height selected on the hour), and various extreme and/or mean water level 

 statistics were computed. 



Results 



Tides at the FRF are semidiurnal with both daily high and low tides 

 approximately equal. Tide height statistics are presented in Table 7. 

 Figure 17 plots the monthly tide statistics for all available data, and Figure 18 

 compares the distribution of daily high and low water levels and hourly tide 

 heights. The monthly or annual mean sea level (MSL) reported is the average 

 of the hourly heights, whereas the mean tide level is midway between mean 

 high water (MHW) and mean low water (MLW), which are the averages of 

 the daily high- and low-water levels, respectively, relative to NGVD. Mean 

 range (MR) is the difference between MHW and MLW levels, and the lowest 

 water level for the month is the extreme low (EL) water, while the highest 

 water level is the extreme high (EH) water level. 



NOTE: Due to a mistake in converting feet to centimeters the tide height 

 statistics from 1987 through 1993 (As published in the 1987 through 1993 

 Annual Data Summaries) found in Table 7 and Figure 17 were in error. 

 These have been corrected for this report. 



39 



Chapter 5 Tides and Water Levels 



