QUINN ET AL : SOUTHERN OSCILLATION, EL NINO. AND INDONESIAN DROUGHTS 



equatorial Pacific and the oceanic region off 

 northwestern South America. In general, years 

 when the index is low and El Nino type activity 

 occurs are also years of drought in Indonesia (par- 

 ticularly during the east monsoon season, May- 

 October). 



Using sea salt production on the Island of Mad- 

 ura (near Java), which is a very sensitive indicator 

 of drought and precipitation, as well as some ad- 

 ministration reports from Java estates, compiled 

 by Van Bemmelen ( 1916), Berlage ( 1957) drew up 

 a complete series of east monsoons drier than 

 normal, from 1830 to 1953. Although 937( of the 

 drought periods occurred during years when El 

 Niiio type events were under way (Table 7), only 

 77*^ of the periods when El Nino type events were 

 underway were also designated as periods of east 

 monsoon drought (Table 8). Nevertheless, the as- 

 sociation between occurrences of these two 

 FIGURE 7. -Frequency distributions of rise time from trough to phenomena and changes in the Southern Oscilla- 



pealt and fall time from peak to trough lin months) for the triple i- • j i. j i u- -iu *- 



^ . , r o .u /-> 11 ^-  J tion mdex trends are close enough in either case to 



6-mo running mean plots of Southern Osculation index " 



anomalies (see text). The number of cases falling within a class indicate common relationships With the large- 



interval is entered at the top of the relevant histogram element, scale ocean-atmosphere changes over the Indo- 



Table 6.— Time (in months) between index peak and El Nino type event onset (assuming onset is in March 

 of indicated year), and time between index peak and associated Indonesian drought onset (assuming onset 

 is in May of associated year). Pressure indices (see text) used to determine time of preevent peak were: S-B, 

 Santiago-Bombay; S-D, Santiago-Darwin; JF-D, Juan Fernandez- Darwin; E-D, Easter-Darwin; T-D, 

 Totegegie-Darwin; and R-D, Rapa-Dai-win. In last column ND indicates no associated drought. 



675 



