RDA datasets with staggered grids

[JohnLCaron]

datasets have wind, momentum fields on grid egdes, other fields on grid centers. handled correctly, but separate groups are created. would be nice to understand the notion of "stagger".

ds093.1 ds277.6/monthly

Grib1Gds{ template=0, nx=360, ny=418, scanMode=64, resolution=128, lastOctet=28, nptsInLine=null}
LatLon{ la1=-74.5, lo1=0.5, la2=64.499, lo2=359.50003, deltaLon=1.0, deltaLat=0.33333093}

Grib1Gds{ template=0, nx=360, ny=418, scanMode=64, resolution=128, lastOctet=28, nptsInLine=null}
LatLon{ la1=-74.0, lo1=1.0, la2=64.999, lo2=360.00003, deltaLon=1.0, deltaLat=0.33333093}

[JohnLCaron]

perhaps just combine groups, with annotation on the coords?

then teach CoverageCoordSys to deal with them

[JohnLCaron]

ds093.1 may not be a stagger, but y value is displaced 1/4 degree. The 720x361 grid is for atmospheric data and the 720x360 grid is for ocean data. maybe thats just the way it is, ie nothing to be done.

has 15M records on this grid, with 361 lats, start 90 end -90

Group LatLon_361X720-0p2500S-180p0000E (-1064064779) type=TwoD
 hcs = GdsHorizCoordSys
 name='LatLon'
  template=0
  gdsNumberPoints=259920
  scanMode=0
  proj=LatLonProjection
  startx=0.0
  dx=0.5
  starty=90.0
  dy=-0.5
  nx=720
  ny=361

and 3.5 m records with 360 points, start = 89.75 end -89.75

group LatLon_360X720-0p2500S-179p7500W (-1063452200) type=TwoD
 nfiles 0
 hcs = GdsHorizCoordSys
 name='LatLon'
  template=0
  gdsNumberPoints=259200
  scanMode=0
  proj=LatLonProjection
  startx=0.25
  dx=0.5
  starty=89.75
  dy=-0.5
  nx=720
  ny=360

[JohnLCaron]

From Bob Dattore:

CFSR has two 1/2-degree grids. The 720x361 grid is for atmospheric data and the 720x360 grid is for ocean data. Why they offset the ocean a quarter degree from the atmosphere, I don't know