[MITgcm-support] Velocity cubed sphere + pickup seaice

[Martin Losch]

Hi Elja,

in addition, the orientation of u and v-velocity is along grid  
coordinates, which will give you funny results, if you try to plot  
them on some sort of map-projection. After interpolating, you need to  
rotate the velocities according to the values of angleCosC and  
angleSinC. Unfortunately, these fields are often not set, because the  
model does not need them for hydrostatic integrations (so that they  
are 1 and 0). There is a matlab script to compute the angles in  
<utils/matlab/cs_grid/cubeCalcAngle.m>

I am also attaching a matlab function that does the interpolation and  
takes care of the edges (for me, so I am not sure that this will work  
for you or anyone else, too).

Martin
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On 3 Jun 2008, at 16:00, Dimitris Menemenlis wrote:

>> Is there a matlab script available to calculate the total velocity  
>> field from the zonal and meridional velocity components on a cubed  
>> sphere? I know the quiver-command, but I am not sure that this  
>> option gives the correct results on the cubed sphere.
>
> velocity is output on c-grid: west face for u and south face for v,  
> so quiver will not be exactly correct.  are you trying to compute  
> sqrt(u^2+v^2)?  the best way to proceed is to interpolate to tracer  
> points before doing this computation, i.e., (u(i,j)+u(i+1,j))/2 and  
> (v(i,j)+v(i,j+1))/2
>
>> Secondly, I am using the saeaice package. If I want to do a  
>> restart, I change nIter0 (in data) to the required value. Then,  
>> the standard pick-up files are read. Do I have to take an  
>> additional step to pick up the pickup_seaice files, too?
>
> when you change nitero0 in data, the correct pickup_seaice files  
> will be used if useSeaice is .TRUE.
> No additional step is required.
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