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Interpolation of the surface geopotential (and hence, effectively,the orographic height) is affected by the changes to:
- the land sea-mask processing
- the default interpolation method
- the distance computation and selection of nearest points
HRES - O1280
The surface geopotential has been interpolated from the O1280 reduced Gaussian grid to regular lat-lon grids at different target resolutions using EMOSLIB and MIR.
- For the cases shown here, differences between MIR and EMOSLIB generally lie between+/-4500 m2/s2 (+/- 460 m)
- In general, more than 99.5% of points differ by less than +/-450 m2/s2 (+/-46 m)
- The largest differences occur close to the coasts and in areas of steep orography where the gradient of the surface geopotential field changes most rapidly
- Discounting differences due to land-sea mask processing, the differences between MIR and EMOSLIB generally lie between+/-1800 m2/s2 (+/-185 m) with differences for 99.5% of points being less than +/-160 m2/s2 (+/-16.5m)
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 25% 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 |
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0.1x0.1 | Maximum difference = 4200.527100 Minimum difference = -2743.472900 Mean absolute difference = 6.570708 Median absolute difference = 0.527100 Standard deviation = 34.616588 RMS of differences = 34.617696 Percentage of points with absolute difference < 10.00 = 90.423% < 100.00 = 98.791% < 500.00 = 99.920% < 1000.00 = 99.987%
| -4201.500000 : -3437.590909 - 0 ( 0.000000%) -3437.590909 : -2673.681818 - 2 ( 0.000031%) -2673.681818 : -1909.772727 - 20 ( 0.000308%) -1909.772727 : -1145.863636 - 225 ( 0.003470%) -1145.863636 : -381.954545 - 3618 ( 0.055802%) -381.954545 : 381.954545 - 6474512 ( 99.859831%) 381.954545 : 1145.863636 - 4889 ( 0.075406%) 1145.863636 : 1909.772727 - 277 ( 0.004272%) 1909.772727 : 2673.681818 - 38 ( 0.000586%) 2673.681818 : 3437.590909 - 15 ( 0.000231%) 3437.590909 : 4201.500000 - 4 ( 0.000062%) | | |
0.125x0.125 | Maximum difference = 3884.730225 Minimum difference = -2500.269775 Mean absolute difference = 6.497116 Median absolute difference = 0.730225 Standard deviation = 34.833189 RMS of differences = 34.834725 Percentage of points with absolute difference < 10.00 = 90.403% < 100.00 = 98.775% < 500.00 = 99.918% < 1000.00 = 99.986% | -3885.500000 : -3179.045455 - 0 ( 0.000000%) -3179.045455 : -2472.590909 - 1 ( 0.000024%) -2472.590909 : -1766.136364 - 16 ( 0.000386%) -1766.136364 : -1059.681818 - 178 ( 0.004289%) -1059.681818 : -353.227273 - 2709 ( 0.065276%) -353.227273 : 353.227273 - 4143208 ( 99.834413%) 353.227273 : 1059.681818 - 3697 ( 0.089083%) 1059.681818 : 1766.136364 - 219 ( 0.005277%) 1766.136364 : 2472.590909 - 33 ( 0.000795%) 2472.590909 : 3179.045455 - 15 ( 0.000361%) 3179.045455 : 3885.500000 - 4 ( 0.000096%) | | |
0.25x0.25 | Maximum difference = 2986.975342 Minimum difference = -2501.024658 Mean absolute difference = 6.421756 Median absolute difference = 0.024658 Standard deviation = 36.891598 RMS of differences = 36.893367 Percentage of points with absolute difference < 10.00 = 90.346% < 100.00 = 98.733% < 500.00 = 99.904% < 1000.00 = 99.984% | -2987.500000 : -2444.318182 - 1 ( 0.000096%) -2444.318182 : -1901.136364 - 4 ( 0.000385%) -1901.136364 : -1357.954545 - 23 ( 0.002215%) -1357.954545 : -814.772727 - 96 ( 0.009246%) -814.772727 : -271.590909 - 1174 ( 0.113076%) -271.590909 : 271.590909 - 1035253 ( 99.712302%) 271.590909 : 814.772727 - 1501 ( 0.144572%) 814.772727 : 1357.954545 - 150 ( 0.014448%) 1357.954545 : 1901.136364 - 23 ( 0.002215%) 1901.136364 : 2444.318182 - 9 ( 0.000867%) 2444.318182 : 2987.500000 - 6 ( 0.000578%) | | |
0.5x0.5 | Maximum difference = 2871.975342 Minimum difference = -4142.024658 Mean absolute difference = 7.259612 Median absolute difference = 0.024658 Standard deviation = 43.622669 RMS of differences = 43.624398 Percentage of points with absolute difference < 10.00 = 90.088% < 100.00 = 98.533% < 500.00 = 99.857% < 1000.00 = 99.975% | -4143.500000 : -3390.136364 - 1 ( 0.000385%) -3390.136364 : -2636.772727 - 0 ( 0.000000%) -2636.772727 : -1883.409091 - 3 ( 0.001154%) -1883.409091 : -1130.045455 - 20 ( 0.007695%) -1130.045455 : -376.681818 - 251 ( 0.096568%) -376.681818 : 376.681818 - 259309 ( 99.764928%) 376.681818 : 1130.045455 - 311 ( 0.119652%) 1130.045455 : 1883.409091 - 20 ( 0.007695%) 1883.409091 : 2636.772727 - 4 ( 0.001539%) 2636.772727 : 3390.136364 - 1 ( 0.000385%) 3390.136364 : 4143.500000 - 0 ( 0.000000%) | | |
1.0x1.0 | Maximum difference = 1291.310547 Minimum difference = -1724.689453 Mean absolute difference = 7.614173 Median absolute difference = 0.689453 Standard deviation = 41.118318 RMS of differences = 41.125978 Percentage of points with absolute difference < 10.00 = 90.020% < 100.00 = 98.465% < 500.00 = 99.848% < 1000.00 = 99.988% | -1725.500000 : -1411.772727 - 1 ( 0.001535%) -1411.772727 : -1098.045455 - 1 ( 0.001535%) -1098.045455 : -784.318182 - 10 ( 0.015347%) -784.318182 : -470.590909 - 28 ( 0.042971%) -470.590909 : -156.863636 - 221 ( 0.339165%) -156.863636 : 156.863636 - 64598 ( 99.137508%) 156.863636 : 470.590909 - 230 ( 0.352977%) 470.590909 : 784.318182 - 50 ( 0.076734%) 784.318182 : 1098.045455 - 16 ( 0.024555%) 1098.045455 : 1411.772727 - 5 ( 0.007673%) 1411.772727 : 1725.500000 - 0 ( 0.000000%) | | |