[MITgcm-support] filters for vertical velocity in cubed-sphere grid

[Yuan Lian]

Hi Andrea,

Thanks for your help. I tried several parameter configurations in "data" 
and it seems working a
little better now at grids corners. I have contacted with Jean-Michel 
but he hasn't come back yet.
I may be visiting MIT by the end of July and we can discuss the problem 
in details by then.

Cheers,
Yuan

Andrea Molod wrote:
> hi yuan,
>
>> I noticed Shapiro filter is not applied to vertical velocity 
>> (atmospheric model, maybe generally for oceanic model as well).
>> Ideally, the vertical velocity should be calculated from continuity 
>> equation. However, corner effect on vertical velocity are
>> noticeable, ie, stronger upward or downward motions comparing to 
>> elsewhere. In a neutrally stable atmosphere, air at corners
>> will experience adiabatic heating or cooling and cause local maximum 
>> (or minimum) of temperature.
>
> can you tell me which setup/experiment etc... you are using? i ask
> because there are a set of grid files for the 32x32 cube that were put
> together by jean-michel to address this issue. indeed, the vertical
> velocity at the corners under certain circumstances got noisy, and
> he made some adjustments to the locations of the grid cell edges
> relative to the centers (if i have this correct...) that made most
> of this go away. you can find them in the directory: 
> verification/fizhi-cs-32x32x40/input and they are called dxC1....
>
> as far as i understand things, trying to put the vertical velocity
> through the shapiro filter would not 'really' address the problem,
> it would sort of mask it and maybe even make a bigger mess.
>
>>
>> Also, it there any way to generate high resolution cubed-sphere grid 
>> while maintaining the ratio of grid areas?
>>
>
> again, as dimitris asked, what do you mean by 'high res'?
> (the link he gave you is for the 'really' high res - i have generated
> a new cubed sphere grid FROM the one he talked about with just under 1 
> degree resolution). also - as far as i know, any of the cubed sphere
> grids that people here have generated try to maintain the good ratio 
> of grid areas.....
>
> hope some of this answers your questions.
>
> andrea
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