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topography requirement in LGM

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topography requirement in LGM


I am studying on LGM simulated by CESM1.0.4 using NCAR paleo toolkit and the topography data is from ICE-5G.

1st, For CAM : Since there are three variables: surface altitude,thickness of the ice sheet and ice-mask in ICE-5G, I wonder if I need to add variable "thickness of the ice sheet" to  variable "surface altitude"  as the total topography data which will be read in "cami_create_cesm.csh" to make atmosphere's initial field? 

In addtion, I am using CESM1.0.4. In land model, is it necessary for me to modify fortran code to make variables TOPO_BEDROCK and TOPO_ICE different  in ""  considering that  there is thickness of the ice sheet (land ice) in LGM since there are annotations (below) in "paleo_mkraw_ccsm4.F90"? And what is the meaning of " glacier multiple elevation class"?

Wating for your answer. Thanks


                                                                                                                                                                                              Taily Zhang

Annotations  in "paleo_mkraw_ccsm4.F90"


! read topo from topo_depth file

! add code to specify ice sheet if so desired

! if you wish to read in a seperaete ice sheet topofile, 

! you will need to modify the code


 topo_ice = topoin

 topo_bedrock = topoin




Below is the attribute of the data in ICE-5G


 float orog(lat, long) ;

     orog:comment = "ICE-5G: version = 1.2 - time = 21 KBP" ;

     orog:long_name = "Surface Altitude" ;

     orog:standard_name = "surface_altitude" ;

      orog:units = "m" ;

float sftgit(lat, long) ;

       sftgit:comment = "ICE-5G: version = 1.2 - time = 21 KBP" ;

       sftgit:long_name = "Thickness of the Ice Sheet" ;

       sftgit:standard_name = "land_ice_thickness" ;

       sftgit:units = "m" ;

float sftgif(lat, long) ;

       sftgif:comment = "ICE-5G: version = 1.2 - time = 21 KBP" ;

       sftgif:long_name = "Ice-mask" ;

       sftgif:standard_name = "Ice-mask" ;

       sftgif:units = "%" ;


Dear Taily Zhang -

Thank you for your interest in using CESM for your study of the LGM.  Unfortunately, we do not have the resources to support CESM1.0.4 for paleoclimate simulations.  However, we have limited online documentation for CESM1.2+ ( to help guide paleo climate research.  Note, the LGM is considered a 'near-modern' simulation, so many of the deep time paleo tools (including paleo_mkraw) will not be the best choice for a near-modern simulation.  


Dear Tally Zhang,


This paper might be helpful

Brady, E.C., B.L. Otto-Bliesner, J.E. Kay, and N. Rosenbloom, 2013:  Sensitivity to glacial forcing in the CCSM4. Journal of Climate, 26, 1901-1924.

Also the PMIP3 website



Dear Otto-Bliesner,

Thanks for your help.  Besides,I have read many of your articles which inspired me a lot. Thanks.


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