Paper 2 



ATMOSPHERIC CLIMATOLOGY A Im D ITS EFFECT 

 ON SEA SURFACE TEMPERATURE - 1976 



Robert R. Dickson and Jerome Mamias 



The year 1976 saw the continuation of the abnormally strong 

 westerly flow which has tended to characterize the circulation 

 over much of the Northern Hemisphere for the past five years 

 (Namias and Dickson 1976; Dickson and Namias 1978). However/- it 

 is important to note that 1976 also saw the apparent culmination 

 and reversal of this tendency with a progressive amplification of 

 the circulation as the year progressed. We may crudely summarize 

 these changes as follows. A winter of record westerlies at 

 relatively high latitudes over the Atlantic and Pacific sectors 

 was followed by continued westerly vigor in spring accompanied by 

 a return of winds and pressure belts to more normal latitudes. 

 Thereafter/^ amplification of the flow progressed throughout the 

 summer as a dominant blocking ridge built over northwestern 

 Europe with shortening of wavelengths upstream^ and in fall the 

 amplification of the circulation was completed with the 

 e s taPl i shmentx on averager of a full latitude 5-wave system in 

 the upper westerlies. To some extent/ each of these component 

 features of the circulation was reflected in the mean annual 

 distribution of 700 mb height anomaly for 1976 (Fig. 2.1); in 

 this figure^ for example/ the well-developed North Pacific and 

 North Atlantic oscillations are clearly shown/ as are the 

 dominant ridges over the western seaboards of North America ana 

 northwest Europe. However/ in a ye^r when the key development 

 was change itself/ a single "mean annual" distribution such as 

 this provides a less meaningful illustration of events than do 

 the individual maps of circulation anomaly for each season. 

 These are described in detail below. 



Winter 1975-76 displayed many of the circulation characteristics 

 of the preceding season and indeed of the preceding year. As 

 shown in Figuce 2.2/ intense suotropical rid&es dominated both 



M.A.F.F. Fisheries Laboratory/ Lowestoft/ Suffolk/ England. 

 ''Scripps Institution of Oceanography/ La Jolla/ CA 92C37. 



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