How to add a new variable in mod_domfile

[yjin7@masonlive_gmu_edu]

Hi all,I am using CCSM4 F component to do my research. I plan to change the heat flux over the ocean. At first I tried to change the mask (1 for ocean, and 0 for land), say change the mask to -999 over the region where I want to modify the heat flux. However, the model cannot run because the maximum allowable difference of mask is 1. Now I am thinking to add a new variable to mod_domfile (in docn.buildnml.csh) as a "marker". Similarly, change the heat flux where the marker equals, say -999. But I do not know how to modify the source code, e.g., which file should I change to let the model read this new variable?Thanks in advance.