[MITgcm-support] hfac question

[David Hebert]

Matt,

Along those lines, I notice in obcs_calc.F, for the balance routines, 
that hFacC's are used instead of hFacW for E/W boundary and hFacS for 
N/S boundaries. Could that also be related to the hFacW and hfacC 
assuming periodic BC/s?

Thanks,

David

On 10/06/09 11:09, Matthew Mazloff wrote:
> Hi David,
>
> It is a bit odd that it gave you 90 for hFacW(1,:), but I guess it is 
> fine as I believe what happens on the western open boundary is that it 
> sets U(1,:) and U(2,:) to the prescribed value and sets (assumes) zero 
> divergence right on the boundary center (helps pressure solver).  So 
> yes, I believe what is truly coming into the dynamics -- and what is 
> entering the domain -- is sum(U(2,:).*drF .* hfacW(2,:)).
>
> -Matt
>
>
> On Oct 6, 2009, at 8:56 AM, David Hebert wrote:
>
>> Hi Matt,
>>
>> The point I mentioned is a W boundary point (should  have noted that 
>> before, sorry). All surrounding points  are  also 100m. I do note 
>> that the Eastern boundary is 90m. So if hFacW will obtain depth on 
>> Eastern bounary is there something different I should do on the West? 
>> i.e., seems I should use hFacW(2,:)?
>>
>> Thanks
>>
>> David
>>
>> On 10/06/09 10:49, Matthew Mazloff wrote:
>>> Hi David,
>>>
>>> This is correct.  You must have sloping topography and the depth at 
>>> the west side of the cell is 90m, while its 100m in the center.  U 
>>> is calculated on the west face, so the total volume transport is
>>> sum(U(1,:).*drF .* hfacW(1,:)).
>>>
>>> Likewise one should use hFacS for V transport.
>>>
>>> -Matt
>>>
>>>
>>> On Oct 6, 2009, at 8:38 AM, David Hebert wrote:
>>>
>>>> Hi all,
>>>>
>>>> I am attempting to balance barotropic inflow/outflow on the 
>>>> boundaries of a 2D simulation. I ran the model one timestep to 
>>>> obtain the hFac's in order to more accurately determine the depth 
>>>> the model uses. The result from Depth.data at one point is 100m.
>>>>
>>>> In order to balance U, according to manual, I would use hFacW. I 
>>>> get a very different result if I do sum(drF * hFacW). Results from 
>>>> matlab (for 2D hFac's)...
>>>>
>>>> sum(drF .* hfacW(1,:)) = 90
>>>> sum(drF .* hfacC(1,:)) = 100
>>>>
>>>> Seems I don't quite understand hfacW. Any ideas on what I did wrong 
>>>> here?
>>>>
>>>> Thanks
>>>>
>>>> David
>>>>
>>>>
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