[MITgcm-support] exf interp

[Chris Hill]

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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