[MITgcm-support] exf interp

[Matthew Mazloff]

Hi Chris,

Yeah, its relatively easy to test.  I'll give it a try on monday and  
let you know

-Matt

Dimitris, what issues arose when using bicubic before for buoyancy  
terms -- anything specific I should look out for?

-Matt


On Oct 17, 2009, at 1:14 PM, Chris Hill wrote:

> Matt,
>
> I think the bicubic is worth trying. As I understand Benny's code it
> is meant to be c1 continuous
> which should help.
> My hope is that the bilinear temps are affecting the wind stress
> (because atemp/SST feature in static stability calcs in bulk formula
> and in turbulent mixing calcs and so affect momentum flux).
> Is it quick(ish) to run a test?
>
> If this doesn't work I have a couple of other things that would be
> kind of interesting to try. They involve doing stuff offline
> initially.
>
> Chris
>
> On Sat, Oct 17, 2009 at 1:36 PM, Matthew Mazloff <mmazloff at mit.edu>  
> wrote:
>> Hi Chris,
>>
>>> Are the surface data sets 1/2 degree res?
>>
>> 1 degree res -- starting at the half degree:
>> uwind_lon0         = 229.5D0,
>> uwind_lon_inc      = 1.D0,
>> uwind_lat0         = 26.5D0,
>> uwind_lat_inc      = 15*1.D0,
>>
>>> My guess is it is the piecewise constant in the aTemp/aQ/radiation?
>>
>> I'm confused, I'm plotting windstress curl, and the wind speed uses  
>> bicubic
>> interpolation already.
>> Do you think this is a feedback from buoyancy forcing be linearly
>> interploated?  I can check the wind speed to ensure the signal is  
>> not coming
>> from the (ocean) relative speed in the stress calculation.
>>
>>> If the spline is done right
>>> the overshoots should be small in a limited area domain, so you  
>>> could try
>>> that.
>>
>> You mean trying bicubic for buoyancy components?
>>
>>
>> Thanks for the help!
>> -Matt
>>
>>
>>
>>>
>>> Chris
>>>
>>> On Sat, Oct 17, 2009 at 11:38 AM, Matthew Mazloff <mmazloff at mit.edu>
>>> wrote:
>>>>
>>>> Hi Dimitris,
>>>>
>>>> See the lines at X.5 degrees.  Its not very noticeable in  
>>>> snapshots, but
>>>> really stands out in the mean as the signal is accumulated
>>>>
>>>> -Matt
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Oct 17, 2009, at 7:42 AM, Dimitris Menemenlis wrote:
>>>>
>>>>> Matt, could you send an example figure of problem?
>>>>>
>>>>> On Oct 17, 2009, at 7:29 AM, Matthew Mazloff wrote:
>>>>>
>>>>>> Hi Dimitris,
>>>>>>
>>>>>> Ah yes, I see this now.  Very nice.  Unfortunately the gridding  
>>>>>> is
>>>>>> still noticeable in my plots of wind speed gradient.  I am able  
>>>>>> to
>>>>>> pick out the exact locals where the forcing is prescribed --  
>>>>>> meaning
>>>>>> the interpolation is not smooth.  This is not good for plotting  
>>>>>> wind-
>>>>>> stress curl. Have you noticed this on your high-res set-ups?   
>>>>>> Do you
>>>>>> think this is a problem?  Should we (can we) try a smoother  
>>>>>> interp
>>>>>> method?
>>>>>>
>>>>>> -Matt
>>>>>>
>>>>>> On Oct 16, 2009, at 5:03 PM, Dimitris Menemenlis wrote:
>>>>>>
>>>>>>> Matt, I hardcoded bilinear interpolation for tracer fields  
>>>>>>> because
>>>>>>> overshoots can be problematic and bicubic for wind velocity (see
>>>>>>> exf_set_uv.F) for stress fields because the second derivative
>>>>>>> matters.  I would recommend to leave as is.  Other  
>>>>>>> combinations can
>>>>>>> (or did) cause trouble.  Dimitris
>>>>>>>
>>>>>>> On Oct 16, 2009, at 3:21 PM, Matthew Mazloff wrote:
>>>>>>>
>>>>>>>> Hello,
>>>>>>>>
>>>>>>>> It appears the model is equipped to do both bilinear and  
>>>>>>>> bicubic
>>>>>>>> interpolation for exf_interp.F.  Interp_method, however, is  
>>>>>>>> hardcoded
>>>>>>>> to bilinear interpolation.  This does matter for my 1/16  
>>>>>>>> degree set-
>>>>>>>> up.  Can anyone confirm that the bicubic interpolation is ok  
>>>>>>>> -- and I
>>>>>>>> can go ahead and use this option.
>>>>>>>>
>>>>>>>> -Thanks,
>>>>>>>> Matt
>>>>>
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