Atmosphere Grid Trivia. Note about the "NE" variable. This is the name of a Fortran variable and also used in CIME XML files to refer to cubed sphere grids. It is meaningless jargon to most people. For written documents we recommend referring to grids by their resolution in km. For the quasi-uniform cubed-sphere grid, average grid spacing at the equator is a good measure of the resolutions.
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For any spectral element grid with N elements, the number of unique points (physics columns) is (np-1)^2 * N + 2, where each element contains a np x np tensor product of Gauss-Lobatto points.
NE | common name | Resolution degrees | Resolution at equator (km) | Resolution at equator (miles) | N elements | N columns | factor over ne30 N columns |
|---|---|---|---|---|---|---|---|
4 | ultra low | 7.5 | 835 | 520 | 96 | 866 | |
11 | 2.7 | 304 | 190 | 726 | 6536 | ||
16 | 1.9 | 210 | 130 | 1536 | 13826 | ||
30 | low | 1.0 | 110 | 70 | 5400 | 48602 | 1x |
120 | high | 0.25 | 28 | 17.25 | 86400 | 777602 | 16x |
240 | 0.125 | 14 | 8.65 | 345600 | 3110402 (3.1M) | 64x | |
256 | 0.1171875 | 13 | 8.1 | 393216 | 3538946 (3.5M) | 73x | |
512 | 0.05859 | 6.5 | 4 | 1572864 (1.57M) | 14155778 (14.16M) | 291x | |
1024 | ultra high | 0.029297 | 3.25 | 2 | 6291456 (6.29M) | 56623106 (56.6M) | 1165x |
2048 | 0.014648 | 1.63 | 1 | 25165824 (25.2M) | 226492418 (226.5M) | 4660x | |
3600 | 0.0083333 | 0.925 | 0.58 | 77760000 (77.76M) | 699840002 (688.85M) | 14400x |
*All reported resolutions are average distances based on a third order cubed sphere spectral element domain using 4x4 Gauss-Labotto points (np=4).
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For the formulas, note that NP is normally 4 (ex. ne30np4) and NPG is normally 2 (ex. ne30pg2)
NE | np4 # physics columns | pg2 # physics columns | np4 approx grid spacing | pg2 approx grid spacing | np4 approx grid spacing | pg2 approx grid spacing |
|---|---|---|---|---|---|---|
4 | 866 | 384 | 7.50 | 11.25 | 834.9 | 1252.3 |
8 | 3,458 | 1,536 | 3.75 | 5.63 | 417.4 | 626.2 |
11 | 6,536 | 2,904 | 2.73 | 4.09 | 303.6 | 455.4 |
16 | 13,826 | 6,144 | 1.88 | 2.81 | 208.7 | 313.1 |
30 | 48,602 | 21,600 | 1.00 | 1.50 | 111.3 | 167.0 |
45 | 109,352 | 48,600 | 0.67 | 1.00 | 74.2 | 111.3 |
60 | 194,402 | 86,400 | 0.50 | 0.75 | 55.7 | 83.5 |
120 | 777,602 | 345,600 | 0.25 | 0.38 | 27.8 | 41.7 |
256 | 3,538,946 | 1,572,864 | 0.12 | 0.18 | 13.0 | 19.6 |
512 | 14,155,778 | 6,291,456 | 0.06 | 0.09 | 6.5 | 9.8 |
1024 | 56,623,106 | 25,165,824 | 0.03 | 0.04 | 3.3 | 4.9 |
2048 | 226,492,418 | 100,663,296 | 0.01 | 0.02 | 1.6 | 2.4 |