Differences for significant wave height

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

HRES WAM 0.125 degree reduced lat-lon grid

Significant wave height has been interpolated from the 0.125 degree reduced lat-lon grid to regular lat-lon grids at different target resolutions using EMOSLIB and MIR.

• The differences for more than 99.8% of grid points are less than 0.05m.
• The largest differences occur close 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.

TargetStatistics of differencesHistogram of differencesGlobalEurope
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%)

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%)

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%)

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%)