FISHERY BULLETIN: VOL. 69, NO. 2 



Current. The sea-surface isotherms, corre- 

 spondingly, bend north and south, effecting a 

 much-reduced temperature gradient parallel to 

 the coast. 



BEHAVIOR OF SEA-SURFACE 

 TEMPERATURE ANOMALIES 



To facilitate description, I shall designate as 

 "warm" or "cold" cells, areas where the mag- 

 nitude of departure from noi-mal was 1° C or 

 greater. The evolution of an anomaly can be 

 readily followed by noting the configuration of 

 its principal cell, or cells, in successive months. 

 This is evident in the figures used to illustrate 

 selected examples (Figures 2-30). These show 



of the positive departures from normal within 

 this cell exceeded 3° C. Off the North American 

 coast, the temperature anomalies were negative, 

 with magnitudes greater than 1° C in a broad 

 zone from Alaska to the tip of Baja California. 

 Figui'es 3-5 show subsequent positions of the 

 warm cell in March, July, and October, respec- 

 tively. The maximum intensities waxed and 

 waned over this time period, dropping in March, 

 increasing again to more than 3° C in July and 

 diminishing once more in October. Except for 

 a slight northward shift, the warm cell remained 

 essentially stationary. During most of the peri- 

 od, negative anomalies prevailed in the coastal 



Figure 2. — Sea-surface temperature anomaly for Jan- 

 uary 1949. Hatched areas colder than normal. Heavy 

 lines represent the 1° C anomaly contours which define 

 warm (-f) or cold ( — ) cells. 



Figure 3. — Sea-surface temperature anomaly for March 

 1949. Hatched areas colder than noi-mal. Heavy lines 

 represent the 1° C anomaly contours which define warm 

 (-I-) or cold ( — ) cells. 



the sizes and locations of the principal cells, 

 enclosed by heavy lines representing a magni- 

 tude of 1° C, in the regions relevant to the dis- 

 cussion. The cells are marked by plus or minus 

 symbols according to the sign of the anomalies. 

 The thin lines rei)resent the zero anomaly con- 

 tour separating areas of below normal temper- 

 ature (hatched areas) from those where the 

 temperature was above normal. 



A good example of persistence was the warm 

 anomaly present in the eastern North Pacific 

 throughout mo.st of 1919. In January the warm 

 cell (defined by the 1° C anomaly contour) cov- 

 ered most of the area from lat 30° N to 45° N 

 and long 145° W to 180° W. Maximum intensity 



Figure 4. — Sea-surface temperature anomaly for July 

 1949. Hatched areas colder than normal. Heavy lines 

 represent the 1° C anomaly contours which define warm 

 (-I-) or cold ( — ) cells. 



346 



