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Figure 7.— Continued. 



the following paragraphs each variable will be treated in turn and the 

 results of the correlation analysis will be discussed. 



The effect on sea level of changes in atmospheric pressure over the 

 oceans has been examined by a number of authors (Patuilo et al. 

 1955; Saur 1962; Roden 1960). An increase (decrease) in atmo- 

 spheric pressure results in a decrease (increase) in sea level . The pres- 

 sure effect can be quite large in some areas, particularly in the Gulf of 

 Alaska where winter storms are intense or along the Gulf or Atlantic 

 coasts of the United States during the passage of hurricanes. 



The isostatic contribution of atmospheric pressure variations to vari- 

 ations in sea level is computed from the hydrostatic equation Ap= - 

 pgAh where Ap is the change in atmospheric pressure in millibars 

 (mb) , p is the density of water in g/cm 1 , g is the acceleration of gravity 

 in cm/s 2 , and Ah is the change in sea level in centimeters. Applying this 

 equation to seawater of density 1 .025 g/cm 1 and using 980.7 cm/s : as 

 the acceleration of gravity, we find that an increase in atmospheric pres- 

 sure of I mb will result in a 0.995 cm depression of sea level. 



The annual seasonal range of monthly mean atmospheric pressure 

 at Monterey during the period 1963-78 was 7.3 mb. but pressure 

 changes several times greater than this are not uncommon during the 

 passage of intense winter storms. Thus, the effect of atmospheric 

 pressure is expected to account for a significant portion of sea level 

 variability near Monterey. 



Maixner (1973) examined hourly data recorded from the Monterey 

 tide gage during the year 1971 and concluded that sea level responds 

 rapidly (within several hours) to pressure changes in an approxi- 

 mately hydrostatic manner. The coefficient of correlation between 

 monthly mean sea level anomalies and pressure anomalies, based on 

 180 mo of simultaneous data from the period July 1963 through 

 December 1978. was found in the present study to be -0.69 (Table 2). 

 The relatively large negative correlation indicates a significant 

 response of sea level to pressure. 



It is desirable to remove the static effects of atmospheric pressure 

 from the monthly sea level data so that the influence on sea level of 

 other variables can be readily examined. To accomplish this, monthly 



