[MITgcm-support] synchronous vs asynchronous integrations

[David Wang]

Hello,

I ran two model runs with the same configuration, the same initial 
fields and the same surface forcing fields, but different timesteps (one 
is sychronous: deltaT = 3600s; another is asynchronous: deltaTmom = 
900s, deltaTtracer = deltrTClock = 10800s). They give considerably 
different results, which is not what I expected. Of course I prefer the 
asychronous one since it takes much less integration time, but the 
differences make me to doubt the integrity of these runs.

The model domain is the tropical pacific. The initial fields are 
climatological potential temp and salinity. The model is forced by 
climatological monthly forcings. kpp, gmredi, rbcs packages are used.

I'm attaching my data namelist file and a plot of momKE_ave timeseries 
over the first model year (which is to show how different they are. blue 
is the sychronous run and red is the asychronous run). The temperature 
field snapshots at the end of the first model year also differ, esp. 
near the equator.

If anyone would have any ideas on what might go wrong, plz let me know. 
Thanks very much.

- d.
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