76. Visibility was measured with a 0.3-m-diam secci disk and, similar 

 to water temperature, variation was related to onshore and offshore winds. 

 Onshore winds moved warm clear surface water toward shore, while offshore 

 winds brought up colder bottom water with large concentrations of suspended 

 matter. 



Present year 



77. Figure 38 presents the surface visibility values for the year. 

 Large variations were common, and visibility less than 1 m was expected in any 

 month. 



10n 

 9-1 

 B-, 

 7-j 

 6-i 

 5-i 



*■: 

 3- 



; 



2-. 



1- 



E 



_i 

 m 



> 



JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 

 1985 



MONTH 



Figure 38. Daily sea surface water visibility, 1985 



Present versus past years 



78. In general, visibility was higher than in prior years. In particu- 

 lar, during October the monthly mean was 2.7 m, over 1.5 m higher than the 

 average for past Octobers (Figure 39). The annual mean was 0.34 m above that 

 during prior years (Table 10). 



All years 



79. Throughout the year the visibility averages over 2 m with an asso- 

 ciated 1.1-m standard deviation (Table 10). During June and July the visibil- 

 ity was over 3.6 m (standard deviation over 1.5 m) , while during November the 

 average is under 1 m, and the deviation is only 0.5 m. Figure 40 shows the 



61 



