and editing. At this point, the program analyzes the data and prints a flag 



indicating there is a problem with the file. If the variance is less than 



2 

 0.001 m , the record is not analyzed. After editing, the first five moments 



of the distribution of sea surface elevations were again computed. A cosine 

 bell data window was applied to increase the resolution for the energy spec- 

 trum of the file; use of the data window is discussed by Harris (1974). After 

 application of the data window, the program computes the variance spectrum 

 (proportional to the energy spectrum) using the FFT procedure. After the data 

 files are analyzed, the results are eliminated for files that are flagged as 

 bad or appear inconsistent with simultaneous observations from nearby gage 

 sites. Frequently, the spectrum and/or distribution function of sea surface 

 elevations are examined to determine if the data were acceptable. After the 

 analysis results are edited, monthly summaries of wave heights and periods are 

 generated. 



46. Unless otherwise specified, wave height, in this report, refers to 



the energy-based parameter H (defined as four times the standard deviation 

 ° mo 



of the sea surface elevations) . Wave period T is defined as the period 

 associated with the maximum energy in the spectrum which is resolved by parti- 

 tioning the spectrum into frequency bands of equal width and determining the 

 band with the maximum energy density. The period reported is the reciprocal 

 of the center frequency (e.g. T = 1/frequency) of the spectral band. Since 

 the spectral bands are of equal frequency width, namely 0.010742 Hz (i.e. 

 11/1,024 sec), the analysis provides uniform resolution in frequency. How- 

 ever, the resolution in period is not uniform since the period intervals 

 become larger for lower frequencies. Because of combination with the varying 

 width of the period intervals, only a discrete set of period values is possi- 

 ble (Table 5) . Complete information about the energy contained in all fre- 

 quency bands can best be obtained by inspecting the full spectrum, examples of 

 which are included in Appendix C (Volume II) for Gage 625 during storm wave 

 conditions. 



Results 



Present year 



47. Spatial variation. The distribution of wave heights for all four 

 gages operated during the year is shown in Figure 11. For a given frequency 

 of occurrence, wave heights were highest at Gage 630 (located in the deepest 



31 



