[MITgcm-support] exf interp for smooth wind stress curl

[Matthew Mazloff]

Hi Dimitris,

I'm actually not the person who made the figure, and it is possible  
that the artifact is from something besides interpolation.   Though  
the lines where coincident with the NCEP grid.  Anyway, we solved the  
issue by switching to the higher resolution NAM winds, which we feel  
are a slightly better product anyway for our California region.

Time permitting I will return to this problem though, and double check  
the curl.

Thanks
Matt






On May 18, 2011, at 8:36 AM, Menemenlis, Dimitris (3248) wrote:

> Chris, thank you for getting back.
>
> Embarrassingly, our atmospheric grid edge effects appear to have  
> been artifacts of sloppy curl computation.  After repeating the  
> computation in a way consistent with model grid, the edge effects  
> went away.
>
> Matt, I wonder whether the wind stress curl artifacts in your CASE  
> (1/16^o) setup could originate from some other cause than the  
> exf_interp bicubic interpolation?
>
> For support list reference I attach the curl recipe that we used:
>
> Wind stress curl at  [ XG(i,j), YG(i,j) ] = dV/dx - dU/dy
> U(i,j) = EXFtaux(i,j)
> V(i,j) = EXFtauy(i,j)
> dV/dx = [ V(i,j) - V(i-1,j) ] / dxV(i,j)
> dU/dy = [ U(i,j) - U(i,j-1) ] / dyU(i,j)
>
> On May 18, 2011, at 7:55 AM, Chris Hill wrote:
>
>> Last I recall J-M and I were waiting to see Matt's code - since the
>> edges he had did not look entirely consistent
>> with interpolation error.
>>
>> Chris
>>
>> On Wed, May 18, 2011 at 1:20 AM, Matthew Mazloff  
>> <mmazloff at ucsd.edu> wrote:
>>> nope -- never tried Chris' superduper fix -- or maybe he has a  
>>> higher
>>> resolution atmospheric reanalysis hidden in the closet?
>>>
>>> -Matt
>>>
>>>
>>> On May 17, 2011, at 4:45 PM, Menemenlis, Dimitris (3248) wrote:
>>>
>>>> Yes, we have artifacts at edges of atmospheric forcing grid.
>>>>
>>>> So Chris never got back to you with his superduper offline fix  
>>>> for this
>>>> problem?
>>>>
>>>> Dimitris Menemenlis
>>>>
>>>> On May 17, 2011, at 3:58 PM, Matthew Mazloff wrote:
>>>>
>>>>> Hi Dimitris,
>>>>>
>>>>> I do use  bicubic interpolation on all NCEP fields -- but I  
>>>>> still have
>>>>> some artifacts in my wind stress curl for my CASE (1/16^o)  
>>>>> setup.  Is
>>>>> this what you are finding?
>>>>>
>>>>> -Matt
>>>>>
>>>>> On May 17, 2011, at 3:24 PM, Menemenlis, Dimitris (3248) wrote:
>>>>>
>>>>>> Chris and Matt, did issue below regarding bicubic exf_interp ever
>>>>>> get resolved?
>>>>>>
>>>>>> Is there a way to get smooth wind stress curl for hi-res
>>>>>> integrations from coarse-res atmospheric forcing?
>>>>>>
>>>>>> Dimitris
>>>>>>
>>>>>> http://mitgcm.org/pipermail/mitgcm-support/2009-October/006305.html
>>>>>>
>>>>>>> Hi matt
>>>>>>>
>>>>>>> can you put your wind fields, grid etc... Somewhere @ MIT. I  
>>>>>>> have
>>>>>>> code
>>>>>>> to fix this offline, but have never found a real setup where it
>>>>>>> mattered!
>>>>>>>
>>>>>>> Chris
>
>
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