WHAT IS THE NEW 2-D ETA GRID GDS INFORMATION?
The new ‘native’ Eta grid representation in GRIB follows the 2-D grid indexing that has been used by the model for some time. This is still staggered row by row, wind and mass, but the same number of points are in each row. This means that the number of points on the grid is now IM*JM (rather than IM*JM-JM/2). The “extra” point now included on every other row is not used during integration.