ANALYSIS OF NON-UNIFORM, SHORT-CRESTED OCEAN WAVES FOR DEPTH DETERMINATION, BASED ON THE WAVE VELOCITY METHOD, FROM TIMED VERTICAL PHOTOGRAPHS TAKEN OVER CRATSOP SPIT, OREGON
CALIFORNIA UNIV BERKELEY WAVE RESEARCH LAB
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Timed vertical aerial photographs of surf in the vicinities of Monterey and Oceanside, Cal., and of Clatsop Spit, Oregon were examined. Only those taken at Clatsop Spit exhibited a short-crested, nonuniform wave pattern the other 2 areas indicated long crested uniform waves. Five of 7 sorties flown over Clatsop Spit were analyzed for wave velocity and for depths. The equationC2gd, where C is the velocity of the short crested wave and d is the constant depth, was used for determining depths between breaker zone and the shore. Three methods were followed in computing depths outside the breaker zone 1 A modification was made of J. W. Johnsons method U. of Calif. IER. report, Oct. 7, 1949. 2 An arithmetical solution for the instantaneous velocity of the wave crests was obtained by tabulating distances vs times and using third differences, and computing each individual wave length at a point, the point being the position of the crest on the range line. The wave length at the point was determined by interpolation rather than by an averaging process. 3 Average velocities and periods were determined as in Johnsons method, but wave lengths at the crest positions were determined by interpolation as in 2. The computed depths were too small except for those determined for sortie 55A. This sortie exhibited relatively short period waves, of the order of 10 sec. Sortie 59A showed about the same period, but study indicated that the resulting profiles form this sortie were better than any of the others. The photographs in the 7 groups were generally of about the same photographic quality the wave crests stood equallu well, the tone was the same, and the scale variations were of the same magnitude.
- Physical and Dynamic Oceanography