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

[Suneet Dwivedi]

Hi David,

Thanks for your reply. This is exactly what i had in mind for
'repeatPeriod'.

Though I am not very sure about your last question, I think a forcing file
with 366 days will take care of both leap years (of 366 days) and normal
years (of 365 days). But a file with lesser number of days (for example 365
days) will give an error for a leap year (no data on 31st Dec, in this
case).

Thanks,
Suneet

On Tue, Jun 22, 2010 at 3:45 PM, David Hebert
<david.hebert at nrlssc.navy.mil>wrote:

>  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> 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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