The page show results from downscaling: mapping from a high resolution grid (ne120pg2) to a much lower resolution grid (ne3pg2)
We use the TempestRemap Y16_32 spherical harmonic based test function:
When plotted on the original ne120pg2 grid, the Y16_32 function can be see to have 16 oscillations in the mid-latitude. On the ne3pg2 grid, we have approximately 24 cells along 45N or 45S, and thus this grid is far too coarse to capture the Y16_32 oscillations.
Grid | Contour Plot |
|---|---|
Reference plot: Y16_32 plotted from the ne120pg2 grid This particular function ranges from 1 to 3. |  |
bilinear map ne120pg2 → ne3pg2 The wave number 16 mode aliases onto a wave number 4 mode that has little similarity to the original function |  |
integrated bilinear map ne120pg2 → ne3pg2 The wave still aliases onto a wave number 4 pattern, but the target grid’s large cells mean that any cell integrated approach will be integrating over much of the original oscillation, resulting in a much weaker save. |  |
mono / aave map ne120pg2 → ne3pg2 Nearly identical to integrated bilinear |  |