S7ERDRIIP ET AL. : "E. W. SCRIPPS" CRUISES, 1938 



15 



time a current in the opposite direction. The 

 Counter Current was well developed, but from our 

 observations it is not possible to decide whether 

 this flow extended northward all along the coast 

 or whether it turned southward again to form an 

 anticyclonic eddy. 



The surface topography for Cruise V, October 

 26 to November 5 (chart 5), is based upon an in- 

 complete series of observations, since the third 

 section was not finished. The general flow to- 

 ward the south and east offshore was again modi- 

 fied by the inflow of water from the west. Al- 

 though this water was ultimately carried away to 

 the southeast, there is some indication of a 

 northerly branch. Near shore there are several 

 eddies which indicate a flow toward the north- 

 west, but the flow has not the character of the 

 fully developed Counter Current shown in the 

 other charts. 



The surface topography for Cruise VI, Decem- 

 ber 9 to 18 (chart 6), bears a striking resem- 

 blance to the data obtained on Cruise I, which 

 indicates that there may be a rather clearly de- 

 fined pattern in the annual cycle. Once again 

 there was a general southeasterly flow offshore 

 separated from the Counter Current by a trough 

 line. The Counter Current extended northward be- 

 yond Point Conception as a well-defined flow. 

 There was inflow from the west in the southwest- 

 ern part similar to that encountered on most of 

 the cruises. 



From the results of these six cruises the 

 variations in the surface circulation during 1938 

 may be described as follows: The pattern of flow 

 is dominated by two currents flowing in opposite 

 directions, namely, the California Current toward 

 the southeast and the Counter Current toward the 

 northwest. The nature of the circulation in the 

 area covered by these investigations depends upon 

 the relative development of these two currents. 

 The presence of eddies of different sizes and 

 probably of little permanency adds to the com- 

 plexity of the pattern of flow as found on each 

 cruise. During the winter months (charts 1 and 6) 

 the Counter Current has its maximum development 

 with the northward flow extending alongshore as 

 far north as observations were made. During the 

 winter months the part of the California Current 

 represented by the southeasterly flow offshore is 

 poorly developed, except in the southern part of 

 the area where it is augmented by an inflow from 

 the west. This inflow is greatest during the 

 winter months. V/ith the greater development of 

 the northwest winds during the spring months the 

 California Current increases in extent and veloci- 

 ty. As a result, the Counter Current is reduced 

 or disappears entirely (chart 2). Following the 

 period of maximum development of the California 

 Current during the spring, there is a progressive 

 breakdown of the southeasterly flow and a re- 

 establishment of the Counter Current. The pres- 

 ence of numerous eddies in the offshore area in- 

 dicates that the flow must be extremely unstable. 



The Counter Current has its greatest development 

 during the winter months when it extends north- 

 ward beyond Point Conception. Frequently a part 

 of the Counter Current turns inshore and the flow 

 is again to the south near the coast of southern 

 California, as shown in charts 3 and 6. 



The California Current and the Counter Current 

 are separated by a trough line which extends south- 

 eastward from the vicinity of Point Conception. 

 During the winter this runs some distance to the 

 west of Point Conception but with the onset of the 

 northwest winds in the spring it moves in toward 

 the coast. During the spring and summer this 

 trough line represents a divergence and is the 

 zone of active upwelling, particularly near the 

 coast. ^ 



Currents at 200 meters . - For each of the six 

 cruises the detailed topography of the 200-deci- 

 bar surface relative to the 500-decibar surface 

 is shown in charts 7 to 12. Even at this depth 

 the pattern of flow is complicated and subject to 

 variation. The southeasterly offshore current 

 is not clearly defined or may be entirely absent, 

 but there is always some transport to the north 

 near shore. It is this northerly flow, termed 

 the Coastal Deep Current,* which brings in south- 

 ern water of a higher salinity and a lower oxygen 

 content than those of the water found in the off- 

 shore area. The trough line has been shown to be 

 a zone of active mixing. There is some similarity 

 between the flow at the surface and at 200 deci- 

 bars, but even on Cruise II, when there was no in- 

 dication of the Counter Current at the surface, 

 there was a northerly flow at this lower level. 

 No annual cycle could be detected in the currents 

 at this level. 



Temperature and salinity distribution at the 

 surface. - The distribution of temperature and 

 salinity at the surface for each of the six 

 cruises is shown in charts 13 to 18. The tempera- 

 ture distribution is always characterized by a 

 tongue of relatively cold water extending south 

 and east from the coastal area to the north of 

 Point Conception. The extent and location of this 

 tongue varies during the course of the year and in 

 general corresponds to the trough separating the 

 flow to the south from the Counter Current sys- 

 tem. On all cruises the lowest temperatures were 

 found near Point Conception and the highest tem- 

 peratures in the offshore water and in the Counter 

 Current off San Diego. The maximum and minimum 

 temperatures encountered on each cruise and the 

 stations at which they occurred are given in 

 table 2. The location of the stations may be ob- 

 tained by referring to figure 1 in the introduc- 

 tion to this report. During the spring and sum- 

 mer months the highest temperatures occurred off 

 San Diego, but during the remainder of the year 

 they were found in the southwestern part of the 

 offshore area. 



*rbid. 



