Square 2 . Off central Mexico - little expected 

 temperature change in time and 

 space. 



Squares 3 and 4 . Gulfs of Tehuantepec and 

 Panama - large expected tempera- 

 ture variability, especially in 

 winter months because of coastal 

 upwelling, and also thermal ridging 

 in the case of the Gulf of Tehuan- 

 tepec. 



Square 5 . Off Gulf of Guayaquil - sharp hori- 

 zontal temperature gradient and 

 expected large temperature change 

 in time and space. This region had 

 comparatively few observations 

 per unit area. 



Standard deviations were computed for the 

 individual monthly means and the correspond- 

 ing 12-year means for January, April, July, 

 and October of each year. The reliabilities of 

 these means as indicated by the 95 percent 

 confidence interval, for the index squares 

 described above, are shown in table 1. Aster- 

 isks denote cases where the presence of 

 gross errors in the source data were respon- 

 sible for the wide confidence intervals. Ail 

 other cases having noticeably wide limits 

 had relatively small numbers of observa- 

 tions. 



LITERATURE CITED 



BJERKNES, JACOB. 



1961. El Nino study based on analysis of 

 ocean surface temperatures 1935-1957. 

 Inter-American Tropical Tuna Com- 

 mission, vol. 5, no. 3, p. 219-272. 



JOHNSON, JAMES H. 



1961. Sea surface temperature monthly 

 average and anomaly charts, north- 

 eastern Pacific Ocean, 1947-1958. U.S. 

 Fish and Wildlife Service, Special Scien- 

 tific Report — Fisheries No. 385, 56 p. 



RODEWALD, MARTIN 



1958. Die Anomalie der Wassertemperatur 

 und der Zirkulation im Nordpazifischen 

 Ozean und an der Kiiste Perus im 

 Jahre 1955. Deutsche Hydrographische 

 Zeitschrift, Band 11, Heft 2, p. 78-82. 



WOOSTER, WARREN S. 



1961. Yearly changes in the Peru Current. 

 Limnology and Oceanography, vol. 6, 

 no. 2, p. 222-226. 



U. S. DEPARTMENT OF COMMERCE. 



1956. Surface water temperatures at tide 

 stations. Pacific Coast: North and South 

 America and Pacific Ocean Islands. 

 Coast and Geodetic Survey, Special 

 Publication No. 280, 74 p. 



