MAR.1973 
Figure 20. Diagram of winds recorded at Atlantic City, March 
1973, showing strong southwest winds followed by 
a northeast storm. Erosion was not particularly 
severe on Long Beach Island. 
b. Seasonal Changes. There is a definite seasonal cycle associated with 
the frequency and intensity of storms recorded at the Atlantic City reporting 
station (Fig. 10). West coast beaches respond to seasonal differences in wave 
climate caused by winter storms and exhibit a distinct bimodal character, 
being eroded with concave-upward profiles during winter and convex-upward pro- 
files in summer (Shepard, 1950; Komar, 1976; Fox and Davis, 1978). The sea- 
sonal signal, if it exists, may also be detected in the empirical eigenfunction 
analysis. The seasonal cycles are clearly discernible in the second temporal 
eigenfunction of Aubrey (1978) from studies conducted on Torrey Pines Beach. 
If the record is demeaned, a strong seasonal signal should show in the first 
beach eigenfunction. The ideal record from which to extract the seasonal sig- 
nal is one that is evenly and often sampled during all seasons. This requires 
at least monthly surveys of the profile sites. The sampling distribution for 
Long Beach Island was not evenly distributed as shown in Figure 4. Summer sea- 
sons, particularly during 1964-69, were infrequently sampled with some seasons 
missed completely. The other seasons were more frequently sampled since more 
beach changes were expected. 
Several periods of frequent sampling were selected during 1963 and again 
in 1969-71. Eigenfunction analysis was performed on selected profiles not 
directly adjacent to groins to determine a seasonal variation. A definite 
seasonal variability is seen in the first temporal eigenfunction (Fig. 21) with 
mean removed. The trend is not as marked as on west coast beaches. Profile 
lines 5 and 11 show a low at the beginning of 1970 and a rise in the midyear. 
A similar pattern is seen in 1971. Profiles 14 and 16 do not show as marked a 
trend and appear to be out of phase with the other profile lines. Whether this 
is an opposite seasonal trend or the result of a sign ambiguity in the eigen- 
function analysis is under study. However, the seasonal cycle can be seen in 
43 
