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<<  default timestep for sld dynamics, http://bb.cgd.ucar.edu//viewtopic.php?t=139 >>

PosterpjrPostedWed Mar 16, 2005 3:58 pm MST, http://bb.cgd.ucar.edu//viewtopic.php?p=411#411
Message: Dear CAM 3.0 users,
<br />
<br />Could any of you tell me what is the default timestep (DTIME) for sld dynamics for different resolutions.
<br />
<br />Thanks and Regards,
<br />sans
<br />The nominal time step for the SLD core is 3600 seconds. 
<br />
<br />The method for determining this should be more transparent, but here
<br />is how things work (at least the last time I looked).
<br />
<br />First the time step is set to a default value within the model.
<br />Then the time can be over-ridden at run time by a value contained in the namelist file.
<br />Whether or not the namelist file contains an over-ride value depends upon two things.
<br />1) the user might have prescribed a value from the time step during the
<br />build-namelist step of the build procedure
<br />2) the build-namelist step might have inserted a value in namelist by itself if you selected some special options during the configuration and build procedure. The special situations are spelled o!
 ut in the .xml files contained in the bld directory of the source tree.
<br />
<br />I am assuming that no special configuration options were chosen, which means the timestep is set at compile time. In that case namelist variables are assigned nominal values in subroutines found in runtime_opts.F90. 
<br />
<br />The relevant calls are to a routine called time_manager_preset (which sets the default value). That value might then be over-ridden when the namelist is read in. If you look at time_manager_preset you will see
<br />dtime = 3600 somewhere in there.
<br />
<br />Phil

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