PRELIMINARY DISCUSSIONS 



RESULTS IN PHYSICAL OCEANOGRAPHY 



By 



RICHARD H. FLEMING 



Tables A and B, contained elsewhere in this 

 report, give interpolated values based on the 

 physical and chemical observations obtained by 

 the "E. U. Scripps'' on siz cruises off the coast 

 of southern California in 1938. Charts show for 

 each cruise the topography of the 0- and 200- 

 decibar surfaces relative to the 500-decibar 

 surface and the distribution of temperature and 

 salinity at the surface and at depths of 50 and 

 200 meters. Additional charts show the dis- 

 solved-osygen content at 200 meters and, for 

 Cruises I, II, and III, the phosphate-phosphorus 

 distribution at 50 meters. These charts will be 

 briefly discussed, but a detailed examination of 

 the observations will be postponed. Since the 

 chief purpose of this investigation was to de- 

 termine the nature of the annual cycle, the 

 charts for the six cruises dealing with the same 

 observations will be discussed together. 



Surface currents . - The dynamic height anoma- 

 lies of the surface relative to the 500-decibar 

 surface are shown for the six cruises in charts 

 1 to 6. The contours have been drawn for inter- 

 vals of one dynamic centimeter and the arrows in- 

 dicate the direction of flow. The inset diagrams 

 show the theoretical relation of the distance be- 

 tween the contours to the velocity. 



The results of the "Bluefin" investigations 

 in the spring and early summer of ISS?-*^ showed 

 that the current in the offshore area was di- 

 rected to the southeast. This current had a 

 tendency to flow in the direction of the coast- 

 line to the north of Point Conception and then to 

 deviate from the coast to the south of this 

 point. Inside of the flow to the southeast, 

 v;hich can be considered as part of the California 

 Current, was found a flow in the opposite direc- 

 tion which was called the Southern California 

 Counter Current. In March, May, and June, 193V, 

 this Counter Current reached only as far north 

 as the Channel Islands. There, or to the south- 

 east of the Channel Islands, the Counter Current 

 turned around and followed the coast as an in- 

 shore current to the southeast. The Counter Cur- 

 rent may be considered as part of two eddies, one 

 cyclonic eddy which was usually centered near 

 San Nicolas Island, and one anticyclonic eddy 

 with its center near San Clemente Island. 



Examination of charts 1 to 6 will show that 

 in 1938 the currents had the same general charac- 



^H. U. Sverdrup and R. H. Fleming, "The Waters 

 off the Coast of Southern California, March to 

 July, 1937," Bull. Soripps Inst . Oceanog. (1941), 

 vol. 4, no. 10, pp. 261-378. 



ter as in 1937, but in several instances the 

 Counter Current continued north past Point Con- 

 ception and usually the pattern of flow was com- 

 plicated by the presence of eddies of different 

 sizes, particularly in the offshore area. 



During Cruise I, February 15 to 25 (chart 1) , 

 the California Current was broken up by a series 

 of large eddies. The topography indicates a gen- 

 eral transport toward the southeast and an appre- 

 ciable influx of water from offshore in the south- 

 western part of the area. A well-developed trough 

 separated the offshore flow and the Counter Cur- 

 rent, which at this time extended northward be- 

 yond Point Conception as a clearly defined cur- 

 rent. The anticyclonic eddy southeast of San 

 Clemente Island was also fairly conspicuous. 



In comparison with the other charts, that for 

 Cruise II, April 8 to 12 (chart 2), appears ex- 

 tremely simple, but this may be because of the 

 fact that the representation is based on observa- 

 tions from only the northern and southern lines. 

 However, the observations show no indication of 

 the Counter Current, which on Cruise I was clear- 

 ly demonstrated by the data from these two lines. 

 There was a general flow toward the southeast 

 covering the v\rhole area, with some inflow from 

 the west in the southwestern part. 



The surface topography for Cruise III, June 7 

 to 16 (chart 3), shows that the California Cur- 

 rent had increased in velocity and that the Count- 

 er Current was again present, but only in the 

 southeastern part of the area. A trough extended 

 southward from Point Conception but there was no 

 indication of a flovf to the north past Point Con- 

 ception. The band of high velocities in the 

 California Current is comparable to similar bands 

 found on the second and third "Bluefin" cruises 

 in May and June, 1937^ and can, like these, 

 probably be ascribed to the effect of transport 

 of light surface water away from the coast by the 

 prevailing northwesterly winds. The band of high 

 velocity occurred along the boundary separating 

 the warm and light offshore water from the colder 

 and heavier upwelled water. 



The surface topography for Cruise IV, August 

 16 to 26 (chart 4), shows an extremely irregular 

 pattern of flow in the offshore area. There was 

 no net transport of water to the southeast and 

 the high velocities appear to be associated with 

 large eddies. It is also interesting to note 

 that instet^d of inflow from the west in the 

 southwestern part of the area, there was at this 



2ibid. 



[13] 



