TESTING FOR CHANGE IN THE FREQUENCY OF EL-NINO EVENTS

This note describes and applies a test for trend in the frequency of E l Nino events over the period 1525-1987. Although there appears to hav e been a significant increase in frequency over this period, this resu lt is consistent with an overall increase in the completeness of the h istorical record. When the analysis is repeated for the later part of the period and for strong events alone, no significant trends are foun d.