excess of 2.3 m at the nearshore Baylor location. On October 25th, peak condi- 

 tions of H = 3.5 m were experienced at the pier end Baylor; this resulted 

 from a northeaster coincident with a local perigean spring tide (see Miller 

 et al. 1980). The last storm of 1980 on 29 December produced significant wave 

 heights in excess of 2.9 m at the pier-end Baylor location (Miller et al. 

 1980). 

 Tidal data 



115. This section presents the FRF tide and water level data. The var- 

 ious tide height values and water level datums due to predominantly astronomi- 

 cal forces of the sun and moon are discussed, followed by discussions of the 

 extreme high- and low-water levels which were particularly influenced by 

 meteorological conditions. 



116. Monthly and annual tide statistics are shown in Table 8, with 1979 

 annual average and extremes included at the bottom for comparison. Tides at 

 the FRF are semidiurnal, and the average tide range for the year was 102 cm. 

 The average of all tide bights (msl) during the year, was 8 cm above NGVD. 

 Mean higher high water (mhhw) , the highest of the two daily high tide tide 

 levels, was 68 cm and exceeded the mhw value by 9 cm; mlw was -43 cm, and 

 mean lower low water (mllw) was -47 cm for the year. (All tide values unless 

 otherwise specified are referenced NGVD). The annual tide statistics for 

 1980 were very nearly the same as those for 1979. 



117. Mean and extreme tide levels are presented as a function of month 

 in Figure 19. The 5- to 6-month periodicity in the rise and fall of the mean 

 values presented are due in part to the inclination of the sun, a long-period 

 astronomical tide constituent commonly referred to as Ssa , which has a pe- 

 riodicity of approximately 6 months. An additional explanation for the pe- 

 riodicity observed may be (a) astronomical forces with annual periodicity and 

 (b) seasonal oscillation of the specific volume of the seawater as a function 

 of temperature, called the steric effect (see Pattullo et al. 1955). The 

 distribution of all hourly heights is presented relative to NGVD in Fig- 

 ure 20. Since the 1980 local MSL is 8 cm above NGVD, one can see that nega- 

 tive departures from the mean are larger than positive departures. Harris 

 (1981) indicates it is not unusual for the magnitude of positive and negative 

 departures from the mean to be unequal. 



118. Figure 21 shows the distribution of the daily highest and lowest 

 tide levels which occurred throughout the year. On 87 occasions, or 1 percent 



55 



