January to March and October to December are times of high, generally longer, 
period storm waves approaching from the north. The spring and summer are 
characteristic of low southern seas. Annual distributions of wave height and 
period for 3 years of data are relatively stable. Seasonal variations are on 
the order of 0.5 to 1 percent, and monthly changes may be even greater. 
Current Data 
89. Spatial and temporal variations of longshore surface currents are 
discussed in this section. Surface current speed and direction at the FRF are 
influenced by winds, waves, and, indirectly, bottom topography. The extent of 
the respective influence varies daily. However, winds tend to dominate the 
currents at the seaward end of the pier, while the breaker angle and height 
dominate within the surf zone. During extreme wave conditions, the seaward 
end of the pier is within the breaker zone; consequently, currents measured 
there are strongly influenced by waves. The effect of the bottom topography 
is such that under certain conditions rip currents develop which interrupt the 
general flow of the alongshore current. The trough under the pier is a pre- 
ferred location for such currents, and some were measured in excess of 
1 m/sec. This report concentrates on the long-term alongshore currents, since 
a complete study of rip currents would require intensive measurements over a 
relatively short time scale. 
90. Surface current measurements were made daily at about 0700 EST by 
timing the movement of dye patches at three locations: (a) the seaward end of 
the pier; (b) the midsurf zone position under the pier; and (c) along the 
beach 500 m updrift of the pier. 
Present data year 
91. Spatial variability. Since the relative influences of wind speed 
and direction and breaker angle on nearshore surface currents vary with loca- 
tion at the FRF, there is significant variability between the mean monthly and 
annual values for these locations (Figure 22) and the daily measurements of 
surface currents (Figure 23). 
92. Currents at the seaward end of the pier were usually lower than 
those at the midsurf position (midway between the seawardmost breaker position 
and the beach) and consistently southward throughout the year. At the midsurf 
location, currents were fastest and varied from southward to northward with 
season as the wave angles varied (paragraph 80). Currents measured from the 
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