Interpolation of temperature at 1000 hPa affected by:
- MIR using an intermediate full (regular) Gaussian grid at a resolution corresponding to the target lat-lon resolution for the spectral to grid transformation followed by grid-to-grid interpolation
- MIR using a more accurate truncation of the spectral series corresponding to the target grid resolution to avoid ripples from aliasing effects
HRES T1279
- For transformations to high resolution target grids (0.1x0.1 and 0.125x0.125) for which no spectral truncation occurs
- differences are at most +/-3K
- differences are smaller than +/-1K for more than 99% of grid points
- For transformations to lower resolution target grids
- the maximum and minimum differences are significantly larger.
- differences are smaller than +/-2K for more than 99% of grid points
- larger differences are due to sub-optimal default truncation of the spectral series used by EMOSLIB:
- EMOSLIB uses truncation=T799 for a 0.25x0.25 target grid compared to the theoretical ideal used by MIR of truncation=T719
- EMOSLIB uses truncation=T319 for a 0.5x0.5 target grid compared to the theoretical ideal used by MIR of truncation=T359
- EMOSLIB uses truncation=T213 for a 1.0x1.0 target grid compared to the theoretical ideal used by MIR of truncation=T179
- Generally, the use of the intermediate grid with MIR produces smoother fields.
The plots show the differences with the contours chosen on a logarithmic scale to enhance the smaller differences. Differences smaller than 0.1% of the field range are not shown. Grid points where the absolute difference is greater than 50% of the maximum absolute difference are indicated with red (EMOSLIB greater than MIR) and blue (EMOSLIB less than MIR) filled circles.
Target resolution | Statistics of differences | Histogram of differences | Global | Europe |
---|---|---|---|---|
0.1x0.1 | Maximum difference = 1.693253 Percentage of points with absolute difference < 0.5 = 99.914% | -2.5 : -1.5 - 4 ( 0.000062%) | ||
0.125x0.125 | Maximum difference = 2.510147 Percentage of points with absolute difference < 0.5 = 99.703% | -3.5 : -2.5 - 2 ( 0.000048%) | ||
0.25x0.25 | Maximum difference = 8.004074 Percentage of points with absolute difference < 0.5 = 96.187% | -8.5 : -7.5 - 0 ( 0.000000%) | ||
0.5x0.5 | Maximum difference = 13.379105 Percentage of points with absolute difference < 0.5 = 90.877% | -13.5 : -12.5 - 0 ( 0.000000%) 0 ( 0.000000%) | ||
1.0x1.0 | Maximum difference = 9.762299 Percentage of points with absolute difference < 0.5 = 81.599% | -10.5 : -9.5 - 2 ( 0.003069%) |