[MITgcm-support] pickup c52 to c54

[Jean-Michel Campin]

Hi Stephanie,

> Hi -
> I have a pickup file created by a c52 run...
> and now trying to run with c54 there are problems
> with the pickup: e.g. salt fields have temperature
> values!
> 
> What has happened?! Id there something set up for
> backwards compatible pickup's?
> 
> steph

The pickup(s) have changed (see the tag-index), and no "clever" 
automatic way to restart from an old pickup are implemented.
(we are waiting for netcdf pickup files that will allow to 
 make this kind of transition transparent for the users).
So, you will have to add in the data file:
>  usePickupBeforeC54=.TRUE.,
(see for example, verification/global_ocean.cs32x15/input/data)
and to turn it off when you restart from a new pickup (= produced
by the new code).

This works, except for the pickup_ptracers that
have been produced with a version of the code
between checkpoint54a_pre and checkpoint54d_post.
(I recommand not to use such a version with ptracers, 
 or to tell me that it's a real problem and in this case
 I can create an other flag that will allow to restart
 from this kind of pickup_ptracers).

Thanks,

Jean-Michel