120 T. Spangehl et al.: Intercomparing the quality of recent reanalyses for offshore wind farm planning
Figure 4. Hourly wind speed at 100 m for model based products at FINO1 grid points during windstorm CHRISTIAN. Results are shown
for (blue solid curve) COSMO-REA6, (purple solid curve) CERRA-fc, (purple solid thin curves) CERRA-EDA, (cyan solid curve) ERA5,
(cyan dashed curve) HoKliSim-De and (red solid curve) NEWA. Results obtained from FINO1 measurements at 102 m (10 min averages)
are additionally shown (bold black dashed curve). The time period is (a) 25–31 October 2013 and (b) 28 October 2013.
3.2.1 Distribution of biases
For the ten-year time period comparison against the Scat-
terometer and Model (e5) (CMEMS) dataset the median
bias is nearly zero for ERA5 and COSMO-REA6 (Fig. 5,
top left panel). In 50 % of the cases (lower to upper quar-
tile range indicated by the blue boxes) the bias is within
?0.2 to 0.2 m s?1. Larger biases are found as indicated by
the whiskers.
The maximum negative bias of ERA5 is ?3.1 m s?1 in
contrast to the maximum positive bias of 0.9 m s?1 (Table 4).
A systematic shift towards positive bias values is found for
CERRA as indicated by the median bias of 0.2 m s?1 and
the lower to upper quartile ranging from 0.05 to 0.35 m s?1.
Compared to ERA5 a similar maximum negative bias of
?3.1 m s?1 is found compared to a larger maximum posi-
tive bias of 2.0 m s?1. Larger maximum negative and pos-
itive biases of ?3.7 and 2.2 m s?1 are found for COSMO-
REA6 (Table 4). Contrary to CERRA the bias distribution of
HoKliSim-De shows a shift towards negative values with the
median bias of about ?0.2 m s?1 (Fig. 5, top left panel).
A slight shift of the bias distribution towards positive
values is seen for ERA5 and COSMO-REA6 when using
the HOAPS dataset as reference (Fig. 5, right panels). For
CERRA the shift towards positive bias values seen earlier
is confirmed. HoKliSim-De shows a marginal shift towards
negative bias values. Results confirm that HOAPS shows
Adv. Sci. Res., 20, 109–128, 2023 https://doi.org/10.5194/asr-20-109-2023
