Survey #10, 10- 1 3 April 1959. Fi gures 45-47. 



The usual upwelling pattern is evident at this time. There were f lows - 

 of cool upwelled water out of the Bay of Panama and the Bay of San Miguel. 

 The southward flow of surface waters is noted to include only those waters 

 above 10 m. The isotherm patterns at 50 and 75 m indicate an inflow of cool 

 water along the trough in the west side of the Gulf. 



SUMMARY 



Upwelling is evident from the temperature distributions during surveys 

 made in March 1955, April 1956, March 1957 and 1958, and April 1959, The iso- 

 therm patterns indicate a southward flow of upwelled water at the surface out 

 of the Bay of Panama and perhaps also out of San Miguel Bay in the eastern 

 side of the Qulf. Cool water apparently enters the Gulf along and above a 

 trough in the western side, about half-way between the western coast of Panama 

 and the Archipelago de Las Per las. This inflow is present during times of 

 upwelling as well ais during times when warm water is present throughout the 

 area. In a few instances, the pattern of isotherms indicates a general 

 counterclockwise circulation at and near the surface. 



The figures indicate that water is upwelled from depths of at least 50 m, 

 which is in general agreement with published estimates of 35-75 m. 



The data also are consistent with published interpretations for the 

 period surveyed regarding the general conditions in the Eastern Tropical 

 Pacific. These, briefly, are that 1955 was colder than usual; 1956 was 

 cool, but near the long-term means of temperature and other hydrographic 

 conditions; 1957 and 1958 were unusually warm (the warmest surface waters 

 were recorded in July 1957) ; and 1959 showed a return from the warm 

 situation to one more near the long-term mean. 



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