The left panel in the three-dimension plot is a linear graph of the direction spec- 

 trum 5(0 ), which is the directional analog of the frequency spectrum. The di- 

 rection spectrum is defined by 



S(6J = t.S{f n ,Q m )df (19) 



Because 5(0 m ) represents total wave energy in each direction bin, it is a particu- 

 larly useful function from which to derive direction-sensitive characterizing pa- 

 rameters for a given frequency-direction spectrum as a whole. A set of such char- 

 acterizing parameters is defined in Chapter 4. 



Chapter 3 Primary Data Analysis 1 3 



