Atmosphere-Ocean Model Grid
The Atmosphere-Ocean Model divides the horizontal surface of the
Earth into grid cells of 5° in longitude by 4° in latitude. The 72
grid cells in longitude are numbered from west to east with the first
cell being between the International Date Line and 175°W. There are 46
grid cells in latitude because the triangular grid cells touching each
pole use only 2° in latitude. Grid cells are numbered from south to
north in latitude with the first cell being between the South Pole and
88°S.
The Atmosphere-Ocean Model uses the index I to number grid cells
in longitude and the index J to number grid cells in latitude. The
Model calls west longitude as negative longitude, calls east longitude
as positive longitude, calls south latitude as negative latitude, and
calls north latitude as positive latitude. Using these conventions,
grid cell (I,J) is between I*5-185 and I*5-180 degrees of longitude and
between J*4-96 and J*4-92 degrees of latitude. A location at X degrees
of longitude and Y degrees of latitude resides in grid cell
(37+X/5,24+Y/4) when these values are truncated to integers.
1 1 1 1 1 1 1 1
8 7 7 6 6 7 7 8
0 5 0 5 5 0 5 0
W W W W E E E E
90N +-------+-------+-------+ . . . . +-------+-------+-------+ 90N
| polar circle |
88N +-------+-------+-------+ . . . . +-------+-------+-------+ 88N
| | | | | | | |
| 1,45 | 2,45 | 3,45 | | 70,45 | 71,45 | 72,45 |
| | | | | | | |
84N +-------+-------+-------+ . . . . +-------+-------+-------+ 84N
| | | | | | | |
| 1,44 | 2,44 | 3,44 | | 70,44 | 71,44 | 72,44 |
| | | | | | | |
80N +-------+-------+-------+ . . . . +-------+-------+-------+ 80N
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .
80S +-------+-------+-------+ . . . . +-------+-------+-------+ 80S
| | | | | | | |
| 1,3 | 2,3 | 3,3 | | 70,3 | 71,3 | 72,3 |
| | | | | | | |
84S +-------+-------+-------+ . . . . +-------+-------+-------+ 84S
| | | | | | | |
| 1,2 | 2,2 | 3,2 | | 70,2 | 71,2 | 72,2 |
| | | | | | | |
88S +-------+-------+-------+ . . . . +-------+-------+-------+ 88S
| polar circle |
90S +-------+-------+-------+ . . . . +-------+-------+-------+ 90S
1 1 1 1 1 1 1 1
8 7 7 6 6 7 7 8
0 5 0 5 5 0 5 0
W W W W E E E E
2003/11/05