Observations from the lightship AFRUMBANK during the period 

 20 November to 10 December 1936, were also checked by measurements „ Ob- 

 server V is responsible for data up to Lfecember 3 and observer VI for 

 data thereafter o Figure 9 indicates that the wave heights estimated by- 

 observer V generally are of the right order of magnitude^ The estimated 

 values of low waves nearly always were below the measured values while 

 in the case of higher waves ^ agreement was better » Only in the case of 

 exceptionally high estimated waves do these values run appreciably 

 higher than those values computed from measured data by the method out- 

 lined above o Trie observer reported that the buoy of the recording 

 apparatus did not completely follow the motion of the water surface at 

 such high seas and that consequently the measurements were not exacts 

 Figure 10 gives a comparison of wave lengths based upon observations of 

 observer V vi^hose values for the wave length and frequency were approx- 

 imately the same for wind waves and swells. Observer VI did not give 

 frequency values for the period checked by measurement^ but noted that 

 it T/as not possible to distinguish wave crests due to wind and swells „ 

 During this period wind vraves and swells crossed over one another o Ob- 

 served wave lengths for wind yraves and svrells are compared to measured 

 values in figure 12, Figure 11 indicates a great discrepancy in the 

 estimates of observer VI of the wave heights in high seaso 



Comparison of Results of Observations from Various Lightships 



The results for the estimated wave heights from all points 

 of observation in the North sea were compared o Figure 14. represents 

 the data for the period 13-31 January 1937 j during which continuous 

 observations were made from all points , Observations came from the 

 lightships BOMUMRIFF, NORDERNEY, WESER, AUSSENJADE, MINSENTilR SAND, 

 EKMCENj AUSSENEIDER AJJD AMRMBANKo The location of these observation 

 stations is given on the map, figure 13o 



The wave height curves in figure 14. indicate the uniform 

 tendency for increase and decrease at all points of observation (note 

 rise of curves on the 23/1/37 )» Some of the changes in height are 

 displaced along the time axis and the relative ratios between heights 

 show some differences „ On 19 January, the maximum value occurred at 

 the lightship BDRKMRIFF which was farthest out at seac On the other 

 handj the highest values occurred on the 25, 26, 28, and 29 January 

 at the lightship NORDERNEY where the maximum wave reaches a height 

 of 3o5 meters o During this period all lightships in the mouth of the 

 Weser (with the exception of the AUSSENJADE) reported wave heights 

 between 2 and 3 meters o It is noteworthy that wave heights up to 

 3 meters were also reported from the lightship BREMEN which was 

 closest to shore, while during calmer weather wave heights at the 

 position were always lowero Observed wave-height data from these 

 lightships which were not checked by measurement cannot be used as a 

 basis for the evaluation of the effects of wind at the various ob- 

 servation points, and a corresponding comparison of wave length is 

 even less feasible « 



