[MITgcm-support] generate a stable current field

[Jody Klymak]

Hi Pu,

I set these times in “data”:

periodicExternalForcing=.TRUE.,
externForcingPeriod=1860.,
externForcingCycle=44640.,

(this has 24 equally spaced forcings).  So, you need to specify these in your file.  However, note that it is periodic in “externForcingCylce” so if you want a ramp to a steady forcing in time, you want to make sure this value is quite large, and you will have to set a relatively large number of fields in your external forcing function.  

I think if you don’t set these, the default is “0” which means the OBWuFile is read as being a constant boundary condition (i.e. just the first 1*NR values are read).  

> On 6 Jul 2015, at  11:37 AM, Matthew Mazloff <mmazloff at ucsd.edu> wrote:
> 
> Unfortunately there is no verification experiment exactly like what you want, but these may help:

Hmm, yes, verification/internal_wave could be re-done to force the boundary using obcs or rbcs instead of hardcoding, which is what it does now.  If I have some spare time I’ll submit a modification to the devs.

Cheers,  Jody



> verification/obcs_ctrl
> verification/seaice_obcs
> 
> Matt
> 
> 
> On Jul 5, 2015, at 2:13 PM, <guopu at scsio.ac.cn <mailto:guopu at scsio.ac.cn>> wrote:
> 
>> Hello Sir,
>> 
>> I feel the OBCS package is so complicate, so I start from generating a simple current field to understand this package. Now I have 3 questions:
>> 
>> 1. I build a 2D region with uniform depth 1000m, and set OB_Iwest=1, OB_Ieast=-1. Now I am wondering how to generate a stable barotropic current in this region. The only effective way I found is to use files containing uniform velocity for parameters: "uVelInitFile", "OBWuFile", and "OBEuFile". Is it right? or is there another "standard procedure" ?
>> 
>> 2. I want to generate above current field by only one prescribe file for "OBWuFile", so I make this (1*Nr*50)-dimension file with gradually increased velocity, from 0 (or 0.01) to 0.1m/s in 50 "time levels". However, the model results show that U at west boundary keep to be zero (or 0.01m/s). What could be the reason for this? and what is the meaning of "time levels"?
>> 
>> 3. I add a Gaussian shape obstacle on the bottom and hope to see what will happen in this region. Should I turn on one or some of these flags: useOBCSsponge, useOrlanskiEast/West, useOBCS_balance? I thought the "OB_Iwest=1, OB_Ieast=-1" would be enough to let water/waves flow/propagate out freely.
>> 
>> Studying this package has cost me several weeks, I am hungry for help, thanks!
>> 
>> Pu
>> 
>> 
>> 
>> 
>> 
>> 
>> 
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--
Jody Klymak    
http://web.uvic.ca/~jklymak/





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