Figure 1.— Map of (i) track of STOR cruise TO-60-1 (May 1960), showing hydrocasts, including 10-m. bottle casts, (—•—), 

 and between-station BT's ( — o— ); (ii) part of thetrack of CalCOFI cruise 6004-B (April 1960), showing full hydrocast 

 stations (-.o— ); (ill) areas in which fronts were studied, including front 5, cruise TO-61-1 (April 1961). 



Currents 



At front 5, all parachute drogues were re- 

 leased in the middle of the front or slightly 

 towards, but not in, the warm side. 



At fronts 1, 2, and 5, geomagnetic elec- 

 trokinetograph (GEK) measurements were 

 made using a standard towing pattern (Von 

 Arx, 1950). 



Oxygen 



The oxygen content of water samples taken 

 on hydrocasts was determined on board by the 

 Winkler method (Thompson and Robinson, 

 1939). 



Inorganic Radicals 



Phosphate, nitrate, nitrite, and silicate con- 

 centrations were determined by methods given 

 by Strickland and Parsons (I960). Phosphate 

 and, in consequence, silicate, determinations 

 for TO-61-1 unfortunately were found faulty 



and were rejected. Only phosphate concentra- 

 tion was measured on cruise TO-60-1. 



Chlorophyll a 



The concentration of chlorophyll a in sea 

 water (mostly as phytoplankton) was measured 

 by the method of Ric^.ards and Thompson (1952). 



Productivity 



Productivity at the surface was measured by 

 the C^* method of Steemann- Nielsen (1952). 

 Samples was incubated in a deck incubator 

 (Blackburn, Griffiths, Holmes, and Thomas, 

 1962, p. 8) for half a solar day. Time did not 

 permit the collection and preparation of 

 samples from different depths at different 

 positions in the frontal system, sufficiently 

 close to local apparent noon on the same day. 



Water Transparency 



Measurements of the coefficient of extinction 

 of a beam transmission, a, were made at 



