[MITgcm-devel] exf: u/v-wind interpolation and cubed sphere

[Dimitris Menemenlis]

Martin, as discussed, I have just checked-in a cleaner way to deal with North 
Pole for exf interpolation and rotation routines.  It is not as robust as your 
suggestion, i.e., if lat/long forcing fields are crap near the pole, so will the 
  resulting interpolated fields, and it does not conserve anything in particular 
as Ed's upcoming version will, but it is simple and cheap and therefore worth a 
try.  Specifically, there are three options:

1) For tracer forcing fields, interpolation is carried out by setting 90N to the 
mean value of the forcing field at its northernmost latitude.  This avoids 
"ripples" as the North Pole is approached.

2) For zonal vector fields, interpolation is carried out by setting 90N to zero. 
  This smooths out strength of Polar vortex at the North Pole, hence removing 
the discontinuity noted in Martin's last message.

3) For meridional vector fields, interpolation is carried out as before, that 
is, 90N for each longitude grid is set to corresponding value at northernmost 
latitude.  This is supposed to allow for cross-pole flow, if any.

Dimitris