Paper 5 



Monthly C L i rn at i c Data for the worLdr from CCEA/' or computed from 

 monthly mean pressure fields obtained from FN^C.^ 



Normal atmospheric pressures at each station were obtained 

 averaging monthly pressures for the entire period of record, 

 effects of monthly variations from this long-term pressure 

 were removed from sea level measurements by applying a correc 

 of 1 cm in sea level for each millibar deviation in atmosph 

 pressure. Sea level data for all stations north of razatlan 

 corrected in this manner^ with resultant small decreases in 

 range of sea level anomalies. Pressure deviations sout 

 Mazatlan were on the order of one millibar or less* not I 

 enounh to warrant correction because sea level measurements 

 a typical error of about 1 cm. 



by 

 The 

 mean 

 t ion 

 eric 

 were 

 the 

 h of 

 arge 

 have 



DISCUSSION 



The anomalies of corrected monthly mean sea level (Figs. 5.2-5.6) 

 exhibit remarkably coherent patterns in time and space. Perhaps 

 the most striking feature of the time series is the long-term 

 persistence and wide distribution of high sea level during the 

 period 1957-59. Evidence of anomalously high sea level extenos 

 from Calderar Chile/^ to Adakr AK. Similar periods of anomalously 

 high sea level can be seen in 1940-41 and 1971-73* and to a 

 lesser extent in 1951-52 and 1965-66. 



The simultaneous occurrence of these changes over such vast 

 distances suggests a relation to large-scale oceanic or atmos- 

 pheric disturbances. The periods of anomalously high sea levels 

 were also periods of anomalously warm sea surface temperatures 

 and are associated with El Nino occurrences in the eastern 

 tropical Pacific (Quinn 1976/ 1978). 



Such environmental changes can have dramatic effects on marine 

 fisheries. Along the coast of Peru* for example* large changes 

 in the distribution and abundance of anchoveta result from 

 adverse oceanog raph i c conditions associated with El Nino periods. 

 These conditions* combined with heavy exploitation* have resulted 

 in a decline of the fishery and have had major economic impact. 

 Radovich (1961) documented many changes in the distribution of 

 marine populations along the coast of California during the warm 

 water periods 1940-41 and 1957-59 which were associated with high 

 sea levels. He found a general northerly shift of southern 



'Center for Climatic and Environmental Assessment* Environmental 

 Data Service* NOAA* Columbia* MO 65201. 

 ■^Fleet Numerical U/eather Central* U.S. Navy* Monterey* CA 93940. 



54 



