[MITgcm-support] 'repeatPeriod' in data.exf

[David Hebert]

Suneet,

I believe repeatPeriod is the period in which the model will go back to 
the beginning of the forcing file. So if you wish to use the same 
forcing for each year (one file with 366 days according to your last 
post), I don't see why you couldn't specify repeatPeriod=31622400.0 in 
data.exf. Also, you would need to specify the period between records in 
your file in data.exf, &EXF_NML_02. For your case if they are daily I 
would think it would be 86400.0. Example for wind stress would be...

&EXF_NML_02
  ustressfile        = 'taux.bin',
  vstressfile        = 'tauy.bin',
#
  ustressstartdate1   = 20080628,
  ustressstartdate2   = 000000,
  ustressperiod       = 3600.0,
#
  vstressstartdate1   = 20080628,
  vstressstartdate2   = 000000,
  vstressperiod       = 3600.0,
&

where ?stressperiod is the period between records. My case was one hour. 
Your case could be 86400.0 for one day.

A question that arises (for me anyway) is how to handle leap years, 
particularly with calendar package? Does assuming 366 days cover this?

David



On 06/22/10 08:22, Suneet Dwivedi wrote:
> Hi Martin,
>
> Thanks for your reply. Your suggestion is helpful. However, if i 
> follow what you suggested for 60 years of simulation, for example, 
> then for 8 air/sea forcing fields i will have to create 480 (60*8) 
> yearly forcing files, which is possible, but cumbersome. An 
> alternative that I could think of may be to run the model for somewhat 
> shorter duration and restart from there...., for example, running the 
> model for 15 years at a time and restart from there again for 15 years 
> and so on.....Thus rather than splitting forcing fields into years, 
> one may split time window.
>
> I guess in this case, i should set repeatPeriod = 0 in data.exf, if i 
> am using continuous in time daily forcing fields for 15 years. But I 
> am not sure how to set namelist parameters in input/data while 
> restarting from pickup files. What i could gather from looking at 
> verification directory examples and mitgcm manual is that it is 
> possible to restart the model from pickup files by setting nIter0 
> equal to number as suffix in pickup file, but i am not sure how to set 
> data.cal in this case. Probably, I should not include data.cal in my 
> input directory when I am restarting. Is this right? Any suggestions....
>
> Thanks again,
> Suneet
>
> On Tue, Jun 22, 2010 at 8:19 AM, Martin Losch <Martin.Losch at awi.de 
> <mailto:Martin.Losch at awi.de>> wrote:
>
>     Suneet,
>
>     you can split you forcing fields into years. They have to follow
>     this naming convention:
>     forcingFile_year, where "year" is a 2 or 4-digit year (e.g.
>     myatemp_1996, myatemp_1997, etc).
>
>     In data.exf set:
>      useExfYearlyFields= .TRUE.,
>      twoDigitYear      = .FALSE.,
>
>     and
>     atempfile = myatemp,
>     etc. If you want to use a Gregorian calendar the data.cal should
>     look like this:
>     &CAL_NML
>      TheCalendar='gregorian',
>     # here you insert your start date, of course
>      startDate_1=19920101,
>      startDate_2=000000,
>     # this makes the model interpret output "freqs" (e.g. dumpFreq)
>     close to 1 month (say 2592000.) as a "real" month, the same for a
>     year.
>      calendarDumps = .TRUE.,
>     &
>
>     There are a few examples in the MITgcm_contrib area (arctic,
>     high_res_cube)
>
>     Martin
>
>
>     On Jun 22, 2010, at 1:38 AM, Suneet Dwivedi wrote:
>
>     > Hi Everybody,
>     >
>     > Could anyone of you please tell me what is the exact meaning of
>     parameter 'repeatPeriod' in exf package/data.exf?
>     >
>     > I wish to perform a long run of 50-55 years with daily air/sea
>     forcing values over Indian Ocean. Matlab is unable to store and
>     process such a long matrix of dimension [250 150 20000] ~ O(1e+10)
>     with 64 bit precision. An alternative way to do this may be to use
>     climatological daily forcing values (averaged over all available
>     years) of dimension [250 150 366] and use the climatological
>     values for each year of simulation. In this case, i need to know
>     the variable that does this in MITgcm. I wonder 'repeatPeriod'
>     does this. Am I right? For example, if i set 'repeatPeriod' to
>     something like 31622400.0 (for 1 year), will I be able to use same
>     values of forcing on same days of each year after completing one
>     year of simulation? Please suggest.
>     >
>     > Thanks,
>     > Suneet
>     >
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