EBER: SEA-SURFACE TEMPERATURE ANOMALIES 



Figure 28. — Sea-surface temperature anomaly for Jan- 

 uary 1962. Hatched areas colder than normal. Heavy 

 lines represent the 1° C anomaly contours which define 

 warm ( + ) or cold ( — ) cells. 



P'iGi'RE 29. — Sea-surface temperature anomaly for June 

 1962. Hatched areas colder than normal. Heavy lines 

 represent the 1° C anomaly contours which define warm 

 ( + ) or cold ( — ) cells. 



relative to the width of the current can create 

 an anomaly of 1° C to 2° C. The ampHtude of 

 the perturbation in the current must, of course, 

 be greater than that in the temperature field, 

 since the water must adjust toward new equili- 

 brium temperature appropriate to the local heat 

 exchange processes as it changes latitude. Thus, 

 a parcel of water following a northward de- 

 flection of the streamlines would arrive at the 

 northern bend, or crest, of a standing wave with 

 a temperature lower than it would have had if 

 no deviation from zonal flow had occurred. Ow- 

 ing to the advective eff'ect, it would nonetheless 

 be warmer than an equivalent parcel of water 



120* ISO* WO* iXr 160* ITO* wo- ITO- WO* 00* 140* 130* 120* IW* 100* 90* BO* 



Figure 30. — Sea-surface temperature anomaly for Sep- 

 tember 1962. Hatched areas colder than normal. Heavy 

 lines represent the 1° C anomaly contours which define 

 warm ( -|- ) or cold ( — ) cells. 



reaching the same location by a normal, zonal 

 trajectory. 



The existence of a perturbation upstream 

 from the location where the West Wind Drift 

 splits may have a significant effect on the pro- 

 portional flow into the Alaska Gyre and the Cal- 

 ifornia Current. For example, in a wave 

 formed by a northward deflection of the zonal 

 current, water moving downstream from the 

 crest would have a southward component which 

 might favor more transport into the California 

 Current. A strengthening of this current would 

 cause the isotherms to adjust to the effects of in- 

 creased cold advection and local heat exchange 

 processes southward of their normal positions, 

 creating a negative anomaly. Correspondingly, 

 the reduced northward transjiort would decrease 

 warm advection into the Gulf of Alaska and 

 the isotherms would adjust to equilibrium po- 

 sitions farther south than normal, also creating 

 a cold anomaly. 



If the northward deflection in the foregoing 

 example is replaced by a southward deflection, 

 then, after passing the southern bend or trough 

 of the wave, the water would approach the 

 coast with a northward component, favoring 

 more transport into the Gulf of Alaska. The 

 balance between advection and local heat ex- 

 change would be established with the isotherms 

 north of their normal positions, creating a warm 

 anomalv. 



353 



