INTRODUCTION 



The U. S. Navy Electronics Laboratory thermistor chain, 

 deployed from the oceanographic research vessel USS MARYS- 

 VILLE (EPCE(R) 857) (fig. 1A) measures and records vertical 

 sections of sea temperature structure from the surface to a depth 

 of 800 feet. The first thermistor chain cruise by USS MARYS- 

 VILLE was made in June 1961, and the results derived from it 

 and six succeeding, data- collecting voyages have been pub- 

 lished. 1 ' 2 - 3 - 4 - 5 The eighth chain cruise, which covered the 

 coastal waters from San Diego, California, to Mazatlan, Mexico, 

 investigated the nature of vertical and horizontal variations in sea 

 temperature structure off southern Baja California and across the 

 entrance to the Gulf of California. 



To detect the area of a possible water-mass boundary, the 

 thermistor chain was towed in a complex, fan-like pattern ex- 

 tending south of Baja California. This region, probably the most 

 favorable in the northeast Pacific Ocean for acquiring data on 

 thermocline roughness, is characterized by three types of water 

 impinging on each other: (1) the California coastal current, rel- 

 atively cold and of low salinity; (2) the warm, high- salinity, trop- 

 ical, east Pacific water; and (3) the warm, high-salinity Baja 

 California coastal water that wedges into the California current 

 near Cape San Lucas. 6 Each water mass has its own definitive 

 thermal structure as well as modifications resulting from differ- 

 ential advection and large-scale turbulence. 



The data gathered by the thermistor chain were examined 

 for oceanographic processes and types of thermoclines. Two se- 

 lected isotherms, used to investigate depth change or slope, were 

 subjected to autocorrelation of successive depth measurements, 

 and the power spectrum of isotherm depth was determined. 



