes for Antarctica eslant (allowing for mountain deglaciation in both hemispheres, Lambeck and Purcell, 2005 #247).  The ice in Antarctica is then distributed according to the LGM ice margins proposed by Anderson et al. (2002) and on the assumption that the ice profiles followed the quasi-parabolic function proposed by Paterson.  The retreat history is determined by the eslant function.  These models are not meant to be accurate reflections of the Antarctic ice history but as a convenient way of disposing of the ice volume that cannot be attributed to the northern hemisphere, in a way that will not impact in a major way on the far-field and northern hemisphere analyses.
+With the new ice models the far-field analysis is repeated and the individual ice sheet analyses are also repeated.  Several such iterations have now been carried out but the successive results have not yet been published.  The LGM results provided here represent the most recent (2009) solution.  The full solutions for some of the ice sheets extend back to MIS-6 (Lambeck et al., 2006 # 252).
+The rebound inversions result in the changes in ice thickness compared to the present day ice volumes.  Thus the LGM ice thickness is obtained by adding the present-day ice thickness.  The LGM ice elevation, with respect to sea level at the LGM is obtained by subtracting the sea-level change (geoid change beneath the ice sheet) from the palaeo ice thickness.
+The esl function as used in the ANU solutions is defined as all land ice and grounded ice on the shelves and the ocean margin at the LGM is defined by the ice grounding line (Lambeck et al., 2003 #233).
+=== References ===
+  * Lambeck & Johnston, 1998: The viscosity of the mantle: evidence from analyses of glacial rebound phenomena. "The Earth's Mantle" (ed. I. Jackson). Cambridge University Press, Cambridge. pp 461-502
+  * Lambeck, Purcell, Johnston, Nakada & Yokoyama, 2003: Water-load definition in the glacio-hydro-isostatic sea-level equation. Quaternary Science Reviews, vol. 22, pp 309-318
+  * Lambeck, & Chappell, 2001: Sea level change through the last glacial cycle. Science, 292, 679-686.
+  * Lambeck, Yokoyama & Purcell, 2002: Into and out of the Last Glacial Maximum: sea-level change during Oxygen Isotope Stages 3 & 2. Quaternary Science Reviews, vol. 21, pp 343-360
+==== Plots of the different ice-sheets ====
+The following plots have been prepared by [[abeouchi@ccsr.u-tokyo.ac.jp|Ayako Abe-Ouchi]] and [[saitofuyuki@jamstec.go.jp|Saito Fuyuki]]:
+  * {{:pmip3:design:21k:icesheet:gaa5.pdf|Antarctica}} plots
+  * {{:pmip3:design:21k:icesheet:gnh5.pdf|Northern Hemisphere}} plots
+The plots show the combined //Surface Altitude// and //Fraction of Grid Cell Covered with Glacier//, and use data from:
+  * for ANU ice model (2009)
+  * for ICE-6G v1.02
+  * for GLAC-1 nn454 model for North America, and ne8234 for Eurasia