60 
KLIWA$ 60 
ICTP REGCM3 KNMI RACM02 METNO HIRHAM HC HodRM3Q0 
HC HadRM3Q16 HC HodRM3Q3 MPI REMO SMHI RCA 
Relative frequency of wind speed classes 
(= length of spoke) 
0 5 .0 t ' 
Fig. 3.4.2.: Wind roses from ERA-40 data (orange) compared to RCM-data (blue) in the northwestern area of the North Sea area for the period 1971-2000. 
Length of each branch is related to the frequency of occurrence of the respective wind direction, see legend for relation between frequencies and lengths. 
Width of each branch broadens with increasing speed range. Numbers in circles denote frequencies of calm winds.