ENSO (El Nino Southern Oscillation Index) is computed using the anomalies in SST (Sea Surface Temperature) for a 3-month running mean period. While exploring correlation between ENSO and monthly rainfall for Indian region, should the rainfall series be also formulated as anomalies of 3-month running mean or individual monthly correlations between ENSO and rainfall anomalies should be explored?
Thanks in advance for your useful inputs!