Isaacs 



The remainder of this discussion will outline the plans at 

 Scripps Institution for a study of these large-scale anomalies in the 

 North Pacific. 



One of the principal defects in our information about these 

 events is the paucity of our knowledge of what is transpiring beneath 

 the sea surface and how deeply the anomalous temperatures are dis- 

 tributed. We do not know whether these anomalous regions result from 

 an unusual transport of water or from some change in cloud cover, 

 evaporation, mixing, heat exchange or other alteration in thermal 

 flux. 



Some insight on the probable conditions has emerged from 

 a pilot study that we have carried out. This study has brought to 

 light a number of curious features of these changes, all of which 

 guide us in designing a study of their nature. I will show only a 

 few examples of these results, which, none-the-less will demonstrate 

 the strong indications that they provide. 



Figure 6 presents data for a number of North Pacific 

 stations and shows the log ratio of the monthly temperature change 

 (temporal gradient) at the station and the long-term average monthly 

 temperature change for that station, plotted against the sea surface 

 anomaly for that station. One might properly expect that the 

 temperature change at a station at the time of an intense anomaly 

 might depart greatly from the normal, and that it might be near 

 normal during normal conditions. Figure 6 argues that this is by no 

 means the case, and, if there is any trend, the regions of intense 

 anomaly follow the normal seasonal temperature cycles more closely 

 than do the normal regions'. 



Similar results emerge from the analogous relationship of 

 the monthly horizontal temperature gradient and anomalies. 



These findings argue that these large-scale anomalies 

 result from similarly large-scale homogenous effects, with variations 

 in the effects occurring principally at the edges. The results also 

 allow the possibility that the "normal" conditions are unstable and 

 that two relatively stable conditions exist, one in which tempera- 

 tures are above normal and one with temperatures below normal. 



Figure 7 is a plot of the relationship between the anomaly 

 at a station for a given month and the anomaly of the monthly 

 temperature change preceding the month. At first thought this 

 appears to be a naive approach, and as would be expected, most warm 

 anomalies are preceded by anomalous heating and most cold anomalies 

 are preceded by anomalous cooling. Beyond this point, however, is a 

 strangeness to the relationship. Warm anomalies often survive 

 anomalous cooling, but cold anomalies very seldom survive anomalous 

 heating. This is shown by the abundance of point in the fourth 

 quadrant of the graph and the paucity of occasions in the second 



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