ABNORMAL SUMMERS IN THE PERUVIAN COASTAL CURRENT 803 



given to the guano-birds, consists since the first years of its existence 

 in haAing initiated and supported scientific investigations related not 

 only to the birds, but also to the whole ecological and hydrological 

 complex in which they live and upon which depends their well-being. 

 Selected from the representation of abnormal situations are the 

 years 1939, 1941 and 1953. Maps concerning the year 1947 which might 

 be looked at as an abnormal year have been inserted. It has been in- 

 cluded only because it shows for the month of March an ample review 

 of the conditions in the outer limits of the Gulf of Guayaquil. All 

 available data have been sampled and averaged in squares of half a 

 degree of geographical latitude and half a degree of geographical longi- 

 tude, and according to the averages thus obtained isotherms were 

 traced. For all the above mentioned years drafted charts are presented 

 for the months of March and April, although in some cases maps refer- 

 ring to February would already show some major anomalies; these, how- 

 ever, have been left out, in order to avoid undue length of this paper. 

 The number of observations on which these maps are based is as 

 follows: 



1939 March 131 April 157 

 1941 " 619 " 293 



1947 " 855 " 681 



1953 " 380 " 737 



An isothermic chart for normal conditions in the Peruvian Coastal 

 Current (Fig. 1) shows the isotherms running parallel with the conti- 

 nental coast, whilst abnormal situations originated by an invasion of 

 the Equatorial Countercurrent in 1891 and 1925 are represented by the 

 almost perpendicular course of the isotherms to the shoreline (Figs. 2 

 and 3). On the other hand, both of these maps show along the whole 

 Peruvian littoral as far south as Callao (Fig. 2) or a little further than 

 10° S, temperatures of 26° C, although perhaps in the immediate vici- 

 nity of the coast, lower temperatures may have been present. 



None of our charts (Figs. 4-7) shows something similar, running 

 all the isotherms more or less parallel to the coast. The highest inshore 

 temperatures have been observed in 1941, but the highest temperatures 

 in the outer part of the Gulf of Guayaquil and also off the southern- 

 most part of Peru were observed in 1953. March 1939 (Fig. 4) shows 

 the nearest approach of a 27° isotherm to the Peruvian coast at 8°S 

 and that of the 26° isotherm at 10° S. The extension of the hydro- 

 graphic perturbance brought forth by the warm waters which evidently 

 came from the north is easily seen by comparing the maps for March 

 1939, 1941 and 1953 (Figs. 4, 5 and 7), with March 1947 (Fig. 6), where 



