Subject: Model Timestep
From: John B. Eylander (bj@thor.gsfc.nasa.gov)
Date: Thu Aug 03 2000 - 12:31:21 MDT
Hey all,
I have a question about the model timestep of CCM3.6. After working my way
through learning the input variables for CCMEXP and LSMEXP, and trying to
run a test run, I have become a bit confused. What I was looking for was a
model that I could run locally and generate long period datasets (100 years
or so). Using CCM, I performed a test run of 100 days which took about 24
hours on my SGI OCTANE, with dual R12000 300 mHz processors. This seems
like a very long period of time for a climate model, so I again took a look
at the documentation, and found out the model timestep is 20 minutes (at T42
resolution), which seems like a very short period of time for a climate
model (at least to me). At this rate, I figure a 100 year climate run would
take nearly 1 year to calculate!
Is there something I am missing here, or am I correct is assuming that long
term runs (100's of years) should not be accomplished on my desktop SGI, and
only run on a much more powerful Cray? Or am I able to change the timestep
to something a little more do-able, on the order of a few hours (I see in
the documentation the warning about changing the timestep, but I figured I'd
pose the question anyway)? Should I be looking for a different climate
model instead? Thanks for any answers you can throw this way!
John Eylander
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John B. Eylander, Raytheon ITSS
NASA - Goddard Space Flight Center
Code 971.0
John.B.Eylander.1@gsfc.nasa.gov
jeylander@earthlink.net
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