CESM1.2.0 CAM4 restart file variable description

[cnrwil004@myuct_ac_za]

Hi all

I am using CESM1.2.0 with a B comp set. It appears that there are no "long names" present for the variables in CAM4 .r. restart netCDF files. I have also been unable to find any documentation elsewhere for the variables in this file. Would it perhaps be possible for someone to give a short description of the variables in such restart files? I am particularly interested in "T_TTEND".

Thank you in advance
-Stefaan-

 

[hannay]

T_TTEND is the total T tendency. It is computed after the parameterizations are computed. 

 

[eaton]

The restart files don't have long_name attributes because they're meant for restarting only, not for analysis.  T_TTEND is a good example of how it is necessary to know the code details to be able to interpret the variable correctly.  In the restart file T_TTEND is a temperature (not a tendency) which is used in the calculation of a tendency when the model is restarted.  State variables that need to be saved from one timestep to the next are typical examples of variables that are written to the restart file.  The total temperature tendency which the T_TTEND variable is use to compute is written to the history file in the variable TTEND_TOT.  See cam_diagnostics.F90 for details. 

 

[cnrwil004@myuct_ac_za]

Thank you Hannay and Eaton for your answers. I apologise; I was not clear in the original message, we are not interested in analysing the output from a restart run, but are investigating the possibilities for producing initial condition ensembles starting from a particular date of a previous run. We were considering trying to apply Gaussian noise to a temperature variable in the restart file, for each of the different ensemble members. It now appears doing a hybrid restart and using pertlim in user_nl_cam to adjust the temperature variable in the cam.i initial condition file, would be more apporpriate and simpler to implement. However, I am still interested in how something (T_TTEND) measured in units of K/s (presumably, as TTEND is) could have values ranging between ~220 and ~310? This seems more like an actual temperature variable than a temporal derivative, or am I misunderstanding something fundamentally? Would it at all be meaningful to perturb variable values in a restart file? Thank you again-Stefaan-