[MITgcm-support] ptracer/DIC budget closure/calendar pkg

[Hannah Kleppin]

Dear MITgcm-community,

I'm struggling closing an offline budget of some tracers (using package 
ptracer and a modified version of the DIC package). The residual between 
LHS (dTracer/dT, based on snapshots of Tracer) and the RHS (monthly 
averaged diffusive, advective and biological fluxes) is about an order 
of magnitude smaller than the actual tendency. I am using as well the 
package calendar to write output that corresponds to actual calendar 
month (calendarDumps = .TRUE. in data.cal). I realised now, that the 
calendar output is not implemented for ptracers and it seems also not to 
be effective for the snapshots of the state variables. This could 
possibly explain some offset in the budgets, since the advective, 
diffusive and biological flux output corresponds to the actual calendar 
month. For ptracer snapshot output I tried to implement the "Calndar 
dumps" in file ptracers_write_state.F by replacing lines 51-56 by


#ifdef ALLOW_MNC
dumpFiles=DIFFERENT_MULTIPLE(PTRACERS_dumpFreq,myTime,deltaTClock)

#ifdef ALLOW_CAL
       IF ( useCAL ) THEN
          CALL CAL_TIME2DUMP( zeroRL,PTRACERS_dumpFreq, deltaTClock,
      U                       dumpFiles,
      I                       myTime, myIter, myThid )
       ENDIF
#endif

       IF ((dumpFiles).OR.(dumpInitAndLast.AND.( myTime.EQ.endTime .OR.
      &                             myTime.EQ.startTime ))) THEN

This works except that I don't have output on the first time step (the 
simulation is still running, so I don't know about the last time step yet).

Has anyone a suggestion why I don't get output at the first time step?

Could  someone point me to where this would need to be implemented in 
order to write calendar snapshots of eta?

Shouldn't there be a warning in the calendar package documentation that 
it is not implemented for all packages? (I know "Always look at your 
meta data, ..." )

Other questions that are relevant for my budget calculations:

Is it true that there is no diagnostics available that contains the OBCS 
contribution to ptracers (RBCS contribution seems to be in the 
diagnostic ForcTr**)

Is the resetting of negative tracer values in DIC and Bling somehow tracked?

Any suggestions are greatly appreciated.

Cheers,

Hannah