[MITgcm-support] data precision

[Renske Gelderloos]

Hi,

With the large number of questions in this discussion the question about
eta being 0 at open boundaries is still unanswered. As I've been
wondering about this myself I'm very curious about the reason behind it.
Could anyone explain please? Thanks.

Renske


名 徐 wrote:
> Hi Martin
> Thank you for your answer.It is unfortunate that I still couldn't open
> the web
> http://ecco2.jpl.nasa.gov/data1/arctic/run_template_cube81/mk_run_template.m
>
> What has happened,I don't know?Now,I have modified the routine
> "solve_for_pressure.F " to minus the sea level raise mean afer some
> calculate steps.But I couldn't confirm it is reasonable.
> In addition,the eta=0 on open boundary always,why?
> PS: My name write in Chinese not in English,so you can't transcribe.
>
>
>
>
>
>
>     Hi 名 徐,
>
>     (I still cannot transcribe your name (o:)
>
>     the readBinaryPrec flag pertains only to input data (such as bathymetry, inital
>     conditions, open boundary values, forcing fields, grid fields etc.) If you use
>     the pkg/exf, then those fields can be handled separately. Likewise
>     writeBinaryPrec controls the precision of the output fields that the model will
>     produce for you.
>
>     Regardless of these flags, all floats are defined and handled as real*8 (there
>     is a macro in the code "_RL" that expands to real*8 and one
>     "_RS" that also expands to real*8, unless you redefine it, but
>     that's not really recommended), and you cannot/must not/do not have any
>     sensible reason to change that. All *_R8/RL routines handle _RL variables and
>     all *_R4/RS handle _RS variables, but for most (nearly all) people _RL and _RS
>     are really the same (that is, real*8). So nothing to worry about.
>
>     Martin
>
>     PS. Thinking about your obcs balance problem, balancing the inflow offline will
>     be far more effective, if your input fields are real*8 (readBinaryPrec=64), in
>     fact I recommend doing it that way.
>
>     On 8 Jan 2009, at 05:40, 名 徐 wrote:
>
>     > Dear all
>     >      The default value of readBinaryPrec(writeBinaryPrec) is 32 in data
>     PARM01.Does it imply the input data  precision must be 32(single
>     precision,real*4).But many subroutines have been call on  the program read data
>     on double precision(64,real*8) ,such as global_sum_R8 in cg3d.F.Is it a bug?How
>     can I conform it!
>     > 
>     > Thanks
>     > 
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-- 


Ir. Renske Gelderloos
KNMI
P.O. Box 201
3730 AE De Bilt
The Netherlands
+31 30 2206361
gelderlo at knmi.nl