The number of trignometric terms needed to describe the astronomical tide varies with 

 the location. More terms are needed where the tide must travel a great distance over shallow 

 water than when the tide station is near the open sea. Additional terms may be needed to 

 obtain an adequate representation when the tidal range is large ratlier than small. In the 

 United States, 37 standard constituents are found to be adequate for most tide stations 

 (Schureman, 1941). 

 6. Classical Harmonic Constituents of the Tide. 



Tidal constituents regularly used by the NOS, with their frequencies expressed as degrees 

 per hour and the symbols normally associated with each, are given in Table 2. The symbols 

 may be used to identify the frequency, amplitude, or phase of tlie constituent. Symbols 

 with subscripts 1, 2, 3, 4, 6 or 8 indicate the approximate number of cycles per tidal day; 

 symbols without subscripts indicate periods much longer than 24 hours. 



Table 2. Tidal constituents commonly used by the National Ocean Survey (NOS). 



Symbol 



Frequency 



Symbol 



Frequency 



(0) 



(solar hr) 





(0) 



(solar hr) 



M2 



28.984 



1042 



Mm 



0.544 



3747 



S2 



30.000 



0000 



Ssa 



0.082 



1373 



N2 



28.439 



7295 



Sa 



0.041 



0686 



Ki 



15.041 



0686 



Msy 



1.015 



8958 



M4 



57.968 



2084 



Mf 



1.098 



0331 



Oi 



13.943 



0356 



Pi 



13.471 



5145 



M6 



86.952 



3127 



Ql 



13.398 



6609 



(MK3) 



44.025 



1729 



T2 



29.958 



9333 



S4 



60.000 



0000 



R2 



30.041 



0667 



(MN)4 



57.423 



8337 



(20)i 



12.854 



2862 



I'a 



28.512 



5831 



Pi 



14.958 



9314 



S6 



90.000 



0000 



(2SM)2 



31.015 



8958 



M2 



27.968 



2084 



M3 



43.476 



1563 



(2N)2 



27.895 



3548 



L2 



29.528 



4789 



(00)1 



16.139 



1017 



(2MK)3 



42.927 



1398 



X2 



29.455 



6253 



K2 



30.082 



1373 



Si 



15.000 



0000 



Me 



115.936 



4169 



Ml 



14.496 



6939 



(MS)4 



58.984 



1042 



Jl 



15.585 



4433 









A quantitative definition of the type of tide (diurnal, semidiurnal, or mixed) may be 

 expressed by 



_ A(K^) + A(O^) 

 ^ ~ A(M2)+ A(S2) 



(22) 



34 



