Interpolation of significant wave height is affected by the changes to
- the default interpolation method
- the distance computation and selection of nearest points
- the handling of missing values
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HRES WAM 0.125 degree reduced lat-lon grid
Significant wave height has been interpolated from the 0.125 degree reduced lat-lon grid target grid to regular lat-lon grids at different target resolutions using EMOSLIB and MIR.
- The differences for more than 99% 99.8% of grid points are less than 20Pa and in the cases presented here all differences are less than 1 hPa0.05m.
- The largest differences occur in regions of high orography with the field gradient changes most rapidly.Larger differences are also seen in the lower resolution target grids (0.5ºx0.5º and 1.0ºx1.0º) at the polar latitudes (90ºN and 90ºS) which arise from the different handling of the interpolation at the polesclose to the coasts and ice shelves. These are due to the different distance computation and selection of nearest points and different handling of missing values in the interpolation formula.
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 | Statistics of differences | Histogram of differences | Global | Europe |
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0.125x0.125 | Maximum difference = 1.139648 Minimum difference = -1.192383 Mean absolute difference = 0.000186 Median absolute difference = 0.000000 Standard deviation = 0.005439 RMS of differences = 0.005439 Percentage of points with absolute difference < 0.05 = 99.895% < 0.10 = 99.953% < 0.50 = 99.999% | -1.2 : -1.1 - 1 ( 0.000024%) -1.1 : -1.0 - 1 ( 0.000024%) -1.0 : -0.9 - 4 ( 0.000096%) -0.9 : -0.8 - 3 ( 0.000072%) -0.8 : -0.7 - 3 ( 0.000072%) -0.7 : -0.6 - 7 ( 0.000169%) -0.6 : -0.5 - 10 ( 0.000241%) -0.5 : -0.4 - 26 ( 0.000626%) -0.4 : -0.3 - 70 ( 0.001687%) -0.3 : -0.2 - 182 ( 0.004385%) -0.2 : -0.1 - 763 ( 0.018385%) -0.1 : 0.0 - 42440 ( 1.022631%) 0.0 : 0.1 - 4105684 ( 98.930237%) 0.1 : 0.2 - 593 ( 0.014289%) 0.2 : 0.3 - 167 ( 0.004024%) 0.3 : 0.4 - 58 ( 0.001398%) 0.4 : 0.5 - 36 ( 0.000867%) 0.5 : 0.6 - 14 ( 0.000337%) 0.6 : 0.7 - 4 ( 0.000096%) 0.7 : 0.8 - 9 ( 0.000217%) 0.8 : 0.9 - 2 ( 0.000048%) 0.9 : 1.0 - 1 ( 0.000024%) 1.0 : 1.1 - 1 ( 0.000024%) 1.1 : 1.2 - 1 ( 0.000024%) | Image Added
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0.25x0.25 | Maximum difference = 1.139648 Minimum difference = -0.675537 Mean absolute difference = 0.000182 Median absolute difference = 0.000000 Standard deviation = 0.005373 RMS of differences = 0.005373 Percentage of points with absolute difference < 0.05 = 99.897% < 0.10 = 99.953% < 0.50 = 99.999% | -1.2 : -1.1 - 0 ( 0.000000%) -1.1 : -1.0 - 0 ( 0.000000%) -1.0 : -0.9 - 0 ( 0.000000%) -0.9 : -0.8 - 0 ( 0.000000%) -0.8 : -0.7 - 0 ( 0.000000%) -0.7 : -0.6 - 4 ( 0.000385%) -0.6 : -0.5 - 1 ( 0.000096%) -0.5 : -0.4 - 8 ( 0.000771%) -0.4 : -0.3 - 17 ( 0.001637%) -0.3 : -0.2 - 50 ( 0.004816%) -0.2 : -0.1 - 180 ( 0.017337%) -0.1 : 0.0 - 10962 ( 1.055825%) 0.0 : 0.1 - 1026794 ( 98.897557%) 0.1 : 0.2 - 142 ( 0.013677%) 0.2 : 0.3 - 44 ( 0.004238%) 0.3 : 0.4 - 20 ( 0.001926%) 0.4 : 0.5 - 9 ( 0.000867%) 0.5 : 0.6 - 4 ( 0.000385%) 0.6 : 0.7 - 1 ( 0.000096%) 0.7 : 0.8 - 3 ( 0.000289%) 0.8 : 0.9 - 0 ( 0.000000%) 0.9 : 1.0 - 0 ( 0.000000%) 1.0 : 1.1 - 0 ( 0.000000%) 1.1 : 1.2 - 1 ( 0.000096%) | Image Added
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0.5x0.5 | Maximum difference = 0.535156 Minimum difference = -0.661621 Mean absolute difference = 0.000189 Median absolute difference = 0.000000 Standard deviation = 0.005269 RMS of differences = 0.005269 Percentage of points with absolute difference < 0.05 = 99.889% < 0.10 = 99.952% < 0.50 = 99.999% | -0.7 : -0.6 - 1 ( 0.000385%) -0.6 : -0.5 - 0 ( 0.000000%) -0.5 : -0.4 - 1 ( 0.000385%) -0.4 : -0.3 - 6 ( 0.002308%) -0.3 : -0.2 - 17 ( 0.006540%) -0.2 : -0.1 - 40 ( 0.015389%) -0.1 : 0.0 - 2821 ( 1.085334%) 0.0 : 0.1 - 256974 ( 98.866574%) 0.1 : 0.2 - 42 ( 0.016159%) 0.2 : 0.3 - 9 ( 0.003463%) 0.3 : 0.4 - 5 ( 0.001924%) 0.4 : 0.5 - 2 ( 0.000769%) 0.5 : 0.6 - 2 ( 0.000769%) 0.6 : 0.7 - 0 ( 0.000000%) | Image Added
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1.0x1.0 | Maximum difference = 0.424805 Minimum difference = -0.413086 Mean absolute difference = 0.000183 Median absolute difference = 0.000000 Standard deviation = 0.005198 RMS of differences = 0.005198 Percentage of points with absolute difference < 0.05 = 99.902% < 0.10 = 99.954% < 0.50 = 100.000% | -0.5 : -0.4 - 1 ( 0.001535%) -0.4 : -0.3 - 0 ( 0.000000%) -0.3 : -0.2 - 3 ( 0.004604%) -0.2 : -0.1 - 7 ( 0.010743%) -0.1 : 0.0 - 704 ( 1.080417%) 0.0 : 0.1 - 64426 ( 98.873542%) 0.1 : 0.2 - 11 ( 0.016882%) 0.2 : 0.3 - 5 ( 0.007673%) 0.3 : 0.4 - 2 ( 0.003069%) 0.4 : 0.5 - 1 ( 0.001535%) | Image Added
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