[MITgcm-support] Bulk Force and SSS restoring

Wed Feb 17 14:28:29 EST 2010

Amato,
to be honest, I have not fully understand the problem, but that aside:

I meant "global_with_exf/input.yearly" (I was not aware that there are two sub-input directories in this experiments), so theCalendar="model", is an option and implies 12 30-day-months

Now for your problem: As far as I can tell you use the "external_fields_load"-method to load the forcing, right? (with these filenames:
     & zonalWindFile, meridWindFile,
     & thetaClimFile, saltClimFile,
     & surfQnetFile, surfQswFile, EmPmRfile
in data, PARM05) for your spin-up. Your qnet = qsw(net) + lw(net) + qsh + qlh. lw(net) = lwup - lwdown, where qlwup=emissivity*boltzmann*SST^4 or so. Now, if you want to change your long wave downward radiation, why not compute qnet-lwdown + new_lwdown. The lwdown is part of the NCEP fields (at least the variant that I once downloaded from the LDEO ingrid server (http://iridl.ldeo.columbia.edu/, specifically: <http://iridl.ldeo.columbia.edu/SOURCES/.NOAA/.NCEP/.EMC/.CMB/.T40/>) and that is the basis of most of my climatological simulations without sea-ice.

In exf, you can specify wind (or stress), lwdown, swdown, humidity, surface air temperature, precipitation (and with an additional flag, also evaporation), or net lwflux and net swflux (depends on the CPP-flags, see EXF_OPTIONS.h for more details).

Martin

On Feb 17, 2010, at 5:07 PM, Amato Evan wrote:

> Hi Martin,
> 
> Thanks a lot for chiming in here!
> 
>> in data.cal you can specify the 'model calendar' (see global_with_exf for an example), so that should not stop you from use exf instead of bulk_force. Although my experience with bulk_force is very limited, the exf does have quite a few options, and I think it should do what you need.
> I would certainly much rather use EXF. global_with_exf has "TheCalendar='gregorian'". I did incorporate cal and exf into my current model setup, but I could not get the model to run if I had "TheCalendar='model'" (it did work w/gregorian though). And then I saw something on the mailing list where someone said that with EXF you have to use the gregorian calendar. Then I stopped playing with EXF since I don't want to deal w/leap years!
> 
>> Did you have a look at global_ocean.cs32x15/input.thsice/ for an example use of bulk_force?
> I did, I can get BULK_FORCE going in my model setup, I'm just trying to determine if I can use it w/o the model calculating freshwater fluxes from a rain or runoff file (only SSS restoring), which I couldn't deduce from the code/documentation. Not such a huge thing if not I suppose. I'm just trying to save myself some time.
> 
> Sincerely,
> Amato
> 
> 
> 
>> 
>> Martin
>> On Feb 17, 2010, at 3:58 PM, Amato Evan wrote:
>> 
>>> Hi Stefano!
>>> 
>>> I was hoping to use the model calendar (just b/c it's more straightforward) and as far as I can tell, if one uses EXF then calendar has to be set to "Gregorian". Is this right?
>>> 
>>> I should say that another reason for only restoring to SSS is that this is how I have spun up the model, so I'd like to stay consistent on this front as well.
>>> 
>>> Thanks for your time, I really appreciate it!
>>> 
>>> Sincerely,
>>> Amato
>>> 
>>> On Feb 17, 2010, at 4:37 AM, Stefano Querin wrote:
>>> 
>>>> Hi Amato,
>>>> 
>>>> just a few ideas...
>>>> 
>>>> Have you ever tried to use the EXF package for your simulations? It
>>>> should be more complete and flexible than the BULK_FORCE package. You
>>>> can also restore SSS to prescribed values with it.
>>>> 
>>>> I don't think that the computation of freshwater fluxes using runoff
>>>> and precipitation input files makes the model run that slow... (but
>>>> I'm just relying on my experience, I never made any test regarding
>>>> this). On the contrary, if you meant that the creation and handling
>>>> (offline) of runoff and precip files is somehow cumbersome and slow,
>>>> then SSS restoring should be a more desirable choice.
>>>> 
>>>> Anyway, the EXF package has many available options.
>>>> 
>>>> Hope this helps...
>>>> 
>>>> Cheers!
>>>> 
>>>> S.
>>>> 
>>>> 
>>>> 
>>>> On 16 Feb 2010, at 19:50:23, Amato Evan wrote:
>>>> 
>>>>> Hello Everyone,
>>>>> 
>>>>> I am trying to estimate the effect of surface forcing by volcanic-
>>>>> aerosols on tropical SST. To do this I have a 1x1 degree model setup
>>>>> w/23 vertical levels. After spining up the model for 130 years using
>>>>> NCEP and WOA data (and SSS restoring), I would like to "turn-on" the
>>>>> BULK_FORCE package in order to change downward lw & sw fluxes in
>>>>> accordance with volcanic aerosol surface forcing (something I
>>>>> calculate offline w/satellite obs. and an RT model).
>>>>> 
>>>>> I am giving the BULK_FORCE pkg wind stress values (calcWindStress
>>>>> = .FALSE.), but I would like to run w/surface salinity restoring,
>>>>> and not have the model calculate freshwater fluxes using runoff and
>>>>> precip input files. My motivation is just to make the model runs
>>>>> complete more quickly. What I can't determine from the documentation
>>>>> and source code is if I leave:
>>>>> 
>>>>> RainFile= ' ',
>>>>> RunoffFile= ' ',
>>>>> EmPFile= ' ',
>>>>> 
>>>>> in data.blk, will bulk_force just restore to surface salinity on the
>>>>> time scales I define in "data"? If anyone has experience with this,
>>>>> I would really appreciate input. Also, the contents of build/,
>>>>> code/, and input/ for my setup can be found here:
>>>>> 
>>>>> http://trane.evsc.virginia.edu/mitgcm/
>>>>> 
>>>>> If anyone is so inclined to look them over.
>>>>> 
>>>>> Thanks!
>>>>> 
>>>>> Sincerely,
>>>>> Amato
> 
> ---
> Amato Evan
> Asst. Professor
> Dept. of Environmental Sciences
> University of Virginia
> 434.243.7711
> aevan at virginia.edu
> http://trane.evsc.virginia.edu
> 
> 
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