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

 statistics were computed. 



Results 



51. 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. 



42 



