o 



c 

 a> 



<D 



.C 



o 

 u 



en 



0. 



a 6 6 p 



.5 .6 Cpd 



1.0- 



.8- O 

 .6- 

 ■ 4- 



.2- 



0.0 I 



oo o o O O o 



o o 



■95% 



h — I — h 



0.1 .2 



.5 .6 Cpd 



-I 



180 



-0 J 



oUolooflo JooJpop 



95% 



Figure 14.— Spectral plots of 6-h atmospheric pressure (Press) and unadjusted 

 sea level (SL) for the upwelling period (df = 100) at Monterey, Calif. The hori- 

 zontal axes are frequency in cycles per day (cpd). The upper plot shows spectral 

 density of pressure (in mrP/cpd) and sea level (in cm 2 /cpd); the middle plot 

 shows the squared coherence of the two series; and the lower plot shows the 

 phase. 



6 cpd 



1.0-1 



CD 



O .6- 



c 



CD 



o 



CJ 



.4- 



.2- 



0.0 



O o 



-Q-O- 



O O 



95% 



-q — i — h 



0.1 



.4 .5 .6Cpd 



180-1 



CD 



10 



CD 

 -C 

 0_ 



— 180 — ' 



° O o 



OOO o°° o o 



o_o_ 



O .1 



$ 95% 



>cpd 



Figure 15. — Spectral plots of 6-h meridional wind stress (VVS) and adjusted sea 

 level (SL) for the winter period (df = 90) at Monterey, Calif. The horizontal 

 axes are frequency in cycles per day (cpd). The upper plot shows spectral den- 

 sity of wind stress (in (dynes/cm 2 ) 2 /cpd) and sea level (in cm : /cpd); the middle 

 plot shows the squared coherence of the two series; and the lower plot show s the 

 phase. 



tions along the coast are both thought to result from variations in coastal 

 current flow. 



Analysis of 6-h sea level and atmospheric pressure observations 

 shows that the power spectra in the winter season are more energetic 

 than those of the upwelling season, and that most of the energy occurs 

 at low frequencies (periods longer than 12 d). Coherence between sea 



level and atmospheric pressure is significant and independent of fre- 

 quency. This and a nearly constant 180° phase relationship between 

 these 6-h data sets reflects the inverse response between sea level and 

 atmospheric pressure expected from the hydrostatic relationship. The 

 power spectra for 6-h meridional wind stress also show a concentration 

 of energy at low frequencies and are most energetic in winter; however, 

 coherence between the local wind stress and sea level is generally low. 



19 



