Table 1.— Intercorrelation of monthly mean sea level anomalies for selected west coast tide stations. Abbreviations refer to names 

 of stations shown in Figure 6. Correlation coefficients enclosed in parentheses are not significant at the 5% level. 





CAL 



TAL 



QPO SCZ 



MAN 



MZN 



ULA 



LA 



MTRY 



SF 



CC 



NEA 



TF 



PR 



SKA 



CAL 



1.00 































TAL 



.71 



1.00 





























QPO 



.49 



.57 



1.00 



























SCZ 



.50 



.44 



.55 1 



00 

























MAN 



.54 



.49 



.56 



72 



1.00 























MZN 



.64 



.43 



.55 



68 



.90 



1.00 





















ULA 



.22 



.26 



.43 



42 



.56 



.51 



1.00 



















LA 



.19 



.27 



.50 



48 



.63 



.63 



.79 



1.00 

















MTRY 



.23 



.21 



.43 



43 



.53 



.56 



.75 



.75 



1.00 















SF 



.25 



.17 



.36 



31 



.41 



.49 



.57 



.58 



.84 



1.00 













CC 



.24 



(.13) 



.31 



33 



.33 



.37 



.35 



.38 



.62 



.67 



1.00 











NEA 



(.00) 



(05) 



.26 



23 



.21 



.36 



.15 



.21 



.32 



.43 



.75 



1.00 









TF 



(.02) 



(-04) 



.24 



26 



.32 



41 



.27 



.36 



.40 



.47 



.76 



.94 



1.00 







PR 



(.03) 



(-00) 



.16 ( 



08) 



.28 



.37 



.16 



.24 



.21 



.27 



.34 



.67 



.73 



1.00 





SKA 



(-.10) 



( - 

































.10) 



.21 (.01) 



(.12) 



T) 



.17 



.15 



(.15) 



.17 



.20 



.49 



.55 



.81 



1.00 



60° N 



45° 



30° 



15° 



1 5°S 



0.0 .2 



Silica 



Prince Rupert 



To f ino 



Noah Bay 



Crescent City 



San Francisco 

 Monterey 

 Los Angeles 

 La Jolla 



Mo z a t Ian 

 Manza n i Mo 

 Salina Cruz 



1.0 



Quepos 



- Talc 



- Callo 



C or relat ion 



Figure 8.— Correlation of monthly sea level anomalies at selected west coast 

 tide stations relative to Monterey, Calif. 



mean sea levels were adjusted for monthly pressure effects by increas- 

 ing (decreasing) sea level 1.00 cm for every 1.00 mb increase 

 (decrease) of atmospheric pressure. The use of the more accurate value 

 of 0.995 cm/mb was not warranted in this study. The magnitude of the 

 pressure correction was determined by subtracting the long term mean 

 pressure for the period January' 1963 through December 1978 

 (1,016.85 mb) from the monthly mean atmospheric pressures. This 

 method removes the effects of seasonal and interannual pressure 

 changes. Mean monthly sea levels and sea level anomalies from which 

 the hydrostatic effect associated with monthly pressure anomalies have 

 been removed are referred to in this paper as adjusted sea levels. 



In general, the effect of atmospheric pressure on sea level is small 

 compared with the observed departures of sea level. In most months 

 the pressure correction is opposite in sign to the sea level anomaly and 

 reduces the variability of the sea level data. The effect of the static pres- 

 sure correction on the seasonal sea level is to reduce the range of the 

 monthly values, and to a lesser extent the seasonal range, but also to 

 shift the month of occurrence of highest sea level from September to 

 December. Pressure effects account for a portion of the sea level varia- 

 bility but significant nonbarometric residuals remain, indicating the 

 effects of dynamic as well as static processes. 



The effects of wind stress on sea level are two fold 1) the direct ele- 

 vation or depression of water by winds normal to the coast and 2) the 

 sea surface slopes created by offshore or onshore Ekman transport pro- 

 duced by winds parallel to the coast. The direct piling up of water 

 against the shore is commonly observed along coasts with wide, shal- 

 low continental shelves or long, narrow embayments. The magnitude 

 of this effect is dependent on basin configuration, surface wind veloc- 

 ity, depth of water, and the time scales considered. The continental 

 shelf in the Monterey area is quite narrow with deep water located close 

 inshore so that the effects of wind set-up are small. Defant (1961) 

 showed, for example, that a constant 10 m/s wind blowing overa basin 

 50 m deep would produce a sea surface slope of 6.6 cm/100 km. The 

 50 m contour near Monterey is <1.6 km offshore (Fig. 1), and the 

 magnitude of direct piling of water by the wind is thus less than the 

 range of error in tide measurements. In addition, monthly anomalies of 

 zonal (east/west) wind stress were found not to be significantly correl- 

 ated with monthly sea level anomalies at the 5% level of significance 

 (Table 2). Accordingly, elevation or depression of sea level by cross 

 shore wind stress is neglected in this analysis. 



The second effect of wind stress is that of sea surface slopes pro- 

 duced by offshore or onshore Ekman transport due to winds parallel to 

 the coast. According to conventional Ekman transport theory, net trans- 

 port is directed 90° to the right of the wind in the Northern Hemi- 

 sphere. In this study, offshore/onshore Ekman transport was found to 

 be significantly correlated with sea level (r = -0.42 in Table 2). The 

 inverse correlation indicates that offshore transport results in decreased 

 sea level and onshore transport in increased sea level. Meridional wind 

 stress is also significandy correlated with sea level (r =0.43), as 

 expected. Monthly anomalies of Sverdrup transport were found not to 

 be significandy correlated with monthly sea level anomalies at the 5% 

 level. 



Sea surface temperature and surface salinity are both significandy 

 correlated with monthly sea level anomalies (with correlation coeffi- 

 cients of 0.61 and -0.35). The signs of the correlations indicate that 



10 



