[MITgcm-devel] code changes

[Martin Losch]

Hi Holly (and Patrick),

maybe better to continue this on the devel-list. 

I had another look into the ctrl-pkg. Your code below is basically a modified copy from ctrl_get_gen.F, right? This in turn looks similar to exf_set_gen.F except that there the -12 is implemented and the 0 is dealt with in exf_getffieldrec.F. In the current code I have copied the handling of fldperiod=0 from exf_getffieldrec to ctrl_get_gen_rec and this will have no effect on the surface forcing ctrl fields because in ctrl_get_gen 0 is interpreted as monthly values and ctrl_get_gen_rec is not called.

I suggest to change this behavior like this:
1. in ctrl_get_gen replace (xx_genperiod .EQ. 0) with (xx_genperiod .EQ. -12) to be consistent with exf_set_gen. This might affect a few set-ups and we have to be careful to communicate this change (how would we do this? support list?). The alternative is to use a different number for constant fields, e.g. -1, but that would be inconsistent with exf
2. add your code to ctrl_getobcs?.F but also replace 0 by -12

The second point is independent of the first one, but I find it strange to have different parameters behave differently (e.g., xx_obcswperiod and xx_atempperiod). 

In both cases ctrl_init.F also needs to be modified (the change from fldperiod 0 -> -12, and still catching the 0), so
>         if ( xx_atempperiod .EQ. 0 ) then
>         startrec=1
>         endrec=12
>         else
has to become
>         if ( xx_atempperiod .EQ. -12 ) then
>         startrec=1
>         endrec=12
>         elseif ( xx_atempperiod .EQ. 0 ) then

>         startrec=1
>         endrec=1
>         else
or so. But this is exactly the part of the ctrl-package, where I quickly loose the overview and I need Patrick's opinion.

Martin



On Mar 9, 2011, at 8:32 PM, Holly Dail wrote:

> [...] thought I'd ask a separate question re. your changes.
> 
> For ctrl period = 0, your changes in ctrl_get_gen_rec.F assume that a period = 0 indicates a single mean control field right?  For atmospheric controls, I believe the rest of the code is all set up to assume a period = 0 implies repeated monthly controls (see ctrl_get_gen.F for an example).  I have used the code this way for a long time for my atmospheric controls and it seems to work great for me.  Of course, for parity with exf it should really be that period = -12 maps to repeated monthly controls, in which case period = 0 mapping to a mean control field would be a perfect idea.  I would use both repeated monthly controls and annual mean controls regularly if available.
> 
> For OBCS controls, the current code base (before your changes) doesn't do repeated monthly controls if one sets period = 0.  I have a very simple fix for the 4 ctrl_getobcs?.F files tested if you want to check it in (I've only tested the ctrl_getobcss.F).  I'll append it below ... this code snippet replaces the single call to ctrl_get_gen_rec that is in these S/R now.  Of course this will probably only work properly if you decide to reverse your changes in ctrl_get_gen_rec.F (or to change it all to -12 for repeated controls).
> 
> Thanks -
> Holly
> 
> 
> # ifdef ALLOW_CAL
>         if ( xx_obcssperiod .EQ. 0 ) then
> c     record numbers are assumed 1 to 12 corresponding to
> c     Jan. through Dec.
>            call cal_GetMonthsRec(
>     O           obcssfac, obcssfirst, obcsschanged,
>     O           obcsscount0, obcsscount1,
>     I           mytime, myiter, mythid
>     &           )
>         else
> c--   Get the counters, flags, and the interpolation factor.
>      call ctrl_get_gen_rec(
>     I                   xx_obcssstartdate, xx_obcssperiod,
>     O                   obcssfac, obcssfirst, obcsschanged,
>     O                   obcsscount0,obcsscount1,
>     I                   mytime, myiter, mythid )
>        endif
> # else
> c--   Get the counters, flags, and the interpolation factor.
>      call ctrl_get_gen_rec(
>     I                   xx_obcssstartdate, xx_obcssperiod,
>     O                   obcssfac, obcssfirst, obcsschanged,
>     O                   obcsscount0,obcsscount1,
>     I                   mytime, myiter, mythid )
> # endif