[MITgcm-devel] ptracers

[Chris Hill]

You're right anything is possible! But I would try 3 first.

> -----Original Message-----
> From: mitgcm-devel-bounces at mitgcm.org 
> [mailto:mitgcm-devel-bounces at mitgcm.org] On Behalf Of Patrick Heimbach
> Sent: Thursday, October 23, 2003 11:27 PM
> To: MITgcm-devel at mitgcm.org
> Subject: Re: [MITgcm-devel] ptracers
> 
> 
> 1 and 2 may mess up the flow dependencies though,
> depending on how TAF does them.
> I'll try it incrementally.
> -p.
> 
> Chris Hill wrote:
> > That's great. Lets hope that 3 fixes it.
> > 
> > 1 and 2 will be tidied up. Its very unlikely they could 
> ever cause a 
> > problem as is because all references within the routines and lower 
> > down in the call trees are only to the dummy args and there are no 
> > refs to the common members. However, it is messy and unecessary to 
> > have the global refs visible so it should be cleaned up.
> > 
> > Chris
> > 
> > 
> >>-----Original Message-----
> >>From: mitgcm-devel-bounces at mitgcm.org
> >>[mailto:mitgcm-devel-bounces at mitgcm.org] On Behalf Of 
> Patrick Heimbach
> >>Sent: Thursday, October 23, 2003 10:51 PM
> >>To: MITgcm-devel at mitgcm.org
> >>Subject: [MITgcm-devel] ptracers
> >>
> >>
> >>Hi there,
> >>
> >>I'm copying this message from Ralf.
> >>He was looking into why the derivative code
> >>of ptracers gave wrong gradient checks.
> >>
> >>I'll hopefully check in the modif's tomorrow
> >>together with AD-related modif.s for genmake2.
> >>
> >>We need to discuss point 2.
> >>
> >>-Patrick
> >>
> >>--------------------------------------------------
> >>
> >>Hi,
> >>
> >>I have worked on the problem in the ptracer adjoint.
> >>Thereby I found three problematic things in the code.
> >>The third one causes the adjoint to be wrong.
> >>
> >>Please find enclosed my changes to the code which fixes 1)
> >>and 3) but not 2).
> >>
> >>Ralf
> >>
> >>
> >>1) Aliasing problem in ptracers_forcing.F
> >>
> >>C !INTERFACE:
> >>==========================================================
> >>       SUBROUTINE PTRACERS_FORCING(
> >>      I                            bi,bj,k,iTracer,
> >>      U                            gPtracer,
> >>      I                            myIter,myTime,myThid )
> >>
> >>C !DESCRIPTION:
> >>C     Adds sources and sinks of passive tracers to the 
> tendancy arrays
> >>
> >>C !USES:
> >>===============================================================
> >>       IMPLICIT NONE
> >>#include "SIZE.h"
> >>#include "EEPARAMS.h"
> >>#include "PTRACERS.h"
> >>#include "PARAMS.h"
> >>#include "FFIELDS.h"
> >>#include "GRID.h"
> >>
> >>It is not necessary to include PTRACERS.h and it even
> >>violates the Fortran standard. Thats because the variable 
> >>gPtr is passed as argument and becomes dummy argument 
> >>gPtracer. Now there are local arrays gPtr and gPtracer being 
> >>the same array! This aliasing is not allowed if one of them 
> >>is modified, which is the case here.
> >>Fix: just remove #include PTRACERS.h  .
> >>
> >>
> >>2) Similar in GAD_CALC_RHS, gTracer is dummy argument and is
> >>aliased to gS by the call in calc_gs and aliased to gT by the 
> >>call in calc_gt. But here
> >>   #include "DYNVARS.h"
> >>cannot be removed since the arrays UVEL, VVEL, and WVEL are needed.
> >>Fix: not as simple, split DYNVARS.h, pass UVEL, VVEL, and 
> >>WVEL, or use tracerIdentity to identify which array is to be 
> >>used instead of dummy argument ptracer.
> >>
> >>
> >>3) In ptracers_integrate.F there is a local array rFlx which
> >>is only initialized for k.EQ.Nr . My guess it that it is 
> >>updated for all k.lt.Nr . But in this case it must either be 
> >>saved or declared in thermodynamics and passed as argument to 
> >>ptracers_integrate (similar to fVerS in thermodynamics) 
> >>otherwise its not initialised and used if not k.EQ.Nr !
> >>
> >>C  rFlx			:: vertical flux
> >>       INTEGER i,j,iTracer
> >>       INTEGER iMin,iMax,jMin,jMax
> >>       INTEGER kUp,kDown,km1
> >>       _RL rFlx(1-OLx:sNx+OLx,1-OLy:sNy+OLy,2,PTRACERS_num)
> >>       LOGICAL calcAdvection
> >>CEOP
> >>
> >>C Loop over tracers
> >>       DO iTracer=1,PTRACERS_numInUse
> >>
> >>C Initialize vertical flux to zero and set no-flux across k=Nr+1
> >>        IF (k.EQ.Nr) THEN
> >>         DO j=1-Oly,sNy+Oly
> >>          DO i=1-Olx,sNx+Olx
> >>           rFlx(i,j,1,iTracer)=0.
> >>           rFlx(i,j,2,iTracer)=0.
> >>          ENDDO
> >>         ENDDO
> >>        ENDIF
> >>
> >>
> >>--
> >>###################################################
> >>Dr. Ralf Giering
> >>NEW ADDRESS:
> >>FastOpt, Schanzenstr. 36, 20357 Hamburg, Germany
> >>Tel.: +49 40 48096347
> >>Fax : +49 40 48096357
> >>Email: Ralf.Giering at FastOpt.de
> >>URL : http://www.FastOpt.de 
> >>###################################################
> >>
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> >>
> > 
> > 
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> 
> -- 
> Patrick Heimbach ........................... M.I.T
> FON: +1/617/253-5259 .......... EAPS, Room 54-1518
> FAX: +1/617/253-4464 ..... 77 Massachusetts Avenue 
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