Breaker height is visually estimated to the nearest 10th of a foot. Direction 

 of wave approach to the shoreline is estimated visually to the nearest degree 

 using a hand-held protractor with its base oriented along the shoreline. Wind 

 observations include speed and direction. Direction is referred to the eight- 

 point compass directions by noting the sector from which the wind is blowing.' 

 A Dwyer wind meter is used to measure windspeed which is noted to the nearest 

 mile per hour. Longshore current speeds are estimated by pacing the shore- 

 parallel distance traveled in 1 minute of a dye packet thrown into the surf. 

 Current direction to the right or left of an observer looking seaward is noted. 

 Beach observations consist of estimates of the foreshore slope, measured to the 

 nearest degree with an Abney topographic hand level. Monthly sand samples are 

 taken from the swash zone at some sites. A typical instruction sheet provided 

 to LEO observers under the current program is given in Appendix A. 



2. Variation of Data Collection Techniques . 



Through experience gained during the operation, some collection procedures 

 were improved to meet specific needs. The most significant change was that of 

 wave angle determination. The compass sector method used in early observations 

 was changed to the coastal sector method which was later improved by the pro- 

 tractor method currently being used. Under the compass sector method an ob- 

 server determined the orientation of the shoreline with respect to north, then 

 recorded the wave approach from one of the eight primary compass directions. 

 The coastal sector method eliminated the need to determine the approximate 

 orientation of the shoreline. Direction of wave approach was estimated using 

 the simplified protractor shown in Figure 2. Examples of compass sector and 

 coastal sector output are shown in Figure 3. 



In the years following 1973 the coastal sector method was supplanted by the 

 protractor method. A protractor, which is printed on the back of the LEO form, 

 is oriented with its base parallel to the general shoreline orientation; the 

 observer sights along the protractor in the direction of wave approach and re- 

 cords the visually estimated direction to the nearest degree. Angles greater 

 than 90° represent waves approaching generally from the right and driving the 

 longshore current to the left, for an observer looking seaward. Angles less 

 than 90° represent waves approaching from the left and driving the longshore 

 current to the right. Shore-normal waves (wave crests parallel with shore) 

 are recorded as 90° angles. The protractor is shown in Figure 4. 



3. Standard Computer Output . 



LEO data are normally analyzed with data sets comprised of 1 year of obser- 

 vations. Where an accumulation of 2 or more years of data is available, it may 

 also be analyzed as a complete data set. 



As stated previously, this report makes the northern California LEO data 

 available for use to coastal planners, designers, and researchers. Because of 

 the quantity of data collected during the 1968-78 program it was not practi- 

 cal to present all the data analyses and summary formats available, however, 

 basic data summaries by year are given. 



a. Yearly Summary Report . The yearly summary report, as shown in Figure 3, 

 provides monthly averages of breaker height, breaker period, angle of breaker 

 approach to the shoreline, breaker type, longshore current velocity, foreshore 



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