HARACTERISTICS OF MEASURED WAVE ACTION ON THE BASIS 



OF THE FREQUENCY DISTRIBUTION OF WAVE LENGTH, 



WAVE HEIGHT, AND STEEPNESS 



The following translated paper appeared in limited issue 

 as Technical Report HE-116-105, Fluid Mechanics Laboratory, 

 University of California „ It is reproduced here to bring 

 the concepts therein to the attention of research workers 

 and others having an interest in ocean waves The origi- 

 nal paper "Kennzeichnung des gemessenen Seegangs auf Grund 

 der Haufigkeitsverteilung von Wellenhbhe, Wellenl'ange und 

 Steilheit" was prepared by H. Hiring and was published in 

 Technische Bsrichte 4 5 194-0, 



Since 1932, a wave measuring instrument (1) has been used for the 

 measurement of wave action and has permitted the continuous recording of a 

 great amount of data. The results of numerous measurements that have been 

 made, are satisfactory, since the customary description of measured waves has 

 been shown to be incomplete <, For the designation of height, H, the measured 

 wave has, in general, been taken as the height of the largest measured waves, 

 or the height which was exceeded by 10 or 20 waves in the hour,' The wave 

 length, L (in meters), is obtained from the period, T (in seconds), which the 

 instrument records, by the trochoidal wave theory relationship L - 1„56T2. 

 The wave length of the measured waves is designated by means of the mean 

 length of the 10 or 20 highest waves, or. by the mean length, which resulted 

 from a number of large waves counted in a definite time (2). The steepness 

 of the waves, that is, the ratio H/L, is seldom specified and is very inaccu- 

 rate in the case of the correlation of a few chosen wave heights to one of 

 the above mentioned mean wave lengths „ Frequently the determined wave meas- 

 urements have been correlated ?fith a wave scale (3), and the measured wave 

 action estimated by this wave scale All of these methods do not describe 

 the complete picture of wave action and exclude a numerical comparison of 

 different wave actions c 



Since it is not possible to characterize the wave action, which a 

 varied collection of higher and longer waves represents, in its entirety by 

 the specification of a quantity such as H max , or E mean (which remains inde- 

 pendent of the number and quantity of all occurring waves), only the evalua- 

 tion of a great number of measured waves according to height and length can 

 yield a satisfactory result. The results may be presented best in the form 

 of a frequency curve, whereby the wave lengths and heights can be specified 

 as known values which are prominent in relation to the frequency of their 

 occurrence, either absolute or as percent in reference to the total number 

 of measured waves. 



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