[MITgcm-support] Re:How to reduce a reflection wave from OBCs!

[Pat Gallacher]

Hi,

I have been forcing the MITgcm model with barotropic tides and I'm 
having problems with the baroclinc internal waves reflecting from the 
boundaries. I'd appreciate a copy of your solution.

Thanks much,
Pat

------------------------------------------------------
Patrick C. Gallacher, PhD    gallacher at nrlssc.navy.mil
Oceanographer    Nonhydrostatic Coastal Ocean Modeling
Naval Research Laboratory        Phone: (228) 688-5315
Code 7331                    Secretary: (228) 688-4733
Stennis Space Center, MS 39529     FAX: (228) 688-5997
------------------------------------------------------



Jennifer MacKinnon wrote:

> Hi,
>
> I've been struggling with similar issues regarding internal waves and 
> boundary conditions.  My solution so far is to clamp the barotropic 
> velocities to be whatever you like (a simple sinusoid in your case), 
> but allow baroclinic velocities as well as T and S to radiate 
> internal-waves out of the domain using the Orlanski radiation option.  
> This requires a little bit of monkeying with orlanski_west.F and 
> orlanski_east.F, but is fairly straightforward.  Let me know if you'd 
> like a copy of my modified files. 
>
> Cheers,
>
> Jen 
>
> ---------------------------------------------------------------
> Dr. Jennifer MacKinnon
> Physical Oceanography Research Division
> Scripps Institution of Oceanography
> http://www-pord.ucsd.edu/~jen/ <http://www-pord.ucsd.edu/%7Ejen/>
> 858-822-3716
>
>
>>
>> *From: *Van Thinh Nguyen <vtnguyen at moisie.math.uwaterloo.ca 
>> <mailto:vtnguyen at moisie.math.uwaterloo.ca>>
>> *Date: *February 10, 2006 12:25:54 PM PST
>> *To: *mitgcm-support at mitgcm.org <mailto:mitgcm-support at mitgcm.org>
>> *Subject: **[MITgcm-support] How to reduce a reflection wave from OBCs!*
>> *Reply-To: *mitgcm-support at mitgcm.org <mailto:mitgcm-support at mitgcm.org>
>>
>>
>> Dear all,
>>
>> I would like to simulate internal waves generated by tidal forcing 
>> over a depression bump in a open channel (opened at east & west). My 
>> case is similar to exp4, but it's limited in 2D. The tidal current is 
>> from the East to West with u=Uo*sin(omega*t). At west and east OBCs I 
>> set:
>>
>> OBWu=Uo*sin(omega*t)
>> OBWv=0.
>> OBWt=tRef
>> OBWs=sRef
>>
>> OBWw=0. for nonhydrostatic
>> OBWeta=Eta=0.
>>
>> At Eastern OBC is set the same above.
>>
>> I extended the length of domain from 60km, 120km, ...
>> the depth of domain H=80m (shallow), depth of bump=50%*H.
>>
>> I got refection waves from both OBCs, because Temperature profile 
>> (linearized in depth) is fixed at these OBCs (always =tRef), however 
>> the temperature profile in inner domain has changed.
>>
>> Anyone may have an idea to help me to fix this problem?
>>
>> Thanks so much for your helps,
>>
>> Van Thinh
>>
>>
>> *From: *Dmitri Leonov <dleonov at ocean.washington.edu 
>> <mailto:dleonov at ocean.washington.edu>>
>> *Date: *February 10, 2006 12:51:35 PM PST
>> *To: *mitgcm-support at mitgcm.org <mailto:mitgcm-support at mitgcm.org>
>> *Subject: **Re: [MITgcm-support] How to reduce a reflection wave from 
>> OBCs!*
>> *Reply-To: *mitgcm-support at mitgcm.org <mailto:mitgcm-support at mitgcm.org>
>>
>>
>> Hello Van Thinh,
>>
>> I've used sponge boundary conditions for a similar problem. My 
>> data.obcs file looks like this
>>
>> &OBCS_PARM01
>> OB_Iwest=1,
>> OB_Ieast=-1,
>> useOBCSsponge=.TRUE.,
>> &
>>
>> &OBCS_PARM03
>> spongeThickness=10,
>> # inverse relax. coef's (seconds)
>> Urelaxobcsinner = 0.0,
>> Urelaxobcsbound = 32.0,
>> Vrelaxobcsinner = 0.0,
>> Vrelaxobcsbound = 32.0,
>> &
>>
>> You may want to try it.
>>
>> Dmitri
>>
>>
>
>
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